ggggg^j?^^'' LIBRARY OF CONGRESS, 'cJ^ ®|ap.c„— - Snjnjrig|l !f o , Shelf .:M 1.5 - UNITED STATES OF AMERICA. ELEMENTS ^ Scientific and Practical AGRICULTURE. ADAPTED TO THE EEQUIEEMEHTS OF SCHOOLS AND THE AGRICULTUKAL PUBLIC. BY—— 1/^ G-EOK/G-E C3-EnyLDyLELXj IMIcIKI^"^, 2,. ' Late Examiner of Fublic Schools, Allegany County, Md, fl BALTIMORE, MD.: The Baltimore Publishing Company, Peinters, Ko. lOG E. Baltimore Street. 1887. "The fundamental principles of plant-groidh and tillage, if not occupying more tlian an hour a iceeJc in the school, would exert a heneficial and pou-ei-ful educational influence, and add untold riches to the tvealth of our people.''^ — Dr. F. M. IIexameu. "But it is not the mere practiced utility of these agricidtural truths which is of importance; their influence upon mental cul- ture is most heneficicd, and the new vieivs acquired by the knowledge of them enable the mind to recognize in the phenomena of nature pn'oofs of an infinite wisdom, for the unfathomable 'profundity of ivhich, language has no expression.'^ ^-BaRON LlEBIGi PREFACE. In the following treatise it has been the aim of the author to render the various investigations as simple, natural, and easily- understood as possible, and to establish and illustrate them in a plain and familiar manner, without descending to mere puerility. He trusts the methods by which he establishes the processes causing the first soil on the face of the earth, the formation of the secondary rocks, and succeeding formations, and the modes he has employed in explaining the theory and practice of farm cultivation, as well as the causes of the different kinds of soils, etc., will divest those subjects of much of the taystcry that has long enveloped them. In like manner, using freely what has been done by previous writers, he has endeavored to simplify those elementary prin-- ciples which underlie the Various operations of practical and profitable husbandry. Much absolute novelty, except in the mode of exposition) cannot now be expected in a work on the Elements of Scientific and Practical Agriculture. Some of the matter, however) the author thinks, is entirely new, while others are for the first time systematically arranged, clearly developed, and fully explained in familiar language. With regard to the useful application of the science of agri- culture to practical farming, there is no difference of opinion among men of sound judgment, and it is only with that subject this elementary work has any concern. The use of technical terras has been avoided as much as possible. The derivation and meaning of a few words, whicli may not be familiar to all, liave been given at the end of the vi PREFACEl. book for the convenience of those who may not have a dictionary at hand. Questions have also been added, which arc merely suggestive, Wlien the work is used for a text-book, the teacher should bo particular to bring out the salient points of each subject, and encourage the pupil to amplify and illustrate his statements in his own words, bearing in mind that the most interesting subject becomes dry and irksome if not thoroughly understood. It may be assumed as self-evident that agricultural instruc- tion, to be a national benefit, must be accessible to the people, especially the cultivators of the soil. It may also be assumed that this end can be best attained through the public schools, by )neans of a suitable text-book. With this end in View, this work is given to the public. How successful the author has been in supplying the need, the people must judge. The desire of the author has been to supply a useful, reliable, and compi-ehensive book at as moderate a price aS possible; and he believes lie has given in this work a very large amount of matter in proportion to its size. Cumberland, Md., February, 1887. CONTENTS FIBST DIVISION. CHAPTER. PAGE. T. The Chief Object of Agriculture, ... 11 IT. The Growth of Plants, 13 III. The Germination of Seeds, .... 15 IV. How Plants Take Their Food, ... 17 V. Substances Found in Plants, .... 18 SECOND DIVISION. VT. The Organic Coznpounds, .... 19 VII. The Inorganic Substances, 20 VIII. Plant Food, 22 IX. How Plants can be Grown Without Soil, . . 24 X. How Plants Feed, ...... 27 XL The Soil and Its Characters, .... 28 XII. Geological Influences on National Character, . 31 XIII. The History of the Soil, 33 XIV. Analyses of Primitive Rocks, .... 35 XV. Agencies Wliicli Reduce Rock to Soil, . . 30 XVI. The Pulverizing of Rock in Which There is No Iron, ....... 38 XVII. Reduction of Rock to Soil Condition, . . 40 XVIII. Physical Composition of the Soil, ... 43 THIRD DIVISION. XIX. Capillary Attraction, 45 XX. Physical Condition of Soils 47 Yin COI^TEOTS. FOURTH DIVISION. CHAPTER. XXI. Chemical Analyses of Soils, . XXII. Agricultural Chemistry, .... XXIII. The Beneficial Effects of Drainage, XXIV. The Beneficial Effects of Drainage, . XXV. Objections to Drainage, .... XXVI. Organic Constituents, .... XXVII. How to Remedy Some Bad Characters of Soils XXVIII. Analyses of Different Kinds of Soils, XXIX. The Great Value of the Double Silicates, . 3iXX., The Beneficial Effects of Tillage, . XXXI.' The ^York of the Plow, .... XXXII. Lime Pans, and Other Field Pans, XXXIII. Agricultural Implements, .... XXXIV. Preparations for Seeding, PAGE. 48 49 52 53 58 G2 G4 G6 G8 70 73 74 7G 77 FIFTH DIVISION. XXXV. Elements of the Soil, XXXVI. The Organic Elements, XXXVII. The Metallic Elements, XXXVIII. Binary Compounds, XXXIX. The Atmosphere, . 79 81 82 83 85 SIXTH DIVISION. XL. Tlie Dissolution of Plants and Animals, . 87 XLI. . The Exhaustion of the Soil, ... 89 XLII. Substances Used by Vegetables, ... 91 XLIII. Tlie Quantity of Substances Used l)y Differeut Plants, 93 XLIV. Remedies for Exhaustion, .... 94 XLV. Fallow Crops, 97 XLVI. Rotation of Crops, 98 CONTENTS. IX SEVENTH DIVISION. CHAPTER. XLVII. The Great Remedy for Exhaustion, XLVIII. Farm-yard Manure, . XLIX. How to Increase the Fertilizing Manure, . . • • • L. Experiments With Farm-yard Manure LI. Compost Heaps, , . . • LII. Uses of Calcareous Manures, . LIII. Summary of the Virtues of Lime, LIV. Artificial Manures— Guano, Bone, LV. Phosphatic Manures, . . . • LVI. Nitrogenous Manures, . PAGE. . 100 103 Power of 104 107 108 110 112 114 116 118 EIGHTH DIVISION. LVII. Agricultural Plants, LVIII. The Germination of Seeds— Wheat, . LIX. The Germination of Seeds— Pea, Turnip, LX. The Uses of the Roots of Plants, &c., LXI. The Uses of the Stems and Leaves, LXII. The Duties of the Flower in Plant Economy, LXIII. Wheat, Pea, and Clover Flowers, . LXIV. The Attractiveness of Flowers, . 121 122 125 126 128 130 132 133 NINTH DIVISION. LXV. The Utilization of Agricultural Plants, LXVI. Botanical Order of Agricultural Plants, LXVII. Wheat and Corn Crops, .... LXVIII. Barley, Oat, and Rye Crops, LXIX. The Hay Crop, LXX. Clover Hay— Sheltering of Young Plants, 135 137 140 141 144 146 CONTENTS. TENTH DIVISION. CHAPTER. LXXI. Implements for Harvesting Crops, LXXII.' The Reaping and Binding Macliino, LXXIII. Points of Economy of a Machine, . 1>A0E. . 148 151 . 153 f:LEyENTIl DIVISION. LXXIV. Pests of the Farm, 154 LXXV. Insect Pests, 156 LXXVI. Miscellancious Information, .... 159 Questions— First, Second, and Third Divisions, . . 165-6 Third, Fourth, and Fiftli Divisions, . 166-7 Fifth, Sixth, Seventh, and Eighth Divisions, 167-9 Eighth, Ninth, Tenth, and Eleventh Divisions, 169-70 " Eleventli Division, 170 Vocabulary, 173-9 ELEI^EISTTS SCIENTIFIC AND PRACTICAL AGRICDLTDRE. CHAPTER I. CHIEF OBJECT OF AGRICULTURAL SCIENCE. The various operations employed in cultivating the land, so as to make it yield vegetable food abun- dantly, is called Agriculture. The great object of agriculture is to produce from a given space the greatest quantity of certain kinds of vegetation, with a due regard to the quality of the produce, at the lowest cost, without exhausting the soil. The sciences of Chemistry, Botany, and Geology are of great value and importance to the cultivator of the soil, as they furnish the means of knowing the different classes of agricultural plants, how they feed, the quantities of the different substances each kind of plant requires, from Avhence they obtain their food, from whence the soil came in which they grow, and how the farmer can best aid the plant in getting an ample supply of food. We propose to call to our aid only so much of these sciences as may be deemed necessary for the correct understanding of the growth of plants, the tillage of the soil, and the reasons for the practice of intelligent farmers. . . , 12 ELEMENTS OF Metaphysics and the fine arts were carefully stiidied by the Greeks and Eomans, in -which they reached a high standard of perfection; but the natural sciences, the offspring of the inductive system, Avere ignored by them. Until 1820 (Sir Humphrey 'i\i\\) and 1840 (Baron Liebig) agriculture had no scientific basis; it was a mere experimental art. Eflecls were ascertained, but causes were unknown. Happily, chemical analysis and philosophic sagacity at last shed light on the sub- ject. To science we owe most of the comforts of life — ■ such as health, clothing, literature, and locomotion. There is no good reason why the production of our greatest necessity — food — should be excluded from its influence. Agricultural labor, beyond any doubt, develops man's physique; but it has also been said that it develops the muscles at the expense of the brain. Under the scientific and practical system of farming, no such charge can be maintained; because both brain and muscle are stimulated to activity by the multi- plicity of operations, and the varied intellectual inquiries necessary to bring the cultivation of the soil and the growing of crops to a successful issue. Each is thus accorded fair play, and both attain a well developed proportion. The Bible says: "The sleep of a laboring man is sweet." If the farmer could but realize how greatly blessed he is in this particular, by the character of his labor and surroundings, he would not desire to exchange places wdth the nerve-strained sons of commerce, or the followers of the phantom, Dives — the merchant princes of the cities, or the brokers of Wall street. No one leads a life more in harmony with the divine com- mand given to our first parents than the tiller of. the SCIENTIFIC AND PilACTICAL AGEICULTUKE. 13 soil; and no one can follow a more peaceful, enjoy- able, and healthful pursuit, or has a freer and fuller opportunity for the profitable exercise of intelligence and contemplation of the wonderful goodness of God. CHAPTER II. THE GROWTH OF PLANTS. Plants can only grow when they have a proper supply of the materials they need for building up their various parts; they, like animated beings, require food ; and although in a wild state, they can obtain all the nourishment they require from the air, and from the soil in which they grow; yet, when we produce them in particular places, and in great quantities, for the use of man, we must take great care that they be supplied with food proper for them, and sufficient in quantity. We shall endeavor, in this work, to explain clearly the principles which regulate the supply of food to the plant, and the way by which tlie farmer is able to assist the plant in obtaining it. The prime object of agriculture, then, is to grow and multiply plants ; therefore, it will be necessary for us to inquire, at the outset, what plants are com- posed of, and how they grow. It will be observed that all agricultural plants, such as wheat, clover, beets, potatoes, etc., consist of two principal parts. The root, which is pale colored, growing downward into the soil, and irregularly branched; the stem, or top, which is generally green, grows up into the air, sending out branches in a more regular manner, and produces leaves, flowers, and fruit. Some plants are grown by the farmer for their roots, 14 ELEMENTS OF as turnips; others for their leaves and stems, as cloYer and grass ; and others for their fruit and seeds, as corn, wheat, beans, and peas. The farmer, therefore, talks of root crops, green crops, grain crops, and fruit crops. Some roots are thick, and grow straight downwards, sending off slender branching fibres, as carrots and beets; others are entirely fibrous, as the grasses. The uses of the roots are to take in nourishment, and fix the l)lant in the soil. Roots are sometimes much longer than the stems. The roots of wheat have been traced to a depth of seven feet, and those of corn have been known to extend a distance of fifteen feet from the stem. The ends of the root-fibers are fine and deli- cate, and covered with minute hairs, into and through which the nourishment of the plant enters, and finds its way up into the stem. The stem generally grows upward into the air; but in a few the stem lies on the surface, and in others it runs partly underground. The potato is, in reality, a thickened part of an underground stem, the eyes of which are simply buds. The stem is sometimes hollow, as in wheat, and is always made up of bundles of long cells and vessels, through which water and other substances, taken in from the soil by the roots, pass up into the leaves. The most important organs connected with the life and growth of all plants are their leaves. A leaf is a thin layer of minute cells spread out to the air, strengthened with ribs or veins, made up of stouter cells or vessels, and covered on both sides with a fine membrane, nearly transparent. In these membranes are minute openings, called pores, through which the plant takes in air and gives off water and gases. When a plant is full grown, flowers appear upon its branches. Some plants, as the carrot and turnip, take SCIENTIFIC AKD PEACTICAL AGEICULTUEE. 15 two years to produce their flowers. The first year the root grows thick and fleshy, the tops bearing only leaves. The second year the plant pushes forth a strong stem; it is then said to have "run to seed." The store of nourishment laid up in the fleshy root, during its first year's growth, is consumed in producing the flowering stem, fruit, and seed, after which the root will be found stringy and spongy, and useless for food. All agricultural plants put forth flowers, but some are very small and dull colored. When the out- side of the flower falls off", the middle part grows into fruit, which contains the seed. A grain of wheat is properly a fruit containing one seed; a bean-pod is a fruit containing several seeds. CHAPTER III. SEEDS AND THEIR GEEMINATION. A SEED contains the young plant and sufBcient nourishment, usually consisting of starch or oil, to support the young plant until it is able to support itself. The embryo consists of a plumule, or young bud, from which the stem will grow up into the air; a radicle, or young root, from which the main root will grow down into the soil; and one and sometimes two seed-leaves, which push up above the soil and become the first green leaves of the plant. Three things arc necessary to enable a seed to begin to grow: (1) Moisture, which is absorbed by the seed, causing it to enlarge and burst its hard outside case; (2) Warmth, of which some require much more than others in the first stage of germination; and (3) Air, 16 ELEMENTS OF from Avhich tlie seed derives oxygen and carbonic acid gas. When a seed, therefore, is kept moist and warm in the air, it will begin to grow, no matter whether it be placed in the soil or not; but, as it lias to obtain most of its food from the soil as soon as its own store is exhausted, it is best to sow it in the soil at once, being particular to see that it can obtain enough moisture, warmth, and air. The seed then becomes swollen, the young bud enlarges and bursts through the outer skin, the plumule rises into the air, carrying with it the seed-leaf or leaves, or opening out its young green leaves to the sunlight while the radicle descends into the soil, sending off minute branching fibers. The oxygen of the air acts upon the stored-up food in such a way that the oil and starch are converted into a kind of sugar. That solid substances can be dissolved in water, is difficult for the learner to realize; yet we see instances of it every day in the case of easily dissolved substances, as sugar and salt. A lump of sugar put into a glass of water soon disappears ; still we know it is there, and its presence is easily detected by the taste. Most of the sparkling spring water which we drink has lime, magnesia, iron, and other substances in it; yet it looks clear and bright to the eye. All the sub- stances which constitute the food of plants must be dissolved in water, in this clear and complete manner, before they can be taken up by the root- lets of plants. SCIEifTIFIC AND PEACTICAL AGEICULTUKE. 