HIGH FARMING WITHOUT MANURE. SIX 8 .Via LECTURES Otf AGRICULTURE, DELIVERED AT THE EXPERIMENTAL FARM AT VINCENNES. I M. GEORGE VILLE, PROFESSOR OF VEGETABLE PHYSIOLOGY AT THE MUSEUM OF NATURAL HISTORY, PARIS. « BOSTON : PRESS OF GEO. C. RAND & AVERY. 1866. 9 \2LmmzM Class £l_ Book .h-L J *" ♦7 HIGH FARMING WITHOUT MANURE. SIX LECTURES 0i\ AGRICULTURE, DELIVERED AT THE EXPERIMENTAL FARM AT VINCENNES. M. GEORGE VILLE, PROFESSOR OF VEGETABLE PHYSIOLOGY AT THE MUSEUM OF NATURAL HISTORY, PARIS. BOSTON : PRESS OF GEO. C. RAND & AVERY. 1866. ^ m EXCHANGE Mr3 l 06 CONTENTS. LECTURE FIRST. (5th June, 18C4.) Pagk On the Science of Vegetable Production 2 LECTURE SECOND. (12th June, 18G4.) On the Assimilation of Carbon, Hydrogen, and Oxygen by Plants 18 LECTURE THIRD. (19th June, 1864.) On the Mechanical and the Assimilable Elements of the Soil " 32 LECTURE FOURTH. (26th June, 1864.) On the Analysis of the Soil by Systematic Experiments in Cultivation 40 LECTURE FIFTH. (3d July, 1864.) On the Sources of the Agents of Vegetable Produc- tions 66 IV CONTEXTS. LECTURE SIXTH. (10th July, 1864.) Page On the Substitution of Chemical Fertilizers for Farm- Yard Manure Appendix 106 TRANSLATOR'S PREFACE. The researches of M. Ville, which are now placed at the head of the most important discover- ies science has yet made for the benefit of agricul- ture, were, like all innovations, received at first with something more than coldness and indiffer- ence. It has ever been thus : the most pregnant ideas, those destined to exercise the happiest in- fluences upon society, are always accepted with reluctance ; for they disturb preconceived no- tions, they upset so many plausible theories, and humble our conceit ; therefore they are always met with objections and opposition from your " practical men " alarmed at the scientific rigor of the formula, and from savants always disposed to oppose one theory by another. But true sci- ence ultimately makes its way, notwithstanding, by virtue of that providential power which, amid a host of obstacles and diversions, finally achieves progress. VI Many chemists, even the most illustrious, had devoted themselves to the study of the natural agents of fertility, previously to M. Ville. Their investigations led to most important results ; but in spite of the advantages they offered, they left a general impression of insufficiency, and discour- agement soon succeeded enthusiasm. Anim-il charcoal and guano, for example, gave rich har- vests, but it was soon found that they were expe- dients, and not specifics. Even farm-yard manure justified the title of perfect manure but very incompletely. It did not always respond to what was required of it, and moreover is not sufficiently abundant to restore to the soil all that is taken from it, as the residues of a harvest con- sumed at a distance cannot all be returned to the field, which, it may be said, leaves us with exhaustion in prospective. So true is this that, even where manure is col- lected with the greatest care, the necessity for supplying the evil with stimulants is still felt. Fossil manures present themselves to supply this deficiency, and they certainly possess great value, but do they unite every quality necessarv to secure us against fresh disappointment? There lies the pith of the question. When agriculturists demand an analysis to test Yll the richness of a field and repair its losses after each harvest, they lose sight of the fact, that each field has its own peculiar wants, and what will suit one may not suit another. It is by stating the problem in these terms that M. Ville has arrived at its solution. He has studied the appetites of each plant, or at least, of those three great families of plants upon which agricultural industry is mostly exercised, viz : — the cereals, leguminous plants, and roots : and he has deduced from this study the formula of a normal manure. There is nothing extravagant in stating that light has thus replaced darkness, that order has succeeded to chaos, and that the phantom of sterility is laid. If, like all mundane things, the system is perfectible, the specialization of ma- nures — or, to speak more correctly, the nutri- tion of plants — is the law which will make agri- culture pass from the condition of a conjectural to that of a positive science. To operate with greater certainty, M. Ville removed every element of error or doubt from his experiments, and proceeded by the synthetic method. He took calcined sand for his soil, and common flower-pots for his field. Ten years of assiduous observation and experiment led him to recognize that the aliment preferred by cereals is — nitrogen ; by liguminous plants — potassa ; by roots — the phosphates: we say the pre- ferred element, but not the exclusive : for these three substances, in various proportions, are necessary to each and all, and even lime, which humus renders assimilable, must be added. These facts, proved in pure sand by means of fertilizers chemically prepared, were next re- peated in the soil of a field on the Imperial farm at Yincennes, at the expense of the Emperor, who, with that sagacity and tact which marks his every public act, recognized in M. Ville, even at the time he was violently opposed and unpop- ular, the man most capable of turning the con- quests of science to the advantage of agriculture : he extended a generous and powerful hand to the professor, and the most complete success has crowned his glorious initiative. During the past four years curious visitors, drawn to the farm by the report of M. Ville's experiments, have been shown a series of square plots, manured and sown in conformity with rules laid down to test their efficacy. Upon some of these plots the seed has never been varied ; the same soil has been planted four times in suc- cession with wheat, colza, peas, and beetroot : giving them, at the commencement, a supply of the normal manure, and adding annually what M. Ville terms the dominant ingredient, that is to say, the special manure of the series. Upon the other plots, the seed alternated during the qua- ternary period at the expense of the normal ma- nure, by changing the dominant according to the nature of each plant introduced into the rota- tion : and under these conditions, the crops have reached to results of irrefutable eloquence. But as a proof necessary to satisfy prejudiced minds, side by side with the plots which had re- ceived the complete manure, others were placed in which one or more of the elements were omitted. In the latter, vegetation was languid, and almost nil, proportionally to the quantity and quality of the absent ingredients, to such a de- gree, that what was wanting could be ascertained by the decrease of vigor in the plant. A little practice thus leads to an appreciation of the qualitative richness of a soil. For the suppression of one of the principles of fertilization produces in each vegetable family differences, which indi- cate to the observer the part which each principle performs, and the proportion in which it is ab- sorbed. These experiments, the fundamental bases of theory, have not, however, the reguiat- iiig of agricultural practice for their object. M. Ville assigns four years to the action of the nor- mal manure, replenished after each harvest by the dominant element; renewing this normal manure, however, upon the first signs of a fall- ing off in the crops. By adding, according to M. Ville's system, ni- trogenous matter, phosphate of lime, and po- tassa, — that is to say, a normal or complete ma- nure to calcined sand, the seed-wheat being- equal to 1, — the crop is represented by 23. Upon withdrawing the nitrogenous matter from this mixture of the four elements, the crop fell to 8.83. Upon withdrawing the potassa, and retaining all the others, the crop only attained to the figure 6.57. When the phosphate of lime was omitted, the crop was reduced to 0.77 : vegetation ceased, and the plant died. Lastly, upon abstracting the lime, then the crop, the maximum of which was represented by 23, was only 21.62. From the above facts we draw these conclu- sions : — that if the four elements of a perfect manure, above named, act only in the capacity of regulators of cultivation, the maximum effect XI they can produce implies the presence of all four. In other words, the function of each element de- pends upon the presence of the other three. When a single one is suppressed, the mixture at once loses three-fourths of its value. It is to be remarked, that the suppression of the nitrogenous matter, which causes the yield of wheat to fall from 23 to 8.33, exercises ouly a very moderate influence upon the crop, when the plant under cultivation is leguminous. But it will be quite otherwise if, in such case, we remove the potassa. W we extend the experiment to other crops, and successively suppress from the mixture one of the four agents of production, we arrive at the knowledge of the element which is most es- sential to each particular crop, and also which is most active in comparison with the other two. For wheat, and the cereals generally, the element of fertility, par excellence, — that which exercises most influence in the mixture, — is the nitroge- nous matter. For leguminous plants, the agent whose suppression causes most damage is po- tassa, which plays the