17 CHAPTER IV. ROOTS OF PLAKTS AND HOW THEY TAKE IN FOOD. If you loosen the earth around and under the root of any young plant, and carefully pull it up, wash off the soil gently in a pan of water, and then examine the root, you will observe it to consist of a number of wMtisll fibers, growing finer and whiter towards the tips. These fibers, put under a strong magnifying glass, will be seen to be hollow tubes, closed at the ends, and having very thin walls. It is through the delicate skin of these hairs on the root-fibers that the plant absorbs the clear water in which its food is dissolved. As the roots grow older and thicker, they lose their hairs, and their outermost layer becomes hard and forms a rind or bark, while the taking in of the water containing the food is carried on by the hairs and cells, upon newer fibers, branching out and spread- ing v.'ider and deeper into the soil. In poor soils root-hairs are found to be more abundant than on fibers growing on good soil, because more eff'ort is required to be put forth by the plant in finding food from the thinly distributed nourishment than in good soil, where all the materials required are at hand in abundant supply. But the young student naturally asks : If no openings exist in these hair-fibers, how can the water get in? The following experiment will remove any doubt that may exist on this point: Take a small glass funnel and tie tightly over the mouth of it a piece cf bladder or very thin India rubber, such as is used for children's 18 ELEMENTS OF balloons; now j)Oiir into it some water, in which sugar or salt is dissolved, and dip the covered end into a basin of clean water. After a time it Avill be found that the liquid in the tube has risen, and, on tasting the water in the basin, some of the sugar or salt will be found to have penetrated the membrane. Thus it is proved that fluids, separated ])y a membrane, are able to pass through and diffuse into one another, though there arc no holes to be found in the dividing membrane, even by the most powerful microscope. CHAPTER V. WHAT PLANTS AKE COMPOSED OF. We shall now examine into the composition of plants, and ascertain what becomes of the water and substances, held in solution, which they have drunk up or absorbed. In a green growing plant the most abun- dant substance is water. Fresh meadow grass contains from seventy-five to eighty-five per cent, of water, while in turnips more than ninety per cent, is found. There- fore, one hundred pounds of fresh grass, when made into hay, will weigh about twenty-five pounds; and, if completely dried in an oven, will weigh only about fifteen pounds. The water contained in the plant is not stationary, but is passing through the plant, from cell to cell, until it reaches the leaves, where, being spread out to tlie air, it is quickly evaporated through the minute openings, which we before explained as abounding in its covering membrane. A healthy medium sized cabbage has been found to evaporate nearly a pint of Avater in twelve hours; and it lias been calculated that an acre of SCIENTIFIC AI^D PRACTICAL AGRICULTURll. dS cabbages -will give out in the course of twelve hours, by evaporation, more than ten tuns of water. The frame-work of the plant, of which the walls of the cells are made, consists of a substance called cellulose, the most familiar form of which we see in paper or hornets' nests. We may consider, then, the plant to be constructed and built up of an infinite number of minute paper boxes, closed on all sides; and the water, with its contents, oozes through the sides of these boxes, from one to another, till it reaches the leaves; and on its way back from the leaves, each retains that portion of the nutriment which it needed and passes the rest on to its neighbors. Another very abundant substance is starch. This is in the form of minute grains, stored up in many of the small boxes or cells, which are often packed full of them. A potato consists almost entirely of cells packed and crowded full of starch granules. Starch can be very easily converted into sugar, and in many plants sugar is very plentiful, as in the sweet fruits, sugar cane, in the cells of the beet-root, and sap of the sugar maple. When barley is made into malt, the warmth and moisture cause the starch to be turned into sugar. CHAPTER VI. THE ORGANIC COMPOUNDS. All the substances mentioned in the former chapter, namely, water, Cellulose, starch, sugar, and oil, are found by chemists to be composed of three ele- ments, or simple substances, viz., carbon, oxygen, and hydrogen. Water is composed of oxygen and hydrogen; cellulose, sugar, starch, and oil are each 20 , JILEMENTS OF composed of carbon, oxygen, and hydrogen, and, in the plant, are often changed from the one to the other. There are two substances in the phint which must be specially mentioned, and which are made up of four elements, viz., carbon, oxygen, hydrogen, and nitrogen. The first of tliese substances is called protoplasm, a kind of jelly-like material found in all living cells, which, under the microscope, is seen to turn round and round in its cell, and is really the life substance in the plant; and the second is called chlorophyll, or leaf-green, which is formed out of protoplasm by the action of sunlight, and is found in all the green parts of the plant. If a plant is kept from the light it turns yellow and then white. You have all witnessed this in the growths made by potatoes in the cellar, and the blanched stalks of celery, which is caused by earthing them up; because, in the absence of liglit, no leaf-green is formed. All the substances of the plant which we have been considering, whether formed of three elements or four, are called organic compounds, because they go to make up the principal part of all organized beings — that is, plants and animals having special mem.bers or organs. CHAPTER VII. THE IXORGANIC SUBSTANCES. If avo take a plant and dry it, and then burn it, all the organic substances disappear and mingle with tlie air, again to be used by otlier plants; and the inorganic, or fixed substances, remain as ashes, which are, in reality, the mineral matters contained in the plant; and these, when analyzed, are found to consist SCIENTIFIC AND PRACTICAL AGRICULTURE. 21 of a number of compounds which are found in many minerals as well as in animals and plants. The following table shows the materials found in plants: ORGAKIC. IKORGANIC. Silica. Potash. Soda. Lime. Phosphoric Acid. Carbonic Acid. Sulphuric Acid. Magnesia. Oxide of Iron. Chlorine. NOX-NITROGENOUS. Carbon, Oxy- gen, Hydro- gen only Starch. Gum. Sugar. Cellulose (or woody fiber' _ Oil. NITROGENOUS. Carbon, Oxy- gen, Hydro- gen, and Ni- Albumen. Fibrine (gluten), trof'en I Casein (legumen). Most of these are the common names of substances with which you are familiar. Potash is so called because it was first obtained by burning plants in a pot, then leaching the ashes and evaporating the water. Iron oxide is the rust seen upon iron when exposed to the air. Silica is the substance which we see in white sand, flint, and quartz-crystals. Ammonia is so called from its having been obtained from the camel-yards near the Temple of Jupiter Ammon, where the worshipers of that idol had congregated for many years; it is also called harts- horn, because of its having been obtained from the horns of the deer. All the inorganic substances named above contain oxygen, except chlorine and ammo- nia. Chlorine, when liberated from its compound, is a yellow, choking gas, but in the plant it is combined with potash or soda; when combined with the latter, it is called chloride of sodium, known to every person Note.— Ammonia Is composed of Nitrogen and Hydrogen, and belongs to tbe organic elements. 22 ELEMENTS OF as common salt. From the strong affinity which clilorinc has for water, if it be set free in a cellar which is damp and mouldy, it Avill destroy the mould and render the cellar sweet and healthful. If an earthen vessel, Avith about two pounds of common salt, be placed in a cellar, and an ounce of sulphuric acid poured over it, the chlorine will be set free from the soda and fill the cellar, Avliich should be tightly shut up for four or five hours. You must be careful not to breathe the gas, and to aerate the cellar thoroughly before entering it. A drink of water is the antidote to the effects caused by inhaling the gas. The acids named in the table, when found in the plant, are combined with minerals, and are what chem- ists call phosphates, sulphates, and carbonates. Silica, also, sometimes forms an alliance with minerals, and these compounds are called silicates. We have, therefore, phosphate of potash, phosphate of lime, a very important compound, which constitutes the chief value of bone as a fertilizer; also, we have the sulphate of potash, sulphate of magnesia (epsom salts), sulphate of lime (gypsum and plaster of paris), corbonate of soda, and carbonate of lime (marble and chalk). CHAPTER VIII. PLANT FOOD. We may now take up the subject of plant food. All these su])stanccs, found in ]ilants that have grown from very small seeds, must have been obtained by them from without; and, to enable them to grow and be thrifty, they must be in reach of these substances. SCIENTIFIC AND PRACTICAL AGRICULTURE. 23 As soon as plants have used up the noul-ishment provided for them in the seed, they require a supply of the following organic materials to build up their soft parts, viz. : Oxygen, hydrogen, carbon, and nitrogen; and the inorganic materials, to build up their frame-work or skeleton, viz.: Potash, soda, magnesia, lime, iron, phosphoric acid, sulphuric acid, silica, and chlorine. Full-sized, healthy plants have been grown to com- plete maturity, without any soil at all, by suspending them, with their roots dipping, into a- vessel of water in which has been dissolved a supply of all these articles of plant food. Some exceedingly interesting experiments have been made in growing plants artificially, with food specially prepared and dissolved in water. Some may be desirous of trying the experiment, and, as it will be instructive as well as interesting, we shall describe in the next chapter one of the best modes of procedure, which has been success- fully tested. It is of great importance to keep in mind the sources from which plants derive their food: First — Air. The air is mainly composed of two gases, nitrogen and oxygen, with a small portion of carbonic acid gas, which is itself a compound of oxygen and carbon, and still smaller quantities of ammonia and nitric acid; the former of which contains nitrogen and hydrogen, and the latter nitrogen and oxygen. Careful experiment has shown that none of the free nitrogen of the air is taken in by plants, and that, small as the carbonic acid is in the air, it is the source of almost all the carbon found in plants. The leaves absorb car- bonic acid from the air, and then, under the influence of sunlight upon the Icaf-grcen, the carbonic acid is separated into its elements (carbon and oxygen); the 2i ELEMENTS OF carbon i^ retained by the i)l;uit, which uses it in forming cellulose, starch, sugar, and otlier substances; Avhile the oxygen is given out to the air. Oxygen is also, at times, absorbed from the air, esi^ecially when the jjlants are growing rapidly and coming into flower. The ammonia and nitric acid are washed down into the soil by the rains, and then taken in by the roots, supplying the plants with a small portion of nitrogen. Second — Water. Pure water is a combination of oxygen and hydrogen. When water is used by the plant, its duty is chiefly to convey other matters, Avhich it holds in solution, to the root; but some of it is divided up and used by the plant in forming the starch and other organic matters. Rain water is the purest natural water known, having nothing dissolved in it but what it has washed down out of the air; but, as soon as it enters the soil, it begins to dissolve the mineral matters there, and carries them to the roots of plants. Third — The soil. We have now seen what plants obtain from air and water; the rest of the nitrogen, and all the mineral or inorganic substances, must be obtained from the soil and brought to the roots clearly and completely dissolved in water. CHAPTER IX. EXPERIMENT WITH WATER CULTURE OF PLANTS. In order to make the experiment of growing a plant to perfect maturity, without being planted in the soil, take a wide-mouthed bottle, capable of holding one or two quarts. It must be fitted with a cork, and a hole 6CIEKTIFI0 AND PRACTICAL AGRICULTURE. 25 made in the centre of the cork, say half an inch in diameter, and an opening cut from it to the circum- ference, 60 tliat the phmt may be glided out and in easily when required. You will next cover the bottle with stout paper, and top or neck with black sealing wax. It is a most important matter that darkness be secured, for plants feed through the roots best in the dark, as well as to prevent any fungoid growth within the dining-room of the plant. We have next to see to the preparation of the bill of fare, and there are many of such bills. We shall select the following one, as suitable for the purpose, which has been successfully used by a celebrated English chemist: Take finely powdered burnt bone (three hundred grains), put in a glass flask with Avater (pint), and to it nitric acid is cautiously added, so as to dissolve the bone, the flask being heated. After this has been done, a solution of carbonate of potash is added to the hot liquor, until it becomes slightly turbid. This represents the only troublesome portion of the cooking arrangements, for it now only needs the three following bodies to be added*. Nitrate of potash, one hundred a-nd seventy grains; crystallized sulphate of magnesia, one hundred and seven grains; and chloride of potas- sium, forty-six grains, with water suflicient to make it up to a quart. We have thus prepared a very large supply of plant food; for although in its concentrated condition it only represents a quart, yet it will really give about ten gallons when properly diluted. When we are going to use the food for..plants, we take about two table- spoonsful, and add it to a quart of distilled water, and mix in with it one drop of a strong solution of perchloride of iron. This weak and delicate liquid 26 ELEMENTS OF now represents a very valuable plant food, and in this condition it is ready for use. The seed having been sprouted in sand, the young plant is washed and then suspended in the hole of the cork, by the aid of cotton, wool, or other similar soft substance, with its roots reaching down to ilio water and its leaf in the air. Until a green leaf appears, clean water is supplied; but on the appearance of the green leaf, the cork and plant are removed from the bottle, the water is poured away, and the bottle filled with the properly diluted food. When the growth of the plant is slow, there need not be any fresh supply of food for fully fourteen days; but in hot weather, when the growth is active, it is necessary to give fresh supplies every seven days. On these occasions the bottle is emptied and an entirely fresh supply of the diluted food is given. In this way you will produce a perfect plant without putting it into the soil. The experiments which have been carried out go far to prove that plants take their supplies in a very dilute form, and yet these homeopathic quantities are really necessary. Take, for example, the one drop of iron solution added to a quart of water, being a ratio of about one to twenty thousand, and yet this minute supply was absolutely necessary. It was discovered by the same chemist that, when this iron was omitted, the young plant became yellow and sickly; but it quickly became green, and assumed a luxuriant growth, when this minute quantity of iron solution was added. In the preparation of these watery solutions it is necessary to use distilled v.ater if we want to arrive at accurate conclusions, because all natural supplies of water hold in solution more or less of the materials which plants require for food. SCIENTIFIC AND PRACTICAL AGRICULTUEE. 27 CHAPTER X. HOW PLANTS FEED. Spring waters are sometimes sufficiently charged with the substances tliey have dissolyed in their passage among rocks an'd soils, so as to be capable of main- taining the growth of plants. Eain-water is also more or less impregnated with matters taken from the air as it falls, so that it cannot be considered perfectly pure. The lesson we may learn from these facts are, that plants take in their mineral food in an exceedingly dilute condition and in a beautifully bright form; likewise we learn that if they do not receive all the materials they require, they soon show that they have some want by presenting a sickly appearance, which will, ere long, result in a cessation of growth, and ulti- mately in untimely death. Some experiments which have been carried out by these trials of water culture have led to the belief that silica is not ahvays necessary to the growth of a plant; but it is safe to conclude, that all these substances found in a plant when grown naturally in a fertile soil, and which are constantly produced there in the highest perfection, are desirable for the plants. It will be always safest for us to accept the constant pres- ence of substances found in the largest and best crops of any cultivated plant, as a sure indication that those substances are desirable for complete growth. It has been proved that many of these substances are absolutely necessary, and, as a matter of prudence, the farmer should regard a complete supply as being needful, and make provision accordingly. 28 ELEMENTS OF In the riglit and jiroper use of these researches, made in the growth of plants by the aid of these solutions of substances found in them, a yaluable lesson is learned, which may be profitably utilized by all cultivators of the soil. The delicate and clean character of the food received by the plants, and the bright and transparent stream of water which conveys the food into the roots, indicate some great changes taking place in the soil; when, for example, farm-yard manure has been used upon the land, the most olTensive materials are often applied, and wisely so, too; but the plant does not feed upon them until, by changes carried on in the soil, they are passed into the circulation in a condition as bright, clean, and odorless as the water which sparkles in the goblets on our dining-tables. CHAPTER XI. THE SOIL AKD ITS CHARACTEKS. Op the three sources of plant food, viz., air, water, and soil, the soil requires from the farmer the most attention, and may be said to be the only one under his control; because air and rain-water can generally be obtained by plants without aid from man, and are the same quality and contain the same properties all over the earth, while soils differ greatly, containing in some places little plant food, and in others the greatest fertility. The cultivation of the soil is now considered by all intelligent men as a manufacturing business of the highest importance to the w^'lfare of nations. Farm experience may justly be recognized as the rudder which controls the course of the agricultural SCIENTIFIC AND PRACTICAL AGEICULTURE. 29 vessel, and vre may also very, properly regard agricul- tural science as the farmer's compass and chart, directing his vessel to the desired port. These, Avlien skillfully used, become of infinite value to the farmer. It would be as foolish for the farmer to reject the help of agricultural science as it -would be for the mariner to throw the compass and chart overboard; and, on the other hand, it would be as perfectly unreasonable for agi'icultural science to ignore farm experience as it would be in the mariner to unship his rudder and send it adrift. Of what avail would chart and compass be if the rudder (farm experience) be ignored. We have spoken of the cultivation of the soil as a manufacturing business; the soil, therefore, Ave must regard as the raw material from which the cultiva- tors have to produce the goods which are in demand, possessing those qualities necessary to bring the highest price in the market. Other manufacturers, who produce goods from raw material, such as wool, cotton, timber, iron, or clay, bring to their aid every appliance that scientific inves- tigation has discovered, with a view to economy in labor and the making of the very best fabric capable of being produced from the material used. It must be clearly evident that those who are to make the cultiva- tion of the soil their business should have a thorough knowledge of the particular soil which they have to cultivate. Every farmer must bring science and skill to his aid if he may hope to draw from his land the largest amount of produce, of the greatest value and lowest cost, and at the same time keep his land up to the highest state of fertility. The soil is generally regarded as merely earthy matter, devoid of all interest, except as a plant- growing source. If vre observe closely, and form an 30 ELEMENTS OF acquaintance witli onr soils, we very soon detect evidences of character, which close]y approximates animated existence, sucli as tempers, wills, and dispositions. "Jlie farmer's success frequently turns upon his familiar acquaintance with these points of character, yet few stop to inquire into the causes of these varia- tions; but when the inquiring farmer traces out these variations, thereby becoming more intimate with them, the soil becomes interesting, and seems to become invested with new attributes of life. Often have we been delighted and instructed by the conversation of the farmers wlio were the originators of the Eandolpli County Agricultural Society, in Illinois— men wlio had spent their agricultural apprenticeship in the pluvial climate of Scotland — while talking of their farm practice, each applying to his different fields distinct characters, as if they were living realities. One luid a field that was always hungry; another a field tlnit was sick and needed rest; another had one that was ahvays grateful, responding kindly for the labor given; another had one that was thin-skinned and shy ; another hud one that was stiff and stub- born; anotlicr had one that Avas sour and sulky and never kindly, etc. Each had tried his particular experiment for each peculiar character, keenly watch- ing effects and searching for causes. It is not to be Avondcrcd at tliafc tlicse men succeeded in making an ample competence, as all cultivators of the soil are sure to do who take the same lively interest in their land, and become familiar with its character. SCIEKTIFIC AND rfiACTICAL AGEICULTUKE. 31 CHAPTER XII. GEOLOGICAL INFLUENCE ON SOIL AND NATIONAL CHARACTER. The soil lias a history as well as a character, extend- ing over vast periods of time, and has seen many ups and downs; indeed its history gives us a series of inci- dents of thrilling interest, and, to contemplation, a subject full of wonders and an endless, awe-inspiring theme. The history of the human race records the rise and decline of nations and the progressive develop- ment of man's mental faculties ; that of the soil, the gradual evolution of that part of creation which made it possible for the inhabitants of the world to attain their present physical condition. Had the exterior crust of the earth been subject to no modifying causes since its first formation, there would have been no soil on its surface. There has been, however, a continuous series of changes going on, occasioned by the untiring and incessant operations of the various forces in nature, such as the rending of the earthquake, the upheaving of the volcano, and the universal operations of chemical and electrical agencies. Y/e find, by the testimony of the rocks, the record of the progressive work of creation, and the study of geology unfolds to the mind the indubitable proof of a design infinitely more provident and far-reaching than is possible for the highest human intelligence to fully comprehend or realize. 32 ELEMENTS OF TliG history of the rise and decline of nations cannot be fully understood by any one Avho is ignorant of the long chain of events Avhich had transpired, and slowly, but inevitably, prepared the conditions -which sur- rounded them, Avitliout any act or design of theirs, and which controlled them to an extent which was entirely overlooked by them. The controlling influence of the distant past can be no longer ignored. We must recognize how the physical condition of the earth's structure has in- fluenced political boundaries, and how the rise and fall of great empires, as well as their civilization and mental development, have been the unavoidable results of geological causes. A chain of geological events has shaped the destiny of the people of the United States to take the front rank of the great nations of the earth, both morally, mentally, and physically; with a capability of sur- passing those of the Old World, in proportion to its richer soil, vast mineral deposits, and more ex- tensive domain. Whatever the future may have in store for the American nation, it may be set doAvn as an incontro- vertible fact, that its destiny was part of the plan of creation, Avhcn its foundation was laid in primeval and lifeless seas: that built it up layer by layer with all the elements of wealth and power; enriching it at one time Avith valuable metalliferous deposits; at another period with lime or marble; at another Avilh coal; and at another with stratified rocks; that raised mountains to give variety to its scenery and climate; that denuded the mountain peaks and cold uplands atom by atom to furnish a fertile soil in a hospitable climate for the agriculturist; and that caused the great rivers to flow in the fruitful valleys to furnish highways for travel and commerce. SCIEHTIFIC AND PEACTICAL AGEICULTURE. 36 Creation to tlie geologist no longer means but a single act of illimitable power. It gives him a grander and sublimer view. The testimony of the rocks, when rightly interpreted, gives him evidence of a creation that is continuous, unfolding a design that is as illimitable in its origin as its final consummation transcends all human speculation. In short, geology reveals to man the Great Designer as a Being infinite in knowledge, wisdom, power, justice, good- ness, and truth. CHAPTER XIII. HISTOEY OF THE SOIL AlsTD WHEKCE DERIVED. The knowledge of the character and history of the soil will give the farmer instruction which he may utilize with great advantage, as the same forces are operating now as then which did the work. We have now come to that part where the questions naturally present themselves : From whence came the first soil? How "Was it formed? It will now be our task to answer these questions plainly and clearly. Soil is the result of the breaking down of rocks, with only one exception, that formed by vegetation, and com- monly known as peat. All over the world a continual change is going on by which the whole surface of the land is being gradually washed down into the Val- leys, or deposited along the level banks of rivers, or in lakes, or finally washed quite down into the seas. The wearing down of the stone Avork of our buildings fairly represents the mode in which rocks decay, and thus the fine mealy, earthy matter is produced 34 ELEMENTS Of which constitutes the soil. Through long geological periods, "which human investigation cannot name by figures, with any pretension to accuracy, this decay of the rocky surface has been going on without inter- mission^ and is still going on, so that we have now an abundance of this earthy inatter all over the face of the globe, amply sufficient for the wants of mankind. Geology further informs us that at one time, very far back in the world's history, the surface of the earth consisted only of rocks, which are called primitive rocks. There are large masses of these still remain- ing, which enable us to know exactly their nature and character. The surfaces of these rocks were pulver- ized by the gases existing in the air, just as they are pulverized now — which was the first soil upon this world's surface. Since then a series of changes have taken place, which geology reveals to us in part. It tells us that that first soil has been formed again into rocks, which again were reduced to soil, and again turned into rocks, and these changes have been taking place over and over again, as proved by the various geological formations. In the age in which one kind of primitive rock was soil, portions of that soil intermingled with portions from different primitive rocks, and in this manner soils have been modified in character; and these again have been greatly changed in their physical condition by animal and vegetable life. So you see the soil of the field has a descent and an antiquity very extraordinary and wonderful indeed, and full of instruction, especially to the cultivators of it. Now, as these reconstructions took place in this manner, wo should find in the primitive rocks the identical materials which we have in the soils of our fields, as these primitive rocks were the magazines SCIENTIFIC AND TRACTICAL AGRICULTURE. 35 from which all the supi^lies were obtained, and the various rocks, which were formed at later periods, are but reconstructions of the original materials. CHAPTER XIV. CONSTITUENTS OF PRIMITIVE ROCKS AND HOW BROKEN TO SOIL. Primitive rocks consist of three tolerably distinct groups, and are named by geologists as granite, syenite, and trap ; and by analyses are found to con- tain the following materials: GRANITE. SYENITE. TRAP. Silica 73. 59.8 43 Aluminia IG. 16.8 14 Ferreous Oxide 1.5 7. 15.3 Lime 1.5 4.5 13.1 Magnesia 5 3.G 9.1 Potash G. G.G 1.3 Soda 3.5 1,3 3.0 Phosphoric Acid, Sulphur, and Man- ganese Traces. Traces. Traces. Moisture None. 1.4 1.3 100. 100. 100. The composition of the original earthy matter, you will perceive, varied a good deal in character, and, accordingly, by the mixing of these materials, the character of the reconstructed rocks Avas affected; likewise marked variations in the soils, which were finally produced, are to be found and thus accounted for. It will be well now to notice how the crumbling of rocks is accomplished. The agencies are easily under- stood, and are at work now. It is very important that 36 ELEMENTS OF the farmer sliould know these agencies, as they are, even at the present time, lii.s valiuihle friends and lielpers. Every person has noticed tlio heautifnl, bright polish of the moukl-board of a plough after it has been at work for a time, particularly in sandy soil. When it is left in the field for a day or tMo, tlio beautiful polish becomes dim with rust. This rust is caused by the action of the air on the iron. Chemists investigated the matter, and solved the mystery, and discovered the depredators. They find it to be a very busy body, known to ns by the name of Oxygen, who is at the bottom of the mischief; they also discovered a companion of his, Avho is an able helper, and is known to ns by the name of Carbonic Acid. These two companions are as invisible as air, and are called gases. They not only attack iron, but they operate on rocks; it makes no difference to them how hard and tough they be. Now rub the rust off the mould-board and examine it carefully; notice Avhat a fine powdej' it is; this shows how powerful the operators are who did the work. The red rust contains iron, which was taken from the mould-board by these two agencies. Had the greatest force known to human skill been exerted on this metal, it could not have so completely powdered it as these two gases have done, without noise and almost without observation. Now, you will not be astonished Avhen we tell yon that they are equally mighty in pulverizing the hard granite. CHAPTER XV. AGENCIES WHICH REDUCE EOCKS TO SOIL. The action of water, and the change of tempera- ture, work also together in pulverizing the hard rock. SCIENTIFIC AND PKACTICAL AGIIICULTUEE. 3? These agencies, by being combined, their power to break down is amazingly increased. To demonstrate clearly to your mind the processes by Avhich all these agencies do their work so minutely, so completely, and with a power beyond any resistance, we propose to take a piece of granite, and watch, and record the prO' cess. It will be necessary, in order to give the work- men a fair chance to shoAV their powers, that Ave allow them an opportunity to reach it, and all that is neces- sary is simply to bring it to the surface. The instant it is there the Avorkraen begin the attack on all sides. If you Avill examine the table given in a former page you will see that granite, Avith all its density and hardness, contains two elements Avithin itself Avliich cannot Avithstand the agencies existing in the air. These tAvo elements are iron and potash, and are generally knoAvn, The oxygen and carbonic acid immediately begin their work on the iron and potash, and, after a time, we see a rusty mark on the surface of the granite. You may easily verify this fact by visiting a cemetery in Avhich there is a granite monument of a fcAV years standing. After the Avork has gone on for years Ave find small holes in the granite. These agents, like miners, have been driving "headings," and Avorking out "rooms," and sending off Avhat they have mined, thereby making the granite ready for the operations of the other tAvo agents, Avater and tempera- ture. The Avater penetrates the openings made by the "powers of the air;" then frost comes. You remember Avhat he did with the pitcher filled Avith water Avhen he Avent forth one frosty night — so he does Avith the granite pitchers; because Avater possesses the quality of grow- ing bigger when it freezes, and bursts the AA\alls enclosing it. The little fragments are held there till a thaAV comes, Avhen they are Avashed doAvn from 38 ELEMENTS OF their former j)osition; the openings are tlins enlarged, making room for a greater number of tlie airy work- men; and thus the work goes on Aviili redoubled capacity and with energy untiring. No resting with these miners to take a smoke, or retiring from the work to take refreshments. CHAPTER XVI. HOW HOCKS ABE CRUMBLED WHICH HAVE KO IROIST MATTER IK THEM, You may say, "Now I understand how oxygen and carbonic acid, assisted by frost and water, are enabled to break doAvn and pulverize granite and similar first rocks, but I cannot see how they can effect a like result with rocks in which there is no iron to enter into an alliance with them to accomplish the Avork of demolition, no traitor in the camp, if we be allowed the expression." We know of no rock besides fire-clay rock which, when blasted in the mine, is nearly as hard as whinstone, that is so free from iron particles. This rock is valuable just in proportion as it is free from all iron matter, consequently the atmospheric agencies have not an opportunity of entering into an alliance with their old colleague — iron. Having long heard of the Mt. Savage fire-brick, so greatly famed for its ability to endure intense heat in furnaces Avithout crumbling or fluxing, Avhich it could not do if even an appreciable quantity of iron were present, upon a late occasion we visited the mines from which the "clay" is obtained for the purpose of testing this very subject. By the kindness of Mr. Findlay, foreman of mines, Ave Avere taken a long dis- tance under ground, entering the opening in the side SCIENTIFIC AND PKACTICAL AGKICULTURE. 39 of the mountain in a tram-way car, the tram-way run- ning nearly horizontal to the "face" of the rock, where tlie miners, with drill and sledge, were diligently making holes in which to put powder to blow it out from its ancient bed, where it had been sleeping quietly for so many ages. The sharp chinking sound made by the steel drill and sledge, gave testimony to the hard- ness of the rock. We examined the fine dust taken from the drilled hole, and, rubbing it ])etween the thumb and finger, easily detected its fragmentary condition, by its fine gritty feeling. We Avere there shown a stratum of rock, which was so free from any trace of iron as to be pronounced by the chemists "pure fire-clay rock." We procured a specimen from this sti-atum, and, after submitting it to the rains and the frosts for about two months, it was completely reduced to atoms; on testing it between the thumb and finger, it felt as smooth and fine as the particles com- posing grease. There was no fragment, no grit — the demolition was complete. Although no ferreous matter was present to join in conspiracy with the oxygen and carbonic acid of the air, yet water found an entrance, and permeated the specimen entirely, which we had taken for a test; and as water will not be restrained from growing bigger when it freezes, so the water in the specimen froze, and, in its effort to grow bigger, separated the rock particle by particle. We also visited the brick works of the same company in the village of ML Savage, Md., to examine the rock- crushing process. Mr. Clifford, foreman of the works, very kindly showed and explained the operation. The rock is subjected to the crushing force of an iron roller of immense weight. When it is of sufficient fineness it falls through a sifter into a receptacle below, and taken 46 ELEMENTS OF from there by an elevator, and passed on to undergo the operations of mixing with water, moulding, drying, and burning. So complete, apparently, is the rock broken down, that the clothes of the men attending the crusher are as white as those of a miller; yet when that wliieh was brouglit up by the elevator was examined, it was found to be cliiefly fragmentary. In the contemplation of this work we cannot refrain from exclaiming: Man's works, how powerful they are! But thoy fade into insignificance when contrasted with the complete and perfect work of the cpiiet operators appointed to do tlic will of the Great Designer. CHAPTER XVII. THE BREAKING DOWN OF EOCKS TO SOIL. Some may think that this breaking down of the primitive rocks could only take place to a very limited extent; but if we reflect for a moment and bring before our mind the time when "dry land" first appeared, and there was no soil, and think of the immeasurable surface presented to the air agencies, and the vastly greater quantity of carbonic acid in the air then than now, together with the other agencies, water and temperature, we shall understand, in a measure, how illimitable the power was. The work went on much more rapidly with the secondary rocks and later formations, they being much softer; and, as the work of demolition went on, the rocks got covered more and more, and presented less and less surface to the air, and were placed beyond the influence of all the pulverizing agencies; thus tlie work of breaking down gradually decreased, and finally stopped, till again thrown up into the air. SCIENTIFIC AKD PKACTlCAL AGIlICtJLTURE. 