principal part in the mix- ture. For turnips and other roots, the dominant element is phosphate of lime. By employing these four well-known agents, M. Ville's system may well replace the old sys- tem of cultivation. With him, the rule that ma- nure must be produced upon its own domain is not absolute. During four succeeding years, M. Ville has cultivated, at the Vincennes farm, wheat upon wheat, peas upon peas, and beetroot upon beetroot: and he entertains no doubt that he could continue to do so for an indefinite period, the only condition necessary to be fulfilled being — to return to the soil, in sufficient proportion, the four fundamental elements above named. Suppose we wished to cultivate wheat indefi- nitely. We should at first have recourse to the complete manure, and afterwards administer only the dominant element, or nitrogenous matter, until a decrease in the successive crops showed that this culture had absorbed all the phosphate of lime and potassa. As soon as a diminution in the crops manifests itself, we must return to the complete manure, and proceed as before. Suppose that, instead of an exclusive culture, it be desired to introduce an alternate culture in a given field. We commence with the agent that has most influence on the plant with which we start. If that be a leguminous plant, we at first administer only potassa. For wheat, we should add nitrogenous matters. If we con- Xlll elude with turnips, we have recourse to phos- phate of lime ; but when we return to the point from which we started, all four elements must be employed. As may be seen, this system differs radically from that hitherto adopted. It has not for its basis a complex manure administered to the soil by wholesale, in which we endeavor to turn all its constituents to account by a succession of different crops. In M. Ville's system, he sup- plies to the soil only the four governing agents of production, which are added gradually, one after another, and in such manner as to supply each kind of crop with the agent that assures the maximum yield. The experiments at Vincennes were quite con- clusive, but M. Ville wished to verify them on a larger scale. For this purpose, land on the estate of Belle Eau, near Donzere, in Dauphiny, was placed at his disposal wherein to open a new field of experiments. The results were just the same. On the 4th of July last, an audience of two hund- red farmers, and others interested in the progress of agriculture, assembled under the lofty trees at Belle Eau, to listen to the professor's explana- tions and witness the proofs of the soundness of his new system. XIV He stated that the experimental field, divided into seven equal portions, was sown in November last with " Hallett Wheat." One portion received no manure at all ; consequently the product, both ears and straw, was weak and frail. Each of the other portions was fertilized with one of the sub- stances which constitute wheat (phosphate of lime, potassa, lime, and nitrogen). They pre- sented a series of interesting products, the last of which — that is to say, the most advantageous as to yield — was reaped from that portion of the soil fertilized with an artificial mixture of all the constituent substances united. Devoid of all scientific nomenclature, which frequently embarrasses most agriculturists, M. Ville's lucid and brilliant expose convinced the most incredulous. Almost every auditor retired with the firm resolution of repeating the pro- fessor's experiments for himself. All manure must contain principles, mixed in certain proportions, the combination of which is indispensable. In this particular, M. Ville has invented nothing, but limited himself to the spe- cializing and better defining their effects, with- out, however, forgetting those which are purely mechanical. It remains now for practical men to combine and prepare fertilizers of each kind, and to apportion their application according to the rules here laid down. This is a simple detail of execution, and if we are compelled to have re- course to chemical products to complete the ele- ments of fertilization, they will not replace the residues of animal consumption, nor render them useless ; but will allow M. Moll's beautiful for- mula to subsist in ail its truth. — " The purifica- tion of cities by the fertilization of the country." We believe we do not deceive ourselves in affirming that the difficulties of the sewerage question will be removed from the minds of all, as they now are from those who have given 'due attention to the subject. CHARLES MARTEL. Ashford Cottage, Fortess Terrace, Kentish Town. ANALYSIS. AGRICULTURE A SCIENTIFIC PROBLEM. — ALL KNOWN PLANTS ARK COMPOSED OF FIFTEEN ELEMENTS ONLY, WHICH ARE SUBDIVIDED INTO TWO GROUPS, THE ORGANIC AND THE INORGANIC — PARALLEL BETWEEN VEGETABLES AND MINERALS. — THE FORMATION OF THE VEGETABLE DUE TO ORGANIC POWER, WHICH MODIFIES THE ORDI- NARY PLAY OF AFFINITES. — NATURE, UNIFORM IN HER GENERAL LAWS, DOES NOT PASS ABRUPTLY FROM THE MINERAL TO THE VEGETABLE, BUT THROUGH A SERIES OF COMPOUNDS NAMED TRANSITORY PRODUCTS OF ORGANIC ACTIVITY, WHICH ARE EITHER HYDRATES OF CARBON OR ALBUMENOIDS. — THESE PRODUCTS PASS INSENSIBLY FROM ONE STATE TO ANOTHER BY CHEMICAL RE- ACTIONS.— THE ALBUMENOIDS CONTAIN NITROGEN, AND PRESENT THEMSELVES UNDER THREE ESSENTIAL FORMS: INSOLUBLE, SEMI- SOLUBLE, AND SOLUBLE, TO WHICH THE THREE TYPES, FIBRINE, CASEINE, AND ALBUMEN CORRESPOND. — CHANGES THAT OCCUR DURING GERMINATION, AND DURING THE FORMATION OF THE SEED. — THE GREATER PART OF THE WORK OF VEGETATION MAY BE RE- FERRED TO THE RECIPROCAL ACTION OF THE HYDRATES OF CARBON, ALBUMENOIDS, AND MINERALS, THROUGHOUT WHICH THE GENERAL LAWS OF CHEMISTRY PREVAIL. — THE QUANTITY OF MINERAL MATTER CONTAINED IN VEGETABLES IS IN PROPORTION TO THE ACTIVITY OF EVAPORATION. — THE DISTRIBUTION OF THE MINERAL MATTER IN VEGETABLES OBEYS FIXED LAWS. — DEFINITION. — VEGETABLES ARE COMBINATIONS OF A SUPERIOR ORDER TO MIN- ERAL COMBINATIONS, BUT, LIKE THEM, DEPENDENT UPON THE AS- SOCIATION OF THE FIRST ELEMENTS UNDER THE INFLUENCE OF THE GENERAL LAWS OF CHEMISTRY. 1 LECTURE FIRST. In consequence of the persevering efforts given to the study of plants of late years, agricultural produc- tion has been raided to the rank of a scientific problem. It is in this spirit that I have for many years studied it at the Museum of Natural History. Here, my lan- guage will be more simple, familiar, and practical ; it will, nevertheless, retain its scientific character, science being the essential basis of every thing I have to tell you. If we seek to define the conditions which determine vegetable production, the influences which modify its growth, and the forces which govern its manifestations, we must commence by going back to the elements of vegetables themselves. We must separate from the vegetable its organic individuality, and consider only the chemical combinations of which it is the seat and the result. The analysis of all known vegetables or the products extracted from them, leads to this very unexpected fact, — that fifteen elements only concur in these innu- merable formations. These fifteen elements, which, 2 alone, serve to constitute all vegetable matter, are sub- divided into two groups : — First — The organic elements, which are encountered only in the productions of organized beings, and the source of which is found in the air, and in water. They are Carbon. Oxygen. Hydrogen. Nitrogen. Second — The mineral elements, which resist com- bustion, and which are derived from the solid crust of the globe. They are Potassium. Phosphorus. Sodium. Chlorine. Calcium. Iron. Magnesium Manganese. Silicium. Aluminium. Sulphur. Vegetables are, in fact, and from the special point of view where we place them, only the varied combi- nations of which these fifteen elements are susceptible. In the same way that a language expresses our most delicate and profound thoughts, as well as the meanest, by means of the small number of letters which compose its alphabet — so do vegetable productions assume the most varied forms and dissimilar properties by means of these fifteen elements only, which compose the true alphabet of the language of nature. Now, if it be so, we are justified in likening the 4 vegetable to a mineral combination, a more complicated one, doubtless, but which we may hope to reproduce in every part, by means of its elements, as we do with the mineral species. This proposition, how astonishing soever it may appear to you, is nevertheless the exact truth. To prove it to you, permit me to establish a parallel between vegetables and minerals, from the dif- ferent points of view which more especially character- ize the latter. We will commence with their mode of formation and growth. First, we perceive only differences. A crystal sus- pended in a saline solution, grows by the deposit of molecules on its surface, similar in composition and form to those which constitute its nucleus. These molecules, diffused through the solution, obey the laws of molecular attraction, and thus increase the mass of the primitive crystal. The vegetable, on the contrary, does not find diffused vegetable matter in the atmosphere, nor in the soil with which it is in contact. Through its roots and leaves it derives its first elements from without, causing them to penetrate