41 As soon as there was sufficient soil made for '"'man to till and dress it," and employ his skill and knowl- edge in the production of food, and all things necessary for his comfort, the reduction of rocks gradually diminished because the work was sufficiently advanced to meet the necessity of the case. It now remains with the intelligence and skill of the farmer "to make the soil fruitful and bring forth abun- dantly." We may mention another agency ^^■hich helps to break and pulverize some kinds of hard rocks. If a piece of polished marble be covered with clean sand, and a few seeds of mustard, or other seeds, be placed in it, and then put in a moist, warm atmosphere, the seeds will soon germinate; after allowing the young plant to grow for a short time, and then clean everything from the marble, minute holes will be found in it, which were made by the acid sap of the young roots eating into it to obtain food. The roots of trees, too, entering crevices of rocks, frequently split off great blocks as they expand in thickness; even paving-stones have been known to be broken by the growth of tree roots under them. The In-oken and powdered rocks formed in these various ways are washed down the slopes of the moun- tains by rains into the rivers; in many flat plains the rivers overflow frequently, and spread their material over the land. In this case we see a sorting and dis- tributing action taking place. When a river rushes down as a torrent it carries with it mud, sand, gravel, and even large stones. But when the descent becomes less, so does the swiftness of the current, and the large stones are first dropped, aftervrard the gravel, then the sand, and, lastly, the fine nmd is distributed over the plain, and only deposited where the current has almost 42 ELEMENTS OF or quite ceased. In this "vviiy beds of gravel, sand, and clay are formed, thus producing soils differing from each other. Great quantities of the same materials have been carried into the sea, and aj)parently lost; but beds which were formed in that way, many ages ago, have been since lifted up by earthquakes or other movements equally powerful, and from these beds many of our soils are formed. When we recognize the power of nature's forces exist- ing in the air, including temperature and moisture; the action of the roots of plants themselves; the tread of animals; the rushing rivers causing rocks to grind each other; the glaciers, these ice-rivers fed by the ever-accumulating snow, descending mountain gorges, with slow but irresistible force, smoothing, grinding, and striating the rocks in their Avay; the volcano, throwing out the molten lava and ashes; and the icebergs of the glacial period, which, when the land was being elevated by some internal force, were arrested in their course, and descended the mountain sides, smoothing hills and valleys among which they passed, and finally melting and leaving their cleiris, as mounds of sand, gravel, or boulders; all these gave their contribution; and the varied particles thus inter- mingling, the formation of the different classes of soils ceases any longer to be a subject of wonder. CHAPTER XVIIL THE PHYSICAL COMPOSITION OF SOILS. We have now learned that some soils have been carried a long distance from the place where they were formed, and may, therefore, be very different from SCIENTIFIC AND PRACTICAL AGRICULTURE. 43 the rocks underlying them, while others have been more quietly spread out by the rain upon and among the rocks from which they are derived. These are called native or local soils (soils in situ) ; the former are said to be transported soils. The great variation in character renders it neces- sary that Ave should be able to distinguish soils, so that we may be able to describe them Avith some degree of accuracy. For this purpose sand and clay have been selected for the sake of contrast, io enable us to divide them into two distinct groups. In the sand on the seashore Ave have the one in per- fection; and in the clays used for pottery Ave have the best specimen of tlie other. The one, Avlien it is mixed Avith Avater in a vessel, falls to the bottom rapidly; the other, Avhen it is mixed Avith Avater, falls to the bottom sloAvly, rendering the Avater muddy for a considerable length of time. There are other marked differences in their character; for example, sand, Avhen it is Avet, is hard to the touch; it has little cohesion; it cannot be formed by the hand into any definite shape; it is gritty; it alloAvs water to pass through it rapidly, and is firm to the foot. Clay, on the other hand, Avhen it is Avet, is the direct opposite in all these respects; it is soft to the touch; it has great cohesion; it can be moulded into any definite shape ; it is soft and smooth ; it holds AA'ater upon its surface, and is slippery to the foot. If a soil consists of more than three-fourths sand, it is called a sandy soil; if, on the other hand, more tliaii three-fourths of its weight is clay, it is called a clay soil. A mixture of about half sand and half clay, it is called a loam. If there is rather more than half sand, it is called a sandy loam; if rather more than half clay, it is called a clay loam. All these soils may have 44 ELEMENTS OE* II small quantity of lime and vegetable matter, making them "rich." A soil -which contains nearly a quarter of its "weight of lime, is called a marl ; if the rest of the soil is mostly sand, it is called a sandy marl; if mostly clay, it is a clay marl. Soils which contain a large quantity of lime arc calcareous soils. A soil which con- tains a large portion of vegetable matter, is called a peaty soil. These differences among soils may be tabu- lated as follows: Sandy Soil f Sand I sand to all sand. \ Sandy marl ij sand to ] lime. /Clay f clay to all clay. ^^'^^ ^°'' Iciay marl f clay to i lime. (Sandy loam ^ sand to ^ clay. Clay loam f clay to ^ sand. Sandy loam f sand to ^ clay. Calcareons soil \ lime to all lime. Peaty soil ]^ humus to all humus. Each of these soils can be again divided into poor, middling, and rich, or fertile, according to the quantity of the other matters contained in it. Thus, a loamy soil, containing lime and vegetable matter, as well as sand and clay, is richer than one containing sand and clay only; and, generally speaking, the most fertile soils — that is, those yielding the greatest amount of plant food' — are those which are composed of a fair mixture of all the four constituents. A cubic foot of dry sand weighs about one hundred and ten pounds, A\liile the same bulk of dry clay weighs only about seventy-five pounds; yet a farmer calls a sandy soil light, and a clay soil heavy. His judg- ment is Ijased upon the ease or difficulty of working the soil more than the actual weight. The par- ticles of s:iud are eunii)aralively large, with no tendency to stick together, or to the* implements with which it is worked, so that a plough easily moves between the SCIENTIFIC sVKD PRACTICAL AGRICULTURE. 45 grains; and the soil is called light because it makes liglit Avork. In a clay soil, however, the particles are so fine, and have such a tendency to stick to one another, and to the implements passing between them, that much difficulty is experienced in moving and separating them; this is heavy Vvork; therefore, this kind of soil is said to be heavy. CHAPTER XIX. CAPILLARY ATTRACTIOiq" AS AFFECTED BY THE PHYS- ICAL CO]!fDITIO]Sr OF THE SOIL. The power of holding moisture by the soil is another important subject for the farmer, which we Avill now briefly investigate. If one end of a fine glass tube be dipped in water, the water rises i-n it; and the finer the tube the higher above the surface the Avater rises. This is called capillary attraction, because of the hair- like fineness of the tube. The same action takes place Avherever there are small spaces betAveen substances, as in a sponge, the Avick of a lamp, or a lump of sugar — all of Avhich have the poAver of draAving and holding Avater in the little spaces they contain. This is a very impor- tant property in soils. The Avater in a saucer under a floAver-pot containing soil is taken up in this Avay, rising up to a greater height if the spaces are small, and to a less height if the spaces are large, and staying there Avithout falling back. In coarse sand it Avould not rise far; but in clay, Avhere the particles are finer and closer, the capillary attraction is greater, and the Avater rises much higher. NoAV suppose one hundred pounds of dry sand to be placed in a vessel, with holes in the bottom, it will be 46 ELEMENTS OF found to receive and hold twenty-five pounds of water before it begins to drop; then fill it with the same (piantity of loam, and it will be found to hold forty pounds; if filled with clay loam, it will hold fifty pounds; and if filled with clay, it will be found to hold seventy pounds of Avater before beginning to drop. Clay soils likewise absorb more moisture from the atmosphere than sandy soils. If one hundred pounds of sand be spread out when the atmosphere is moist, but rainless, for twelve hours in the night, it will absorb only a few ounces of Avater ; if clay loam, two and a-half pounds; and if clay, nearly four pounds of Avater. The influence of capillary attraction is beneficially felt during the period of the groAvth of plants. IIoav- ever Avell a soil may be supplied Avith the food required for a crop, plants only can make use of it in a liquid form; the presence of Avater to carry the food into the circulation is jUSt as necessary as having the food there. During the summer months, Avhen the sun's rays are shining strongly upon vegetation, large quanti- ties of Avater are needed, and it is at such times that this system of attraction proves its utility, by bringing up to the roots refreshing supplies of Avater, finely divided, like a diffused mist in the soil, Avhich enables the groAvth to push on luxuriantly. But it may reasonably be asked by some, Avho may think of drainage in this connection: What is the use of draining water from the soil if it be carried back by this capillary attraction ? We shall try to giA'e you light on that subject in another chapter; but, in the meantime, Ave shall ask you to reflect, and find out the reason for the flower-pot having a hole in the bottom, and Avhiit Avould be the consequence if no hole Avas there. SCIEOTIFIC AND PRACTICAL AGRICULTURE. 47 CHAPTER XX. PHYSICAL COKDITIOJSr OF THE SOIL. The influence of the mechanical or physical concli- tion of the soil is a subject fraught with the greatest importance to the agriculturist. We may take it for granted that all acknowledge the need of air, warmth, and moisture to enable a plant to grow. In order that the seeds may have air, a loose condition of the soil is necessary. For this condition sand is better than clay, because the spaces between the grains are larger, and thus allow the air to enter. But if these spaces are too large, there cannot be enough of water retained in the soil, and the young plant will consequently suffer for want of moisture. Again, if too much moisture is retained in the soil, it not only shuts out the air, but it becomes cold, and deprives the plant of warmth, thus preventing the plant from receiving the second requisite necessary for its growth. From these facts we are forced to the conclusion that the best kind of soil, in regard to its physical condition, for a seed-bed, is a mixture of sand and clay — that is, a loam, not so close and fine in its grains as to prevent the free access of air and warmth, and not so open as sand, allov/ing the Avater to run through it too quickly, or having little power of capillary attraction. We may now conclude this subject of the physical condition of soils by briefly referring to the other two agencies that have contributed matter found in our agricultural soils. In all cultivated soils you will observe a black substance intermingled with the 48 ELEMENTS OF mineral matters; it is generally known by the name of "vegetable mold" or "Immns;" this is contributed chiefly by the air and the sea. It -will be learned from the above that the physical condition of soils is entirely due to the proportions in -which sand, clay, lime, vegetable matter, and mineral fragments enter into their compo- sition. CHAPTER XXI. CHEMICAL ANALYSES OF SOILS. There is another section of the work which treats of the composition of the soils, and this shows us Avhat bodies are found in them, in what proportion, and in wliat conditions of solubility. These are determined by chemical analysis, which is very difBcult even for professional chemists to do. It is generally looked upon as something which may be easily done, but it is one of the most complicated and troublesome analysis which has to be carried out. The information thus to be obtained is of immense value to the farmer, provided it be carried out in an exact, correct, and proper manner. Among the first things vre learn by this examination of the soil is, that a very small portion of the best soils is really ready with food for the immediate use of plants. That which is ready for immediate service is called the active portion of the soil, whilst the remaining store is known as the dormant or sleeping portion. Here then we get our first chemical division of the soil, viz.: The active matter and the dormant matter. The dormant matter is only sleeping, and while in that condition it is valueless, yet it is really of great value. It awaits the intelligent farmer to arouse SCIENTIFIC AND PEACTICAL AGEICULTURE. 49 it from sleepi when it will become as the reserve forces of un army, to be called to duty when the active forces are becoming exhausted. It would be imprudent to allow those on active duty to be completely exhausted before calling up the reserves; but on very many farms the reserves arc never called up, and the land in consequence is completely Avorn out and exhausted, while yet containing a vast amount of fertile matter, which has been permitted to remain in peaceful slumber in the soil. The chemical analyses of soils have been very gener- ally carried out, as if all the fertilizing matters present in them were at the service of the growing crops. It was thought that if a farmer knew what his crop wanted, and also what he had in the soil, it would be an easy matter to supply the wants by a manure con- taining the particular ingredients needed. In that hope he was bitterly disappointed, because the analysts disregarded the well known fact above mentioned, and analyzed the soil as if the active and dormant matters were in the same condition, and were all ready for the use of plants. If a farmer is to be benefited by an analysis of his soil he must know what he has there that is avail- able for his crops ; there must be a distinct line drawn between the active and dormant portions of the soil; then he may get information which will be valuable for his guidance. CHAP TER XXII. AGRICULTURAL CHEMISTRY — NECESSITY FOR DEEP PLOWING. You have been shown that plants require a great variety of different kinds of food for their full and 50 ELEMENTS OF perfect growth. Not one of these bodies is avaihible as phint food, unless it is in such a condition as to be easily dissolved in Avater, aided by some organic acid. Thus water, aided by a weak acid, is the vehicle by which the food passes from the soil into the plant. Solid matter which will not dissolve in such Avater may be useful mechanically in giving an abode to the plant, but cannot enter its organism. It is of the utmost importance to the farmer to inform himself as to the possibility of making the dormant matter take the active form. This is quite possible, and under good cultivation it does take place to a large extent. The friendly helpers are the atmospheric agencies, which Avere so effective in break- ing doAvn the rocks into soil. Having increased the amount of surface soil by deep cultivation, Ave find the rain Avater carrying its supply of oxygen and carbonic acid, persistently bring- ing plant food into solution, and passing it over to the safe custody of the silicates in the soil. In this Avay large quantities of insoluble matter are brought into an active state, and in good soils Ave find it Avell and carefully preserved until the groAving crops demand the supply. It must noAV be evident, that just in pro- portion to the extent that Ave alloAv these atmos- pheric agencies to act upon the soil and subsoil, so Ave shall the better enable them to change the dormant matter, Avitli Avhich it is permitted to mix, into a condi- tion available for plant food. These agencies accom- plish a Avork Avhich is equivalent to the purchase of so much manure. It is, therefore, very desirable for the farmer to give them every opportunity for Avorking in his interest. The farmer can best facilitate this Avork by a thor- oughly good and timely cultivation of the soil. SCIEKTIFIC AKD PRACTICAL AGRICULTUKE. 51 Let ITS compare, for the sake of making plain and clear, what we mean, two fields having similar soils — say heavy, clay soils, similarly located or side by side. In the one case, we will suppose the field has been deeply plowed in the fall, and laid up as roughly as possible, so as to expose as much surface as may be attainable to the action of the sun and air. In the other case, the plowing has been postponed till spring. In the one case, we will see that the friendly helpers have been at work, promoting the change of any sour matter, converting it into wholesome plant food, bring- ing some of the dormant matter into an active form, and making the soil loose and friable — these being all favor- able to the growth of vegetation. All this has been done by the action of the oxygen and carbonic acid in the air, assisted by water and temperature. In the second case, no effort was made to let these agencies bring about the same changes ; but, as the soil lay in its solid bed, and probably water-soaked, it was really becoming less fit for plant growth. In the one case, the land was plowed up in the spring tough and sour, requiring more labor than the other; yet it was not brought into such a productive condition. In the other case, we have a luxuriant growth of crops, at a smaller expenditure of work ; while in the other case we have the work of nature's agencies rejected, and the result is far from gratifying and very expensive. It is well that we should value highly these friendly helpers, and that we should do all we can to give them the best opportunity to do their work. The advice of the old farmer is directly to the point: "Marry the air and the soil, my son, for unless they be allowed to intermingle and join with each other freely, the soil will not bear abundantly." 53 ELEMEJ^TS OF CHAPTER XXIII. DRAINAGE A MEAKS OF GETTING AIR INTO THE SOIL. The drainage of the land is anotlicr means adopted to admit the atmosphere to the soil. The common idea, that land is drained simply to remove water, is too limited; it does a great deal more. The first effect we see, of course, is the running away of the water; but water would not flow away if air is not admitted. This may be easily proven by the tapping of a barrel of cider, or any other liquid, near the bottom; in order to draw it, a hole must be made at the top of the vessel into which the air will rush as long as the liquid flows. The drains, therefore, allow the water to run away, because they can draw air into the soil; conse- quently we drain land as much for getting air into the land as for taking water out. The benefit arising to the soil is apparent; for wherever air is admitted, its oxygen and carbonic acid immediately commence work, and go silently on day and night, changing the dor- mant matter in the soil to its active form. The farmer who treats his land to thoroughly good cultivation and drainage, will be amply rewarded Avith the rapidly improved fertility of the soil. Subsoiling the land produces the same condition, by stirring up the soil which lies beneath. This is a means whereby the passage of water through the soil is rendered more easy, Avhich is followed by the air, and, as a consequence, more of the soil comes under its influence, provided. SCIENTIFIC AKD PRACTICAL AGRICULTUEE. 