into its interior, and there mysteriously elaborates them to make them ulti- mately assume the form under which they present themselves to our eyes. We can, nevertheless, say that the process of vegeta- ble production has something in common with the for- mation of a mineral. For in both cases we see a cen- tre of attraction, which gathers up the molecules, &c, received from without. In the more simple case of the mineral, the combination of the elements is previously accomplished; only a mechanical grouping takes place. In the more complex case of the vegetable, the combi- nation and mechanical grouping are effected at the same time, and in the very substance of the plant. In both cases a formation is engendered by the union of definite or definable material elements. From the point of view of composition, vegetables appear at first more simple, since they are derived from fifteen elements only, while at least sixty concur in the production of minerals ; but in reality they are more complex, since each plant always contains the fifteen elements at once, while minerals, taken individually, never contain but a very small number, five or six at most. Among vegetables, the combination is also more intimate. In minerals, each of the constituents pre- serves up to a certain point, its individual properties. In the sulphates, for example, it is easy to prove the presence of sulphuric acid by adding baryta to it, which gives the insoluble precipitate of sulphate of baryta in these salts as well as in sulphuric acid itself. Besides, in thus withdrawing the sulphuric acid from a sulphate, we have not destroyed the sulphuric acid, we have only displaced it. But with the group of elements which form a vegetable, it is not so ; in them, all individual character disappears. Who can perceive the carbon, the nitrogen, the potassa, &c, which constitute the plant? Only the whole manifests its properties, and we cannot separate an element from it, except by destroying it 6 past recovery. Notwithstanding these essential differ- ences, we have, nevertheless, in both cases, to do with material combinations, that is to say, with phenomena of the same nature, one of which is more complicated than the other ; they are two distant terms of the same series. Let us conclude this parallel by comparing the forces which, in both cases, determine the grouping of the elements. When attraction is exercised at great dis- tances, in the planetary spaces, for example, it depends only on the reacting masses, and not upon their nature ; when, on the contrary, attraction is exercised in contact, as in chemical combinations, it depends at the same time upon the mass and the nature of its elements. This new and more complex form of general attraction is called affinity. Gravitation, the first term of the series, which we call universal attraction, governs and harmonizes the movements of the stars ; affinity, the second term of this same series, regulates the play of mineral combinations. If we examine the formation of vegetables from this point of view, we shall see that it represents a still more complicated case of universal attraction, a third term of the series, if I may be allowed the expression. Here, in fact, the result depends at the same time on the re-acting masses, on the nature of the elements present, and on the action of a new force, situated in the embryo, which diffuses itself from thence through- out the vegetable, and impresses its special stamp upon the combination produced. Take two seeds of the same sort, having the same weight, remove from each of these seeds a morsel also of the same weight, only let one include the embryo in the amputation, and in the other let the embryo be left out, and take instead a fragment of the perisperm, then put both upon a wetted sponge. The seed without embryo will soon enter into a state of putrefaction, the other, on the contrary, will give birth to a vegetable capable of absorbing and organizing all the products resulting from the disor- ganization of the first. There is then in this embryo a new power, of organic essence, which modifies the ordinary course of affinities, and impresses upon the combinations present a special form, of which it is itself the prototype. The formation of the vegetable is not the only case where foreign forces come thus to modify the ordinary play of affinities. Mix hydrogen and nitrogen together in the dark, there will be no combustion. Submit the mixture to the action of the solar rays, an explosion immediately takes place, and the gaseous mixture is replaced by a new product — hydrochloric acid. Here then are two elements incapable of entering