53 always, that the great agricultural flower-pot has a hole in the bottom. Another advantage arising from the passage of the air is, tliat it sweetens the soil by changing the sour and unhealthy decaying vegetable matter in it, to the higher form of carbonic acid, Avhich is one of the farmer's friends. The yellow oxide of iron, which is a poison to plants, becomes, by the action of the oxygen in the air, another helping friend to the farmer. In addition to all these, there is yet another servant ready to aid him, and that is the ammonia in the air. This is a yery expensive substance to purchase ; yet it exists in the air, and a very considerable supply can be gathered from it by the soil, if it is properly aerated. Now, you will see that there are many servants wait- ing to help the farmer to make his land more fertile, if he will but receive their ever ready and willing assistance. These ask no wages; they require no rest; but day and night they are ready to 'work if they are permitted to do it. Water-soaked land repels all these friendly helpers, as well as solidified land. CHAPTER XXIV. THE ACTIOIsr OF HEAT AKD OTHER ADVANTAGES OP DRAIKAGE. In order to understand the beneficial effects of drain- age more clearly, we shall investigate the laws governing the action of heat, because we may not be able to 54 ELEMENTS OF grasp the ideas gatisfactorily unless "sve start with ^ knowledge of first principles. Substances that are warmer than their surroundings, conimunicale their excess of heat in tliree distinct ways: (1) By conduction. (2) I3y convection. (3) By radiation. To demonstrate the conduction of heat, hold one end of a brass wire between tlie thumb and linger, and the other end in the flame of a lamp; the experiment will terminate suddenly. Now take a piece of dry wood the same size, and hold it in the flame; it will become red hot and blaze without burning the fingers. The heat is led along the brass wire; it makes no difference whether it be held to the flame upwards, downwards, or sideways; the wire is, therefore, said to be a good conductor, and wood a bad con- ductor. The conducting power of different substances varies considerably. Metals are good conductors. Silver is recognized as the best conductor, water the lowest, and clay the next. The ratio of their con- ducting power may be stated thus: Silver, 1,000; Avater, 1 ; clay, 4. Convection is the conveying of heat by the air, gases, or liquids. Tlie common notion, that heat ascends, is based upon the action of heat by convec- tion. Water, as we liave stated above, is one of the very poorest conductors of heat; yet we all know that heat is transmitted through it, as wlicn we boil Avater in a pot. If, however, we placed water in a fire-clay pot, and apply the heat to the top, wliieh is tlie way heat is applied to the soil, tliat "waited-on pot" would be long in boiling. The upper film of water receiving the heat would remain lighter than tlie rest, SCIENTIFIC AND PRACTICAL AGRICULTURE. 65 and retain its position; and, being a poor conductor of heat, it parts slowly with its heat to the water beneath, which remains cold. Its warmth is not increased very much by the pot, because its material is also a poor conductor. "When the heat is applied to the bottom of an iron pot, the hot metal of the pot heats the bottom film of water by direct contact; this film expands, becomes lighter, and rises through the water above it, warming it by contact, and speedily causing the "pot to boil." Radiation is a flinging off of heat in every direc- tion. Bright, shining surfaces are profligate radiators and poor absorbers of rays of heat; they, therefore, cool quickly. The soil is one of the best absorbers of heat when it is drained of superfluous water; but if, however, stagnant water has to be evaporated from it, tlie heat is carried away and the soil remains cold. That evaporation has a cooling influence, you may easily prove to your own satisfaction by wetting your finger Avith water in a warm room and hold it up; you will feel the cooling influence; if made wet Avitli spirits, the evaporation will be more rapid and produce a cooler feeling; and if ether be used, which almost instantly evaporates, it Avill produce a still cooler feeling. Ice may be produced by evaporation, so great is its pOAver of carrying away heat. According to the natural laAVS governing the effect of heat on Avater, it contracts gradually in volume until its temperature is about thirty-nine degrees; below this it begins to expand until it reaches thirty-two degrees, Avhen, under ordinary conditions, it becomes solid, and, in doing so, undergoes a greater expansion, eight volumes of Avater becoming about nine of ice. 56. ELEMENTS OP The expansion of water below thirty-nine degrees has very important results. It prevents all our water supplies being frozen up. If water contracted continuously till it reached the freezing point, we should have all the water in our lakes reduced to that temperature before freezing commenced on the surface, and a very brief continuance of freezing weather would solidify the whole mass ; but, as it is, the water at thirty-nine degrees, being most dense, sinks to the bottom and there remains; while the water at thirty-two degrees, being the lightest, remains on the surface, and ice, being a bad con- ductor of heat, preserves the too rapid cooling of the water beneath. We have, consequently, a gradual freezing of the surface doAvnwards. We understand now how a proper system of drainage favors the passage of water through the soil, and passes it aAvay to some lower level. It will also be easily un-> derstood that the passage of warm air through the soil must, of necessity, raise its temperature by its heat being transferred to the land. This is a very constant source of heat during the months when the crops are in a very active state of growth, and is a means of making a distribution of the heat to a greater depth and more equally throughout the soil. The warm rays of the sun falling on land soaked with stagnant Water, or the warm breezes passing over it, do not warm it, as they would drier land. The stagnant water has to be made to pass away as a vapor before the warmth of the sun or tlic warm breezes can exert a stimulating influence on the soil. The cause of this will be easily understood when we remember What a quantity of heat is required to change Water into vapor. The consequence is that wet and iindrained SCIENTIFIC AKD PRACTICAL AGRICULTURE. 67 land is found to be cold and unproductive ; the crops are always kept back in their growth, and are much later in coming to perfection than those grown upon drained land. The attraction by the soil, where drainage keeps it comparatively dry, for the heated rays of the sun is proven to be very great. On the fallow the portion of the air coming in contact with the soil becomes expanded and struggles upward through the superin- cumbent cooler air in visible wavy lines. The soil is also a slow radiator as well as a good absorber of heat. On this account the herbage on drained land is much less liable to be injured by spring frosts. This property enables it to keep up its temperature and prevents its being reduced to the freezing point for a considerable length of time. The power of the soil for absorbing a great quantity of heat and parting with it slowly has long been recog- nized by the farmer. When he takes a journey in his wagon or sleigh on a cold winter's day, he does not heat a block of iron or Avood to keep his feet warm, because he is aware that, although he can warm these materials to a high degree, they would part with their heat so rapidly that their usefulness for heating pur- poses would soon be gone; but he takes a brick, which is simply soil compressed and burned, and heats it up to a high degree, then rolls it up in a piece of carpet, and his feet are kept comfortable for a long time, because the brick parts slowly with the heat stored up in it. The following table is taken from Jamison's prize essay "On the Action of the Atmosphere in Newly Deepened Soil in Scotland," showing the increased temperature of the soil and subsoil, being 5B ELEMENTS OF important us affecting vegetation, and likewise valnaLle because it is reliable and instructive on this subject: TAKEN IN PEUl'ECTLV I'lNE AVEATHER. Elevation of tem- perature by the Moan Toinporaturo. pun's rays on a Earth's Surlaco. Air In Shade. Oralued surface. Degrees. Degrees. Degrees. January 54.1 24.0 29.5 February 86.2 43. 43.2 March 99.5 4G.G 52.9 April 121.G C1.7 59.9 May 131.2 G7.3 G3.9 June 139.8 75.2 64.G July 14G.3 81.3 65. August 130.1 G8.9 G1.2 September 119.8 68.0 51.8 October 80.8 42.8 38.0 November 72.7 40.1 32.6 December 59.2 35.G 23.6 The beneficial effects of drainage for soils naturally water-soaked, need no further comment, and may be briefly summed up. The temperature of the soil is raisetl; porosity for moisture, though not for wet, in- creased; disintegration is affected, and nutritive solu- ble substances liberated; atmospheric gases absorbed; injurious substances changed bo as to be positively beneficial to vegetation; and the wasteful surface flow from fertile fields reduced to the minimum. CHAPTER XXV. OBJECTIOKS TO DRAINAGE, AND TllEIR FALLACY. Objections have been made to underdrainage, which will now occupy our attention briefly : (1) It is urged that the Avatcr is carried away from the land too SCIEIfTIFIC AND TKACTICAL AGKICULTURE. 59 quickly, causing the overflow of rivers. (2) Because it is not allo-vved to remain long enough on the land to XDercolate down through the soil to supply springs. If wo reflect for a moment, Ave cannot fail to see how erroneous is the first objection; nnderdrainage increases greatly the capacity of the soil to hold water by giving it a larger area for dis- tribution. A field which is underdrained, therefore, holds more water before reaching the point of satura- tion than a field of the same character can possibly do without being underdrained; hence, a less flow of water from the drained land in proportion to the amount of rain frilling upon it than from the undrained land. When the Ohio Eiver overflowed its banks a few years ago, and wrought guch great destruction, drainage was held responsible in a great degree; but when reflec- tion had time to assume its sway, it was discovered that all the w^ater flowing from tile drains into the river and its tributaries, would not have much more than filled a good sized mill-race. These, Ave consider, to be sufficient to dispose of the first objection; and as for the second, the groundlessness of it will be apparent when we remember how small the area which is, and always will remain, undrained by artificial means. The clearing away of the forests, and the surface flow from undrained lands, may be set down, Avithout fear of successful contradiction, as the chief causes of destructive floods, and, we may add, excessive droughts. Just in proportion to the pro- tection of the earth's surface by trees from the sun's rays, so is the gradual melting of the winter's snoAvs ; without this protection, spring thaAvs are rapid, and torrents ensue. 60 ELEMENTS OF Tlie sun's rays in passing ilirougli (lie air do not heat it; the air is AvaruR'd by radiation from the earth's surface; and tlie greater the degree of heat wliich tlie air readies, the greater is its capacity to liold moisture; tlierefore, if air bo saturated Avith moisture to tlie point of precipitation, and afterward passes in summer over a denuded surface, it being greatly heated by radiation from the bare sur- face, its capacity to hold moisture is increased, and no longer remains at the point of precipitation, but passes away to descend as rain Avhere the radiation is modified by the forests and the land well covered by vegetation. The farmers in the prairies will tell you mournfully, "that the showers, when most needed, take to the timber and follow the creeks." This is an observation frequently made by the prairie farmers. Another important benefit is brought about by thorough drainage, which of itself is sufficient reward for all the labor and cost in the construction of drains, and that is the healthful and salubrious condition of the atmosphere. Where is the country which abounds Avith malaria, bilious fevers, and agues? It is not in the mountains Avhere the land is drained by nature, and the sparkling waters gush forth from the drains of nature's own making, and the "living waters flov,-;" but all these ills of life prevail in the country where the land is water-soaked, having no liolc in the bottom of the great agricultural llower-pot, and where water stagnates in sloughs and ponds. The health of man, and beast, and herb, are all benefited by drainage. The approved method of draining is: (1) Bore and dig the ground to ascertain the kind of soil to the depth of three or four feet, so as to knoAV how fax SCIENTIFIC AND PRACTICAL AGRICULTURE. 61 apart the drains should be. (2) Take the necessary levels. (3) Lay off the lines of main and minor drains. (4) Make a map of the proposed work. To put straw, brush, or stones on the top of the tiles when placed in position in the drain, is bad practice. Fine earth should be closely packed on top of the tiles to cause the water to enter the drain at the bottom. The greater the quantity of soil that water has to percolate through before it enters the drain, the better is its opportunity to pass over to the safekeeping of the double silicates the plant food it holds in solution, Water from such drains, when caused to overflow a meadow that is itself well drained, will add little or no plant food to it. This was at first doubted, and a case has been cited v/here a meadow was overflowed with water from the drains of a field on a higher elevation, which was suffi- cient to keep up the power of the meadow to produce good crops of hay without its receiving any other fertilizer; but upon investigation it was discovered that some of the drains tapped springs at their source, and conducted the water directly to the meadow, which gave up the plant food it held in solu- tion to the soil it had to pass through. You will remember what we before told you that gome kinds of bright, sparkling, spring water hold the elements of plant food in solution in sufficient quantity to fertilize the land through which it percolates. The springs in this case were enriched with the inorganic substances of plant food, and thus fertilized the soil, which accounted for this drain water enriching the land. The surface flow of water from a fertile field which spreads over another field well drained will carry an ample supply of fertilizing substances to it, which will make it yield abundantly; but water, 62 ELEMENTS OF after percolating tlirough a loaiii or clay loam soil into drains, is deprived of its fertilizing ingredients by the double silicates, and is thus rendered "worthless as a source of plant food. The surface flow of water from cultivated fields is the naaximum of evils to Amer- ican husbandry of the present day. CHAPTER XXVI. ORGANIC CONSTITUENTS OF THE SOIL. We may now consider the organic constituents of the soil. The quantities existing in the soil differ consider- ably; but they are present in all good soils. If a portion of soil be burnt on an iron plate, a smoke will be produced from it; and if weighed before and after burning, we will find that it has lost weight by the burning. The loss represents the water dried out, and the organic matter burnt off. If we examine the new soil produced by the atmospheric agencies from the rocks, we shall find very little organic matter in it, and in some cases none. The fact is, that only the lower orders of vegetation grow in it; but as these die, their remains mix with the soil in ■which they grew. After this has been going on for successive years, the soil becomes somewhat enriched by the rem.ains, when it becomes fitted to produce plants of a higher order, and these add still more vegetable matter to the soil, so that it finally becomes mixed with a great deal of organic matter, which was produced upon its surface, and is thus prepared in a natural way for growing a crop. The term organic matter is generally applied to those portions of the soil Avhicli at some time or other SCIENTIFIC AKD PRACTICAL AGRICULTUEE. 63 have been organized, and have performed functions of animal or vegetable life. Organic matter con- sists cliiefly of substances draAvn from the air, and the carbonic acid is the cliief contributor. As we carry on the ordinary processes of cultivation we increase the quantity of this organic matter. In fact, the general tendency of cultivation is in the direction of adding to the soil organic matter. Some crops are especially valuable, because of the organic matter they add to the soil, such as clover and green buckwheat, when plowed under. An ordinary observer, in looking at a grass sod, can see the numberless small roots with which the turf is so full, and the black color gives evidence to the expe- rienced eye of earlier supplies of rootlets which had decayed in the land. We shall now examine into the beneiits which the soil derives from this organic matter: (1) It has a tendency to give a freedom to the soil, which enables the roots to penetrate it in search of food. Stiff clays which, from the extreme fineness of their particles, have a tendency to become firm and com- pact, are greatly benefited by the intermixture. In the case of sands it discharges an equally useful duty. In these soils there is no difficulty of the root penetrating the land; but there is a want of firmness, and in such cases the increase of organic matter is very valuable; in short, in every kind of soil the intermix- ture of organic matter is beneficial — excepting peaty soils, of course. (2) It increases the power of any soil for absorbing moisture and gaseous matter from the air. Nor must we overlook the fact that such organic matter is one of the means whereby manure and plant food are held in the soil, particularly sandy soils, when the previous condition of the land would 64 ELEMENTS OP have allowed it to be washed away and gone beyond tlie roots of tlie plants. It has become the practice with intelligent cultivators of the land, who have light soils having little power to hold the food in a soluble condition, to apply the farm- yard manure to the young clover, Avhich encour- ages a strong, rich growth, and thus it preserves the greatest portion of the plant food, which would other- wise have been washed away from the soil. Tlio great amount of rich clover roots which decays gradually during the growth of the following crop, yields up a large store of fertilizing matter, just as it is needed by the crop. CHAPTER XXVII. BAD CHARACTEES OF SOILS AKD HOW TO REMEDY THEM. We may now consider the characters of soils, to which we alluded in a former chapter. This is very impor- tant, because these characters of fields indicate certain opinions of intelligent practical farmers. We shall endeavor to show what the farmer means by say- ing that a certain field has a hungry soil. Because a particular field is always in want of nour- ishing materials, the farmer says of it that it is hungry. Sands and gravels belong to this class, because th pounds are very unlike any one of the elements from which they are formed, CHAPT ER X XXVIII. THE BINARY COMPOUNDS AND THE FORMATION OF THE SALTS. When two elements combine it is called a binary compound. These are very important to agriculture. They are generally divided into two groups — acid oxides and bases. Water lies between the two groups, and acts as an acid oxide to the bases, and as a base to the acid oxides. COMMON NAME. FORMED FROM. Carbonic Acid Carbon and Oxygen. Sulplnu-ic Acid Sulphur and Oxygen. Acid Oxides. -} Phosphoric Acid Phosphorus and Oxygen. Nitric Acid Nitrogen and Oxygen. Silica Silicon and Oxygen. Water Hydrogen and Oxygen, Ammonia Nitrogen and Hydrogen. Potash Potassium and Oxygen. Soda Sodium and Oxygen. Bases -j Lime Calcium and Oxygen, Magnesia Magnesium and Oxygen. Alumina Aluminium and Oxygen. Iron Oxide Iron and Oxygen. 84 ELEMENTS OF An acid joined with n base forms a salt. For example, carbonic acid uilh the base, lime, forms the gait carbonate of lime; so, nitric acid combines with the potash to form nitrate of potash, commonly known as saltpetre, and so on. Wo will now take into consideration the most impor- tant salts of interest to tlio agriculturist; The chief of these are the carbonate of potash, forming the greater part of the ashes of burnt wood; the chloride of potash, which is the principal sub- stance in the manure called kainit; and nitrate of potash. Carbonate of soda occurs in the ash of many plants, and nitrate of soda is Chili saltpetre, often used for manure. The commonest soda salt is the chloride of sodium, or common salt. Unlike most salts, this is formed by the direct union of chlorine and sodium. When the carbonate of lime is roasted in a kiln, the carbonic acid is driven away, and lime only is left, which is called quick-lime; it is then very jwrous, and has a metallic ring. When water is poured on it a chemical action takes place by its combining with the lime; it then produces great heat, and forms the hydrate of lime, or slaked lime; but if it is left exposed to the air, the carbonic acid, which was driven from it, seeks to reunite, and brings it back to its original condition. Masons are Avell aware of this fact, us wlicn they slake the quick-lime they immediately cover it with sand to keep it from the air, or rather the car- bonic acid in the air. Another useful salt of lime is gypsum, which is a sulphate of lime. But the most important of all the salts is the phosphate of lime, because of its enter- ing so largely into the economy of both animal and vegetable life. SCIENTIFIC AND PEACTICAL AGKICULTUllE. 85 The silicates form iiu important class of salts, as it is principally by their aid that the crops are supplied with silica, as well as with the base with which the silica is combined. Thus the silicate of potash supplies both silica and potash; silicate of lime, both silica and lime, and so on. You may refer to what is said about the double silicates in a former chapter. CHAPTER XXXIX. THE ATMOSPHEEE. The atmosphere is so important to the growth of plants that it is necessary we should have a distinct knowledge of its nature and composition. The great bulk of the air consists of oxygen and nitro- gen, in the proportion of one of the former to four of the latter, only mixed, not chemically united. To give you a clear idea of what we mean by mixed, but not chemically united, let us take some lard and put a little water into it; we can so thoroughly mix them that it will be difficult to detect the water, but still the two substances are only mixed ; we will now put some potash into the mixture, and they become immediately united chemically. Of those two gases it is only the oxygen which is active, entering plants by their roots, and it is also combined with many other substances in the air and in the soil, where, you will remember, it is to be freely admitted, by means of deep plowing and drainage, to give it the opportunity of rendering poisonous matters nutritious by its action. It is found by careful inves- tigation, as we have before stated, that free nitrogen does not enter the plant at all ; and as nitrogen is 86 ELEMEl^TS OF one of the necessary organic elements, the plant must obtain it in some otlicr way. The nitrogen in the air acts only as a regulator to the oxygen, preventing its too violent action. Besides the oxygen unci nitrogen, the air has always mixed Avitli it four substances, which are good friends of the farmer. These are watery vapor, nitric acid, carbonic acid, and ammonia. Although these exist in the air in very small quantities in proportion to tho general bulk, yet if wo take into consideration the vast extent of the atmosphere, we shall discover that there is really a large supply of these substances. The carbonic acid in the air is the great supply of carbon to the crops. The nitric acid and ammonia are washed down into the soil by the rain, and, as they are very soluble, they become at once suitable for the nourishment of the plant. The power of the soil to absorb ammonia (nitrogen and hydrogen) is not confined to periods of rain, is not even confined to the periodical recurrence of dews; so often as the air is charged with carbonate of ammonia, and comes in contact with a surfoce of soil, so often will this soil be enriched by ammonia to the extent to which the aii' contains it. For this reason the soil should be open, loose, and porous, so as to make it accessible to the feriform fertilizers. This explains why cultivating frequently between root and corn crops is so beneficial. It has been estimated that an acre of land receives in these ways every year about eighteen or nineteen pounds of nitrogen. The other ingredient found in the atmosphere is watery vapor. This is simply water in the form of an invisible steam or gas. It is of use to the crops when it descends in the form of rain or dew. BCIENTIFIC AIS'D mACTICAL AGKICULTURE. 87 CHAPTER XL. THE DISSOLUTION OF PLANTS AND ANIMALS. When a plant or animal dies, tlie softer parts soon decay and separate into simpler chemical forms. • This dissolution is caused by the growth of tiny Hying things, the germs of which are always floating in the air, except in keen frosty weather, which, with the aid of oxygen, break wp the organic substances (which, we before learned, consist of oxygen, hydrogen, nitrogen, and carbon,) into the simpler substances, water, car- bonic acid, and ammonia, each of which is only a binary-element compound. If the animal or plant decays in the air, these gases escape or fly away in the air, causing an ofiensive smell ; but if the decay takes place in the ground, the soil has the power of absorbing these gases. Clay soil has the greatest power of absorption, especially that portion of it which has taken the form of double silicates. On account of this peculiar property, dry pulverized clay is one of the very best disinfectants, and makes an excellent dressing for "angry" wounds, because of its jDOAver to absorb the corrupting matter, and render the sores calm and clean. The mineral or inorganic substances likewise fall to pieces in the soil, where they remain as carbonates, phosphates, and sulphates, ready to supply inorganic food to succeeding generations. Thus you will perceive the unceasing round of change going on in the air, in the soil, in plants, and in animals, which the intelligent cultivator will wisely consider and utilize whenever possible. 88 ELEMENTS Of In soil Avliore there is a good portion of liunius, it iibounds with life. Many living creatures can be seen ■with the naked eye, but many more are revealed by the aid of tlie microscope. Crubs of insects feed upon roots of vegetables left in the soil, and they change their food into ammonia, and carbonic acid, and "water, ■which is taken up by the soil. Some grubs, however, attack gro^wing crops, and are, consequently, hurtful to them; but most of tlio grubs do more good tlian harm. Gro-wing plants "which produce real flowerS and seeds, cannot feed upon decaying matter directly; it must be changed into carbonic acid, nitrates, and ammonia before they will accept it as food. There is, however, a set of plants called fungi, but which are sporatic, belonging to the mushroom or toad-stool family, which possess the power of feeding upon vegetable matter directly, like animals. They exist in the soil, and are friendly helpers in preparing food for the higher classes of plants. In the days of witches, "fairy rings," which abound in old pastures, were an object of superstitious awe, and were long a puzzle to scientists; but the mystery was at length solved; they were found to be caused by fungi, which, commencing to grow in one spot, converted the humus into nitrates, causing the grass to grow in that spot a dark green tuft. The fungi spread out from that centre, continuing their work in a circle, thus feeding a small ring of grass, which grows greener than the rest; and so tlie "fairy rings" extend, growing larger and larger. For the best conditions of forwarding these chemical changes in the soil, so that the farmer may be benefited by them, four things are absolutely necessary: (1) The presence of oxygen. Here v.'e see the reason for deep cultivation and drainage, (stagnant water will never do), SCIEKTIFIC AND PRACTICAL AGRICULTURE. 89 by wliicli the air, with its oxygen, can enter. (2) Mois- ture in moderate quantity must be present, such as is obtained by capillary attraction, as in a flower-pot. (3) Warmth, for the purpose of oxidation, wliicli is more active in summer than in winter. (4) The pres- ence of some base in the soil to unite with the oxygen to form nitrates. The best substance for this purpose is the carbonate of lime; the base, lime, unites with the nitrogen to form nitrates of lime. The lime is next dis- carded, and potash preferred, which then forms nitrate of potash, which, you remember, is very useful for the growth of tlie crops. CHAPTER XLI. THE CAUSES AXD REMEDIES OF EXHAUSTION OF THE SOIL. In this elementary work we first considered the structure of the plant, and the manner in which it takes its food; we next took up the formation of the soil, and saw from Avhence it came; also its physical and chemical composition, from which much of the plant food is derived; next the best methods of cultivating that soil, so as to get the food ready for the use of the crops in sufficient quantity to sustain them to their full maturity; and next tlie chemical properties of substances. AVe are now prepared to consider the exhaustion of the soil, and the best remedies for that exhaustion. When 51 soil has been cropped until one of tlie sub- stances of plant-food has been used up, so that it con- tains no more in a condition to be acceptable to the plant, we say the land is exhausted. S6 ELEMENTS OF AVe have already seen that the whole of the plant food in the soil is never in a condition to he acceptahlc to vegetation. The soluble parts only are suitable for plant food, and that portion only forms a very small part of the soil. The rest of the soil may contain a large quantity of these substances, but they are held in reserve, to be called into active duty, by the action of the oxygen and carbonic acid of the air. The awakening takes time; therefore the necessity and advantage of turning over the soil as much as possible, and as long a time as possible, before the crops require the food, so as to give the air time and opportunity to act upon the dormant portion to make it soluble, and consequently available for the plants. Should it happen that this opportunity is not allowed, or perhaps neg- lected, it may occur that one crop will use up nearly all the active matter of one particular kind, so that the next crop can only get a jiartial supply — that crop will suffer because the land is exhausted. You must note, how- ever, that an exhausted soil may be quite a good one, if it only has the opportunity to recover itself, and also given time to change its sleeping matter into an active condition by the friendly helpers in the air. Some soils, however, are so deficient in some of the elements of plant food, that even if all the food in them was brought into an active condition, it would last but a short time, and the land would then be thoroughly exhausted, and could again be rendered fertile only by a supply of the substances it had lost. In some portions of the Southern States the soil has been so long cultivated with one or two kinds of crops — as much as possible of cotton or tobacco being taken, and little or nothing put in — that large tracts of land have been exhausted and abandoned. SCIENTIFIC ANt) PRA(3TICAL AGEICULTURE. 91 So, also, in tlie Northern States, immense crops of corn, wheat, and oats were grown by the first settlers, year after year, until the land wonld no longer produce these crops in paying quantities. These settlers moved farther West, and cultivated new soil, which in time became exhausted, and was abandoned in its turn. But this is very wasteful, and cannot long continue. Before we go on to state how fertility can be restored to the exhausted soil, we must inquire what sub- stances, and how much of each, have been taken from the land by the crops which have been grown upon it. CHAPTER XLIL SUBSTANCES USED BY VEGETATION. We learned in a former chapter, that the organic substances were those forming the softer parts, and the inorganic substances were those contained in the ashes left behind when the plant was burned. You had better now refer to them and commit them to memory. It has been found by careful experiment, that of the inorganic substances named there, that some are not absolutely needed for every kind of plant; yet they are always found in plants when grown in a natural way. It IS, therefore, safe to say, that they are beneficial to their healthy and complete growth. In the forest planted by nature there is no exhaustion ; neither is there any exhaustion in an uncultivated prairie; for as the trees and plants decay, their branches and leaves go back to the soil, and return to it the same substances taken from it by their growth, in addi- tion to the carbonic acid and ammonia which they had collected from the atmosphere. The long roots bring 92 ELEMENTS OF up nourishment also from the subsoil, which they leave in the form of decaying matter, or humus, on the surface soil, and must, for this reason, become richer for their growth. Even if a large portion of the growth is eaten by Avild animals, it is only laid up for a time in their bodies, to be given up again to the earth when they die. But it is a very different case when w^ grow great quantities of corn, wheat, cotton, or tobacco, and carry it away for human use. In this case the inorganic matters are carried away entirely from the land from which it was derived. Even should it be a grass field, in which cattle or sheep have been turned to graze, though they give back some of the mineral matters in their droppings to the soil, yet their bodies, which have been built up by the grass they have eaten, are .at last taken away to be consumed elsewhere. You can easily understand now, that if crops are constantly drawn from the soil, to be used by men and animals elsewhere, the materials of plant growth will be carried away little by little, until one or more of them, which is especially wanted by the crop> gives out, and the soil is thus exhausted. It is the ingredient which is least abundant that determines the fertility of the soil, as before remarked; it is the weak link in a chain that determines its entire strength. Exhaustion may be delayed for a long time by returning to the soil as great a quantity as possible of the plants grown upon it. To sell milk, cheese, beef, straw, or hay from the laud will surely impoverish it, because of the mineral ingredients they contain, as may bo determined by the amount of residue shown when they arc burned; but if yon sell butter or fat, and keep all the rest on the farm, your land Avill get better; because if you burn butter or fat, yon feCIEHTIFrd AND PKACTICAL AGEICULTtJKE. 93 will find no'resiclue; from which fact we ascertain that their constituents came from the air, and not from the soil. CHAPTER XLIII. SUBSTANCES EXTRACTED FROM THE SOIL BY DIFFEEENT CROPS. The substances taken from the soil differ greatly in quantity. One kind of crop takes proportionately a great deal of potash, as turnips; another very much lime, as clover; a third, much silica, as wheat. Each crop has its own pattern, so to speak, which requires a special set of substances to complete its construction. To enable you to have a clear conception of the ingredients, and the quantities of each kind required, we shall give you a table, prepared by several eminent chemists, which will be quite instructive upon this important topic: IXORGAXIC MATTER TAKEN FROM AN ACRE OP LAND BY A CROP OP GRAIN, ROOTS, AND CLOVER. WHEAT. Straw. Tuhnips. Clover Hay. 25 Bushels 3,000 Lbs. 20 Tons 6 Tons 2 Tons. Grain. Bulbs. Tops. Lbs. Lbs. Lbs. Lbs. Lbs. Potash 7.49 18.21 125.73 75.95 52. Sotla 97 .90 22.98 16.23 7. Magnesia 3.07 4.11 12.27 9.27 35. Lime 85 9.34 37.87 69.81 111. Phosphoric Acid. 11.87 8.15 31.11 27.87 20. Sulphuric Acid.. .08 5.82 42.26 86.56 13. Silica 84 101.82 11.64 2.58 10. Peroxide of Iron. .20 1.23 3.71 2.58 3. Common Salt 03 .33 28.69 88.15 8. Carbonic Acid 21.71 21. Total 25. 150. 340, 300. 359. 94 ELEMENTS OF If a crop is larger or smaller, tlie number of poiiiKls will vary in proportion to the quantity protluced. This table, however, gives us a very good idea of the quanti- ties of tlie different materials which are drawn from the soil. Wc see that turnips require much more inorganic matter than clover, and that clover requires more than wheat; we see, also, that all the different kinds of crops require nearly an equal share of phos- phoric acid. The other cereals, such as oats, rye, and corn, resem- ble A\ lieat closely in requiring nearly similar quantities of inorganic substances. All the leguminous or pod-bearing plants, such as beans, peas, and vetches, resemble clover, in requiring a large proportion of lime and magnesia. The analysis of turnips may also be taken to repre- sent the root crops, including mangels and potatoes, although these belong to a different order of plants. CHAPTER XLIV. EEMEDIES FOR EXHAUSTION, We have now seen that each kind of crop draws upon the soil for its own particular kinds of food, and in different quantities. It will be evident, then, that if wc grow the same kind of crop in succession for a number of years in the same soil, some of its soluble substances will ultimately become scarce, and the land becomes exhausted. But besides the mineral mat- ters, plants also depend upon the soil for a good deal of their nitrogen. This very important element is carried down into tlie soil by the rain in the form of ammonia and nitric acid; but a store of nitrogen is in SOIEN'TIFIC AND PRACTICAL AGRICULTURE. 