into com- bination by themselves, but which acquire this faculty by the intervention of a foreign force — light. Min- eral chemistry abounds in examples of this kind. In the greater complication of vegetables under these different relations, I consider it then to be correct not to see a sufficient reason for believing that nature has 8 traced a line of absolute demarcation between minerals and vegetables, nor to admit that the laws of their for- mation have nothing in common with those better known laws which regulate the productions of the inorganic kingdom. I think, on the contrary, that nature is uniform in her general laws, and that by attentive ob- servation aided by experiment, we may arrive at know- ing them in all their effects. I perceive then nothing irrational in the attempt to arrive at the artificial reali- zation of the conditions in which they are exercised to produce vegetables, as science has already succeeded in doing with minerals. This conclusion will acquire, I hope, a stronger and stronger evidence as we pene- trate deeper in our researches, and I shall at once give a very striking confirmation of it, in showing you that nature does not pass suddenly from the mineral to the vegetable, from crude matter to organized matter, but that there exists, on the contrary, a class of compounds which lead us insensibly from the one to the other, and form the bridge which unites these two series of pro- ductions. These compounds which, for this reason, we name transitory products of organic activity, range themselves in two different groups — hydrates of car- bon and albumenoids. The following is an enumera- tion of them. 9 TRANSITORY PRODUCTS OF ORGANIC ACTIVITY. Hydrates of Carbon. Albumenoids. ta«b-...{jj5*"> }Kbn„e. ( Gum Tragacanth, "> Semi-Soluble 1 Mucilages, >• Caseine. ( Pectine, ) ( Gum Arabic, } Soluble. . . . < Dextrine, . >- Albumen. ( Sugars, ) Let us first examine the hydrates of carbon. Considered separately, these bodies appear very un- like each other. Cellulose, which is the prime material of all vegeta- ble tissues, is hard, insoluble in water, and resists the action of most re-agents. Starch presents itself in globules formed of concen- tric layers. It swells and forms a jelly with boiling water, or with a weak solution of potassa. Tincture of iodine turns it blue. Pectine also forms a jelly with water, but it exhibits no trace of organization, and iodine does not turn it blue. Mucilages swell in cold water, but do not dissolve. Gum Arabic dissolves in cold water. Lastly, Sugars dissolve and crystallize, thus present- ing one of the essential characteristics of mineral mat- ters. Thus all these bodies form a regular series, of which the types I have characterized arc only distant terms. 10 But in nature we find all the intermediates by which we can pass insensibly from each one to that which fol- lows it. It is thus that cellulose presents itself to us under very different states of cohesion, from the wood and perisperm of the date, where it is extremely hard, unto the young shoots of all kinds of vegetables, and the skins of fruits, where it is not more solid than starch paste. The latter which in the apple, potato, and wheat, is in solid globules, and isolated like grains of sand, is found in a viscid state in other plants, and thus passes gradually to the form of gums and mucilages. Butween the latter and the sugars that crystallize, we find the uncrystallizable sugars, &c. But the analogies which these bodies present with each other do not stop here. It is, in fact, possible to convert them artificially from one into another by the very simple re-actions of the laboratory. Under the influence of dilute acids and prolonged boiling, all are resolved into grape sugar, which seems to be the least organized form, the nearest to mineral nature that the type can assume. As if to give a superior reason to all these approximations, elementary analysis assigns one and the same formula to all the compounds. Each contains twelve equivalents of carbon united to the ele- ments of water, and may be thus represented — C 12 (HO) n (Carbon.) (Water.) which entitles them to the denomination of hydrates of 11 Beside this series of ternary compounds, we also find in all vegetables, the albumenoids which, to the three elements above indicated, join a fourth, nitrogen, in an important quantity, and two others, sulphur and phosphorus, in very small proportions. These compounds, much more complex than the first, present themselves under three essential forms : insolu- ble, semi-soluble, and soluble, to which the three types, fibrine, caseine, and albumen respond. Like the pre- ceding, they