95 all fertile soils, contained in the dead roots of former plants, and in the decaying vegetable matter, or liumus, which gives the dark color to the soil. The nitrogenons portion of the hnmus, like the inorganic matters, are liable to be exhausted by the continual cropping of the same kind of plants on the soil. We have now come to the very important subjects: The remedies for the exhaustion of the soil, and how to prevent it. There are three ways by which these ends can be attained: (1) By giving the land rest. (2) By a change of crops. (3) By the use of manures. Fallow is a very old Saxon word, whose prime meaning is pale yellow or reddish yellow, and is applied to lands plowed, not for the purpose of raising a crop, but preventing the growth of any plants what- ever, thus keeping the color of the field a pale or reddish yellow, and not green with crops. The land is then said to rest. The atmosphere during this rest has time to act upon the soil, if we let it; the rain, and snow, and frosts of winter break down and crumble the hard particles of soil, which affords the oxygen and carbonic acid an opportunity to work upon the dormant matters, and bring them into an active or soluble state, and a ncAV supply of potash and other food will be got ready for the crop when the time of rest is over. It is very important that the soil be kept open during the period of rest; for this purpose it should be occasionally plowed, harroAved, and Avorked over by the cultivator to keep open the soil to the air and to pre- vent the growth of weeds, which are sure to spring up from seeds already in the soil, or carried there by the wind. These weeds would feed upon the prepared food, and would produce large quantities of seed, which 96 ELEMENTS OF would give the former no end of trouble for years. For falloAV, then, to do its very best, the land must bo kept, as its name indicates, reddish yellow, and not green with plants of any kind. An agricultural chemist found that after a crop of beans there was in the soil 19 J pounds of nitrogen per acre; but after the same field had been fallow, the next year it contained 48 J pounds per acre. Another field, which had been sown v/itli wheat, without manure, contained, when the wheat had been removed, 2 J pounds of nitrogen per acre; after a year's bare fallow, it con- tained 33 J pounds to the acre. The great danger to a bare fallow, especially on light soils, is that these nitrates and other soluble food would be washed away, the sandy soil not having the double silicates to take up and hold in store the soluble plant food. The great danger to prairie and timber lands is the washing away of the surface soil into the rivers and creeks. Although the double silicates abound in these soils, yet, by the nearly impervious condition of the subsoil, the water is compelled to flow away from the surface, and carries with it the silicates and the fertilizing substances they contain, thus rendering the land unproductive. Drainage, to aerate, and allow the water to percolate through the soil and pass the fertil- izing matters over to the safe keeping of the silicates till needed by the plant, will give a high per cent, of profit to the farmer for his outlay. In order to reduce the dangers to light soils of a bare fallow to a mini- mum, fallow crops are grown, which take up this soluble food and make it into green fodder or roots, which are plowed in or eaten on the land. SCIENTIFIC AND PRACTICAL AGBICULTUEE. 97 CHAPTER XLV. FALLOW CROPS. The practice of giving the land rest is very old. We find the giving of the land rest enforced hy the laAV of Moses, which requires the land to rest every seventh year. Crops which are grown in rows wide apart, to permit the use of the one-horse plow, cultivator, and horse-hoe between the rows, are called fallow crops, because a great portion of the surface can be stirred and culti- vated, and cleared of weeds, and exposed to the atmos- phere almost as well as if no crop was grown upon it, and, at the same time, the soil is being profitably utilized by the growth of a supply of food, making a paying return. The United States has so many different kinds of soils and climates within its borders, that it is next to impossible to enumerate all the crops that may be useful as fallow crops. We shall attempt, however, to give a few which have come under our own observation. In the New England States, the Northern and North- western States, the principal fallow crops may be tur- nips, mangel-wurzel, or beets, potatoes, and corn. The farmer must be governed by the nature of the soil and climate which lie may use. The roots of these crops bring up plant food from the subsoil, o# their broad leaves gather in great stores of food from the air, and thus fresh humus is formed, containing nitrogenous matter, which is left in the ground for the next crop. In the Central States, including Southern Illinois, the 98 ELEMENTS OF castor bean and corn make good fallow crops. The castor bean probably surpasses all others for this climate; it is a rank-growing, deep-rooted, and broad- leaved plant, and three-fourths of what is sold of this crop from the farm is oil, whose substances came from the air, and not from the soil. The land, by this crop, is enriched and left in prime condition for the profit- able growth of wheat or any of the cereals. For the Southern States cotton plants make a good fallow crop, and will not impoverish the land under a good system of cultivation. The cotton fiber, when burned, leaves proportionately a small residue, and the oil contained in the seed did not come from the land; therefore the soil will remain fertile if the cotton-seed cake is returned to it. The washing away of the surface soil from fallows, whether bare or cropped, may be set down as the prime cause of the farmer's diffi- culty in maintaining his land in a profitably fertile condition. Drainage, assisted by deep cultiva- tion, will reduce the difficulty to the minimum. CHAPTER XLVI. ROTATION OF CROPS. We shall now consider the second Avay to prevent exhaustion of the soil. Farmers generally feel that they cannot let the land rest more than is absolutely necessary; therefore, instead of having the land fiillow, they make a Set of changes of crops, called a rotation, or round. You have learned that the different kinds of plants grown for a crop use the same substances, but they show a great variation in the quantity required by SCIENTIFIC AND PEACTICAL AGRICULTUKE. 99 each; therefore, if one kind of crop be grown on the same field for successive years, it is likely to use np one or more of the particular substances needed; the supply will, in consequence, become inadequate, and the crop then shows it by becoming yellowish, weak, and sickly. But if a different kind of crop be grown on the land, it may not require so much of that kind of food as the for- mer crop did, but draws a different set of substances, and thus gives time for the others to accumulate in the soil in a soluble condition, until the first crop comes round again, when it will find a supply of its food ready for its use. But a good farmer does not wait till his land becomes sick of a crop before he changes it; he gives a regular round, or succession, of crops to prevent this. The principle to be kept in view, in fixing on a rota- tion of crops, should be the succession which is best suited to draw from the soil the largest net return, while the capabilities of the land are at the same time maintained and increased. There is a rotation common in England called the Norfolk course, from which we may get some instruc- tion by investigating the reasons for its being a general favorite in many localities: First year Turnips. Second year Barley. Third year ..,...., Clover. Fourth year Wheat. Let us examine this course by the table given in a former chapter. Turnips take out of the soil large quantities of potash, soda, phosphoric acid, sulphuric acid, and chlorine. The second, barley is sown, which requires much less potash, soda, sulphuric acid, etc., but requires much more silica. The third year comes the clover, requiring a moderate amount of potash and sulphuric acid, very little silica and soda, but a large 100 ELEMENTS OF supply of lime and magnesia. In the fonrtli year comes "wheat, requiring a large amount of silica, but a small portion of the other substances. By this time the soil has been able to recover itself; the potash and other substances required in large quantities by turnips have been rendered soluble, and have accumulated, and the land is again in order to begin the course anew. The rotation practiced by many intelligent farmers in the United States is: First year, clover; second year, wheat; third year, corn; and fourth year, oats; then comes clover again. The practical considerations in favor of a rotation of crops are the cleanliness of the land; the con- tinuous supply of food; the distribution of labor throughout the several seasons of the year; and the consolation, if one kind of crop fails, the farmer will not be in the "slough of despond." The adaptation of our farm products to the general wants of the people, as well as the varying climatic conditions, argue also in favor of a variety of crops. The alterna- tion of green crops and root crops with cereal crops may bo set down as an axiom of good and im- proved agriculture. CHAPTER XLVIL MANURES — THE GREAT REMEDY FOR EXSAUSTIQ]!?. We have now come to the great remedy for the exhaustion of the soil, brought about by any cause; it is the use of manure. The term tnanure, iii Its modern meaning, includes every substance^ whether of vegetable, animal, or min- eral origin^ Wliich, when applied to tiie soil, has the SCIEKTIFIC AND PRACTICAL AGRICULTURE. 101 effect of increasing its fertility. Its ancient meaning was: Worked over by hand. In this sense it was applied to the manual labor which made tlie land fertile. Shakespeare uses it with this meaning in "Othello" by the month of "lago," when speaking of a garden. He says: "Either to have it sterile with idle- ness, or manured with industry." There are three principal modes in which ma- nures act upon the soil so as to enable it to grow more and better plants. (1) They supply deficiencies in the soil, by giving to it substances which Avere wanting. (2) They act mechanically on the soil, by render- ing clay lands lighter and more open; or supplying sandy soils with humus, by giving it a closer body, thus enabling it to hold plant food, and encouraging capillary attraction. (3) Some act as a stimulant. They do this by causing the soil to give up for immediate use the reserve store of plant food, instead of adding more. They drive the soil to do more work in a given time, as a horse is driven by the spur. Some kinds of manures serve all three purposes; some two of the three, and others only one. The various manures used at the present day may be considered as belonging to the following classes : 1. Green manures. 3. Farm-yard manures. 3. Calcareous manui'es 4. Artificial manures. The term green manure is applied to the system of growing a crop for the purpose of plowing it into the land. If a crop grown upon a field is returned to it, it looks like giving back to the land that which was only its own; but the advantage gained becomes palpable 102 ELEMENTS OF wlien "\vc consider how much deeper the roots of hardy plants go down for their food than those of the more delicate kinds cultivated for a crop. Thus the plant food is brouglit where it can be used, Avhich was before beyond its reach. Two very opposite classes of soil arc benefited by this system. If a hardy crop, such as buckwheat, is sown upon a thin soil, and turned in just at the time it begins to flower, a large increase of organic matter is thus added to the soil. The advantages are very soon apparent; for the soil is enabled to hold larger supplies of moisture, and can take in more gaseous matter from the atmosi^here. The growth of clover is one of the most general means of improving tlie soil. It matters not whether it be on light lands, or heavy, or lands of the intermediate classes; in each case we see the fertil- izing powers of all these soils being improved and increased. The clover crop is, in some respects, an exceptional one, because it is allowed to stand for a longer period before being plowed in. In the meantime, it is not only making growtli above ground, but also deep into the subsoil. We must not forget the fact that tlie groAvth beneath the surface is pro- portioned to the growth above the surface; therefore, if the growth above the surface is eaten down, the extension of the root suffers in proportion. BCIEJSTTIFIC AND PEACTICAL AGEICULTUEE. 103 CHAPTER XLVIII. CO]SrCER]S'^ING FARM-YAED MAISTUEE. Farm-yard manure has long been acknowledged as the best manure used on the land. The manure produced by different animals is not of the same quality; its value is also aflfected by the food the animal receives. From full-grown animals the manure is rich in nitrogen and phosphates. From young animals and cows giving milk it is much poorer, because much of the food goes to build up the bones and flesh. The milk also contains nitrogenous matter and mineral sbbstances; the manure, therefore, is poor in these sub- stances. The quality of manure, as we just now said, is greatly aflfected by the kinds of food the animals receive; thus, animals which receive a ration of oil- cake will produce very much better manure than those fed upon straw, grass, or hay, because the oil- cake contains a large amount of nitrogen, phos- phoric acid, and potash. Farmers, on this account, often find it profitable to buy oil-cake to feed to their animals, the manure being then richer and more valu- able to the land. A ton of farm-yard manure contains about one thou- sand, five hundred pounds of vrater, about four hundred and fifty pounds of solid matter, and about fifty pounds of soluble fertilizing substances, mainly ammonia, silica, phosphate of lime, lime, magnesia, potash, soda, common salt, sulphuric acid, and carbonic acid. We have here, then, all the substances required by plants. 10-i ELEMENTS OF You "will notice the large quantity of water and insoluble matter in farm-yard manure, and will be inclined to think that it is both unprofitable and laborious to haul two thousand pounds to supply only fifty pounds of fertilizing matter. Yet, for all that, the intelligent farmer finds it to be one of the most economical and useful manures that can be used. Its bulk is useful to most soils; for it acts physically by binding light loose soils, and upon heavy soils by sepa- rating them and making channels for air and water to penetrate. Upon either light or heavy soils it is also very valuable, because of the carbonic acid generated by the decay of the vegetable substances it contains, which acts upon the dormant matter already in the soil, and changes it into soluble plant food. Its great value consists in the fact that it returns to the soil the very substances which were taken from it by the plants; therefore it pays back to the soil part of the loan made by it. Any farmer who neglects his farm-yard manure, thinking to make up the loss by artificial manures, Avill find himself most egregiously in error, and will be ready to join in the exclamation: ''He that trusts to artificial manures, expecting them to supply all the requirements of the soil, will find such trust a delusion and a snare!" CHAPTER XLIX. JIOW TO INCPvEASE THE FEETILIZIXG POWEES OF MANUEE. The superior quality and value of the manure of animals fed upon rich foods, such as oil cakes, as a means of producing meat, has been fully tested. The SCIENTIFIC AND I'RACTICAL AGEICULTURE. l05 investigation of this subject by Lawes and Gilbert, of England, places facts before us of immense value. It is sliown by the scientific inquiry of these gentlemen that it is possible to obtain from a ton of each of the following named foods a manure enriched with fertil- izing substances valued as follows: BASE OF VALUES. If one ton (2,240 lbs.) of pure guano be worth $G0 00 Then manure from 1 ton decorticated cotton-seed cake is worth 32 50 Then manure from 1 ton rape cake is worth 24 50 " " 1 " linseed cake is worth 23 12 " " " 1 " undecorticated cotton-seed cake is worth 18 75 Then manure from 1 ton bran is worth , 13 50 " " " 1 " clover hay is worth 1150 " " " 1 " oatsisworth 8 75 " " " 1 " wheat is worth 8 25 " " " 1 " corn meal is worth 8 00 " " " 1 " meadow hay is worth 7 00 " " " 1 " oat straw is worth , 3 50 " 1 " wheat straw is worth 3 00 " " " 1 " potatoes is worth 175 These results represent a great amount of labor and skill, and give information of real value to farmers in any country. When farm-yard manure is placed in a heap it fer- ments. This fermentation is caused by the growth of immense numbers of tiny plants of the nature of fungi, the same as those found in fermenting wine or cider. These spores, or seeds of these plants, are always floating about in the air, and attaching themselves to any dead animal or vegetable matter, where they find the food they require, and begin to grow and multiply with great rapidity. As they feed upon the organic matter of the farm-yard manure, they break it up into water, car- 106 ELEMENTS OE' bonic acid, ammonia, and other organic acids, by the aid of the oxygen of the air. A great deal of heat is then produced; and if the manure is kept moist, and not allowed to get too hot, the organic acids combine with the ammonia and hold it; but if it gets dry and too hot, the carbonic acid is formed too rapidly, and combines with the ammonia, forming carbonate of ammonia, which is very vola- tile, and flies off in the air. On the other hand, if it gets too wet, the water filters through, and the organic acids and ammonia flow away into the streams. An intelligent farmer Avill study to avoid these losses. A strong pungent smell gives him notice of the waste of ammonia in the air, and black streams from the heap give him warning of the waste of organic acids and ammonia running away to a lower level. To cure the first, he should moisten the heap with its own drainage; to prevent the second, he should try to keep it drier by sheltering it from the rains, or he may collect the black drainage into a tank and use it on the land. A thrifty farmer will be as careful about the shelter of manure as of any animal or implement on the farm ; lie Avill also see to it that the heap rests on a floor that is impervious to water. Without this, the shed will be worse than useless, because the urine will be lost by soaking away; the manure, in consequence, heats, and its virtues fly away. Ammonia is a coy fairy, and is easily caused to vanish in the air. SCIEifTIFIC AND PRACTICAL AGllICULTUKE. 107 CHAPTER L. EXPERIMENTS WITH FARM-YARD MANURE. We wisli to impress upon your minds tlio great superiority of manure stored up in covered sheds, with tight floors, over manure kept under the ordi- nary conditions. The following experiments will tend to convince the most skeptic upon this subject. Lord Kinnaird, a Scotch land owner and farmer, in order to test the merits of manures kept in these two ways, measured off four acres of good soil; two of them were manured with tlie ordinary kind, and the other tv/o Avith an equal quantity from a covered shed. The whole was planted in potatoes, with the following results : RESULTS FROM THE ORDINARY FARM-YARD MANURE. First acre 273 bushels. Second acre 293 " Total. 564 RESULTS FROM THE COVERED MANURE. First acre 443 bushels. Second acre 471 " Total 913 '« The difference in favor of the two acres supplied with the covered manure is three hundred and forty- nine bushels; but the advantage does not end here. The same land was next sown in wheat, and produced as follows: WHERE THE ORDINARY MANURE WAS USED. WHERE THE COVERED WAS USED. MANURE First acre 41 bushels. Second acre 43 " Total 83 First acre... 55 bush. Second acre 58 " Total 113 *•• /Gl Ihs. per\ I bu h. ; 108 ELEMENTS OF The diJQference again in favor of the land which was fertilized with the covered manure was thirty bnshels. The yield of straw was also one-third more upon the land to which the covered manure was applied than on that where the ordinary farm-yard manure Avas used. Upon light lands, which have little power of retaining the soluble matter contained in the manure, a great difficulty has been long felt; but very good results have been attained by applying well-rotted manure to the land while it was carrying a crop capable of rapid growth, it being able to use the solu- ble portions of the manure quickly. The clover crop has been preferred for this purpose, to which the manure is applied at various periods of its growth. The results secured were the changing of the farm-yard manure into a living crop, and afterwai'd making that crop yield plant food to the soil by plow- ing it in, which, by its slow and steady decay, gives nutriment to the wheat plant progressively. The wheat is then as fully benefited as if the soil had acted as the guardian of the store of plant food. On light soils, then, manure should be applied in a Avell broken down condition at the time the plant needs it — that is, in the spring — or applied to a vigorous kind of plant while it is in active growth. CHAPTER LI. COMPOST HEArS AND THOUVENAL S PROCESS OF PRO- DUCING NITRATE OF POTASH. Compost heaps are the means of making a very valuable manure for applying to the surface of the soil. They are composed of vegetables of various kinds mixed with earth and quicklime, with or Avithout SCIENTIFIC AND PIUCTICAL AGRICULTURE. 109 salt; and, if- properly and carefully made, will produce a good supply of the nitrat3 of potash. This sub- stance is not purchased for use as an artificial manure, because its employment for the manufiicture of gun- powder gives it a very high value. "Wood ashes contain a considerable quantity of potash. The means of producing artificially a cheap supply of the nitrate of potash was discovered in France by Monsieur Thouvenal in 177G. At that time there was a great desire in that country to get a supply of this substance independent of any foreign country, and the result was that enormous quantities were produced by Thouvenal's method. It may not be uninteresting to state here that Thomas Harris, in England, was granted a patent in 1741 for the production of saltpetre, or nitre, upon a plan similar to that of the Frenchman, for which he received a prize. And as early as 1630, David Eamsay, of Scotland, procured a patent " to mul- tiplie and make saltpetre in an open fielde in fower acres of ground, sufficient to serve all our dominions." The art of war stimulated the inventors— not the arts of peace. The principle upon which these nitre beds were formed is a matter of interest to the cultivator of the soil, because, by his practice, he has been producing nitrate of potash without knowing it, or the cause of a success which results so satisfactorily to him. The nitre beds are simply compost heaps, formed as follows : Good earth is enriched by the addition of sheep manure, liquid manure, and quicklime ; the heap should be occasionally turned over; the nitrate of potash is formed within the heap, and is easily separated after- wards by washing the earth, and then evaporating the water. 110 ELEMENTS OF The changes which take place are these: Tlie nitro- genous matters in the manure decompose so as to form ntiric acid ; Avliilst the lime releases the potasli from its combination in the soil; and, by the union of the nitric acid and potash so produced, we have the valuable fertilizer, nitrate of potash. The system of plowing farm-yard manure into the soil, and then ecattering lime on the surface, and harrowing it in, thus mixing the earth and quicklime, which finally mixes Avith the manure, brings about the condi- tion favorable for the formation of the nitrate of potash. If the lime and manure should mix on the surface, much ammonia would be formed and escape in the air. Success in a certain mode of culture has directed many a farmer into a system which gives good returns, even when the why and wherefore is yet unknown to him. CHA PTER LII. THE USES OF CALCAREOUS MANURES. Lime, chalk, marl, and gypsum are all classed as calcareous manures. They act in three diflercnt ways: (1) They supply plant food themselves. (2) They set free other substances in the soil, thus fitting them for plant food. (3) They act mechanically upon the soil. Marly or calcareous soils would not be benefited by the addition of more lime; but clay soils, with a good supply of humus, are much improved by an occasional dressing — say once in five years. Lime and chalk, as we find them, are united with carbonic acid gas. There seems to be a strong affinity between them; they are, therefore, very difficult to SCIENTIFIC AND PRACTICAL AGRICULTURE. Ill separate, and it can only be done by submitting them to a strong heat. When they have been separated by driving away the carbonic acid gas into the air witli tlie heat, they lose no opportunity of uniting again. This fact enables us to understand more clearly much that is peculiar to lime. The farmer is a great loser if he is careless in protecting his quicklime from the air, just the same as a builder would be who neglected to cover his slacked lime to be used for mortar; his loss Avould be discoverable to the eye, because it would have lost its power to make a good bond — that is, to crystallize — and would crumble out of the joints; but the farmer's lime, going into the land, he cannot so easily discover the loss, and he supposes something else is in fault. Intelligent farmers know the value of quicklime, and carefully avoid such waste. All plants require lime in their food. Turnips and clover need a very large supply. A crop of two tons of clover uses one hundred and eleven pounds of lime, as will be seen by referring to the table given in a former chapter. The best form of lime intended for plant food is the carbonate. In the case of meadow land it is found after a top dressing of carbonate of lime, that the sweeter and better kinds of grass will spring up where it would not grow before. By the decay of the vegetable matter, too, the inorganic substances, which formed part of the dead plant, will be set free in the condition just right to the new crop. You must bear in mind, however, that lime applied to the landjAvithout manure, will be chiefly a stimulant; hence the truth of the old adage : "Lime and lime without manure, Will make both farm and farmer poor." ll^ ELEME2^TS 01? CHAPTER LIIL SUMMARY OF THE VIRTUES OF LIME. The great value of the double silicates in the soil we noticed in a former chapter. We shall now endeavor to discover what is the first step in their formation, and how the farmer can forward the work. The application of lime in a caustic condition seems to have the power necessary to begin this chemical change; it displaces some of the alumina, or soda, if it happens to be present in combination with silica and alumina, and forms the first of the double silicates, viz. : Silicate of alumina and lime. The first step being attained by the energy of the caustic lime, the formation of the others follow in due order. The following is the analysis of limestone found on land near Cumberland, Md., belonging to the Hon. William J. Eead: Carbonate of lime 80.93 per cent. Combined silica and alumina 14.43 " Alumina and oxide of iron 3.60 " Moisture 1.04 " The constituents of this lime, it will be observed, make it very desirable as a fertilizer for either clay or sandy soils. On clay soils it encourages the formation of the double silicates, and renders the soil more open and friable, which favors the admission of air; and, on sandy soils, the alumina gives them increased plasticity, and the lime and iron promotes the cohesion of particles, which, in turn, increase the power of the SCIENTIFIC AND PRACTICAL AGRICULTURE. 113 sandy soil .to hold moisture by capillary attraction, as well as forming the double silicates. The soil is thus enabled to hold plant food and moisture to an extent it never could do before. By this treatment the hungry and the stubborn soils are, to a great extent, cured of their bad propensities. The action of lime in the soil may be summarized as follows : (A) In its caustic state, as a hydrate of lime, it works out five distinct results: (1) It acts rapidly on the organic matter in the soil by promoting decomposition, which changes nitro- genous matters into available ammonia. (2) It neutralizes deleterious organic acids in "sour" land, and improves and sweetens the quality of the herbage. (3) It favors the formation of nitrate of potash in the soil. (4) It . decomposes the silicates of the inorganic matter in the soil, setting free the alkalies (potash and soda), and thus changes dormant matters into those of an active character. (5) It promotes the formation of the double silicates. (B) When applied to the soil, in its milder form, as carbonate of lime: (1) It contributes a supply of plant food. (2) It neutralizes organic acids. (3) It exerts a beneficial influence on sandy soils, by imparting a certain amount of tenacity ; on heavy soils, by opening up and dividing it; and on peat soils, by breaking down their vegetable fibrous tissues. Marl is a mixture of carbonate of lime and clay and siliceous matters — all of which act beneficially on the soil. Marls are so variable in their composition— the lime constituent being in some only eight per cent, and 114 iELIiMENTg 01* others from eiglity to ninety per cent. — that it is yery difficult for the farmer to know their value, as he can have no certainty as to their composition. Green marl generally contains about six per cent, of lime, and thirty-two per cent, of silica. Gray marl contains about forty-two per cent, of lime and twenty per cent, of silica. Chalk marl contains about fifty per cent, of lime and about eight per cent, of silica. It is, therefore, no surprise that the experience of those using them has been very varying in results. The custom of using marls for fertilizing the soil is of great antiquity. Its utility was proven many cen- turies before the reason was known. Gypsum is a sulphate of lime, often mixed with the Carbonate in many marls and chalks. It supplies both sulphur and lime to the crops; but it has not the value of the carbonate in causing chemical changes in the soil. CHAPTER LIV. THE ARTIFICIAL MANURES — GUANO AXD BOXES. Artificial manures are substances employed to supply special wants of the plant, which may be absent or not abundant enough in the soil; and they are called artificial because the art of man is employed to import or manufacture them. Their introduction is of a comparatively recent date; but their use as special fertilizers has become very general. It seems scarcely credible that within a period of less than fifty years these manures should have been brought to the notice of farmers, and to have secured such a universal acknowledgment of merit from them in every country where farming is a business, and not SCIEKTIFIC AND PEACTICJAL AGRICULTUEE. 115 merely a perfunctory occupation. It is proof positive that these manures have met an important want, hitherto unknown. Baron Liebig, guided by a careful study of the elements of tlie food of plants, in 1840 pointed out the properties of guano as being the most infallible of all manures for supplying the cereals with food peculiarly adapted to their enrichment, and urged farmers to use it. The first introduction of guano into England was a consignment of thirty bags to a merchant in Liver- pool, in 1839; and when the Royal Agricultural Society of England held a meeting in 1841, a sample of guano was placed on exliibition as a novel Curiosity. Peruvian guano has always been accepted as tiie best; the first cargoes were exceptionally rich, and contained, on an average, seventeen per cent, of ammonia and from twenty to thirty per cent of phosphates. This manure is the excrement of sea fowls, and their bodies added, which have accumulated for centuries and remained uninjured by rains. It was found on the rocky cliffs of islands off the coast of Peru in great quantities; indeed, some of the deposits accumulated to such an extent as to become two hundred feet deep. The richest deposits were first used; that in the market now is of less strength, and consequently of less value. The influence of the first Peruvian guano upon strong clay was unequaled by any competing manure; upon light soils it did not do so well, yet it Avas found to be very valuable. Guano is adulterated by mixing it with yellow clay, gypsum, ground bones, chalk, common salt, sand, and powdered coprolites. A bushel of guano should not weigh more than fifty-six or sixty pounds, and should contain not more than two per cent, of sand and fifteen per cent, of moisture. 116 Elements of The first step towards the use of artificial manure •was the use of bones — a practice Avhich dates from the commencement of the present century. The constituents of hones differ according to the age of tlie animal — those of the young containing less earthy matter than those which are older. In full grown animals the earthy matter is about sixty-seven per cent. in thoroughly dry bone, the other thirty-three per cent, being ihe organic matter. The earthy constituents are lime, phosphorus, magnesia, and soda; tlie organic part is composed of sulphur, carbonic acid, and ammonia. The analysis of the eartliy matter in bone is: Phosphate of lime, fifty-eight; lime, four; phosphate of magnesia, two; soda and common salt, three pounds in every hundred pounds. CHAPTER LV. PHOSPHATIC MAN'tJEE. Phosphates are combinations of phosphoric acid with a base. Phosphate of lime is by far the most valuable; it forms nearly half of the substance of bono. Phosphorus itself is found in combination witli blood, flesh, milk, and brains. It has been estimated that each cow on a farm makes a demand for about eighty pounds of phosphates yearly, and thirty gallons of milk contain about one pound of the phosphate of lime. It is no wonder, then, that the use of phosphates has become an established and remunerative practice. Supcrphos])hate, or monocalcic phosphate, is too solu- ble, and apt to produce vegetation of an unhealthy character. The mixture of lime with it will remedy SCIENTIFIC AND PEACTICAL AGEICtJLTURE. ll? this injiiribiis action by bringing it back to a bicalcic, or more sloAvly soluble state. Phosphates may be nsed with advantage on light loams, well-drained lands, pastures for dairy- purposes, pastures whore young stock graze, and the forcing of the germination of seeds, when it is desiralile to pusli them past the period when insects are destructive. The demand for phosphatic manures has been so great that tlie supply of bones is inadequate ; therefore supplies from other sources had to be sought, and chemists set about the work of discovery. Sir J. B. Lawcs, of England, was the successful investigator, and m.ade the valuable discovery that phosphate of lime could be obtained from certain kinds of rocks, as well as from bones. Many doubted his ability to do so for some time; but facts are stubborn things, and, by actual demonstration, he established the truth of it beyond all cavil. It can hardly be estimated how enor- mous the advantage of this discovery is to the farmer. The new product is known as mineral superphos- phate of lime. The supply of phosphatic rocks may be had in various parts of the world, and thus causes an active competition, which keeps the price reasonable. The mineral phosphate of lime, in its crystalline form, closely resembles the beryl or emerald ; so slight is the difference, that mineralogists have been frequently deceived by it; for which reason it received the name apatite — a name derived from the Greek word apateoe: to deceive. Another supply of phosphatic manure has been recently discovered by Professor "Wrightson and Dr. Munro, of Downston College of Agriculture, in Eng- land. The basic-cinder, obtained in the depliosphoriza- tion of iron in the process of making steel, is found to 118 ELEMEisTS OF contain from fifteen to twenty per cent, of pliosplioric acid united with lime, iron, and alumina. This cinder, when finely pulverized, and liberally applied to the land, is found to he as good for the crops as the other well-tried phosphates. If a soil contains little carbonate of lime, ground bones may be used, because the carbonic acid in tlie air and soil will soon change it into the slowly soluble bicalcic state, and form at the same time a carbonate of lime. Superphosphate is an excellent manure for turnips, or other rapidly-growing crops, and acts not only as a stimulant, but also as a food. For wheat crops, and all grasses which are a long time in the ground, bone dust or bone ash is best, particularly if the ground seems deficient in phosphoric acid. The adulteration of bone manure, when the bones are in fragments of a good size, is difficult. Bone meal is commonly mixed with oyster shells, the enamel of which can be easily detected with a magnifying glass; sand, chalk, and salt, are also added to increase tlie bulk and profit, not to the farmer, but the manu- facturer. As a rule, bone manure is now professedly mixed with powdered coprolites and other phosphatic substances, thus forming valuable combinations, which are often profitably applied to the land in conjunction with £:uano. CHAPTER LVI. KITKOGENOUS AND OTHER MANURES. "\Vr shall next consider the nitrogenous manures. The two substances, ammonia and nitric acid, with other nitric compounds, Avhen applied to plants, are SCIENTIFIC AND PEACTICAL AGEICULTURE. 119 taken up in