are met with in nature under very varied conditions, and may be converted, one into another, by the reactions of the laboratory. The hydrates of carbon and the albumenoids form then two parallel series, which exist side by side in the substance of all vegetables, and which are constantly undergoing the various transformations of which they are susceptible. Let us show what takes place during the germination of a grain of wheat. The hydrate of carbon exists in the dried grain under the form of starch, and the albu- menoid under the form of fibrine or gluten. In pro- portion as the water penetrates the perisperm, it swells, becomes milky, and then it contains albumen, and dex- trine, and true gum. Subsequently, when the blade is elongated, when the leaf begins to respire, you will find sugar and cellulose, which are produced at the expense of the original starch. By the side of these bodies you will find albumen derived from the gluten. Let us examine on the other hand what takes place 12 during the formation of the seed. In beet-root, for ex- ample, sugar exists. In proportion as the seed is formed the sugar disappears, but on the other hand, the seed is full of starch. During the foliaceous life of the plant, its juice contains albumen ; when the seed is formed, the greater portion of the albumenized principle is found concentrated in an insoluble form. We are then fully justified in believing that these bodies are being constantly transformed into each other in the very substance of the vegetable, and that they are like the several steps of a ladder, by which crude matter gradually ascends to the rank of completely organized matter. But we have - seen that in the laboratory these trans- formations are effected by energetic chemical agents. What can be the cause which determines these same effects in the substance of the plant ? When sulphuric acid converts baryta into the sulphate of that base, it combines with it, and there no longer exists either baryta or sulphuric acid. The two con- stituents are confounded in the product of the combi- nation, which is sulphate of baryta. When the same acid converts starch or cellulose into sugar, things do not proceed exactly in the same man- ner. After the transformation, we find the acid wholly free. By its presence alone it acts like the solar ray upon the mixture of chlorine and hydrogen : and sul- phuric acid is not the only body which possesses this property. The albumenoids, of which we have just 13 spoken, possess it in a higher degree, especially when they have begun to undergo a change by contact with the oxygen of the atmosphere. Putrid gluten rapidly converts considerable quanti- ties of starch into dextrine and sugar, and that without being itself disturbed by the exercise of its own modi- fications. The cause of the changes which the hydrates of carbon undergo in the substance of vegetables resides therefore in their encounter with the albumenoids, which are themselves modified under the influence of water, the oxygen of the atmosphere, and the mineral agents derived from the soil. We may then, finally, refer the greater part of the work of vegetation to the reciprocal action of the hydrates of carbon, albumenoids and minerals. You perceive that all through this extremely com- plicated chemical operation, we always encounter the application of the general laws of chemistry, for the actions of contact are not peculiar to vegetables. They are also frequently encountered in the reactions which are effected without organic agency, only they predom- inate in the phenomena of vegetable life. The study to which we devote ourselves therefore warrants the parallel we have drawn between minerals and plants, from the point of view of the superior laws of their production. I shall conclude by confirming this resemblance, and showing you that the separation in the substance of the vegetable of the various elements composing it, is submitted to a law as well determined, 14 I may say, almost as geometrical, as the arrangement of the molecules in a crystallization. Let ns begin with the minerals. Considered as a whole, they are more abundant in grasses than in trees. The latter contains only 1 per 100 upon an average, while grasses contain from 7 to 8 per 100. The reason of this is very simple. In a salt marsh, the quantity of salt deposited in summer is more con- siderable than that produced in winter, because during summer the temperature being higher, the evaporation is more active. So also in vegetables, the quantity of mineral matter they contain is great in proportion to their evaporation. Now herbage being in contact with the atmosphere in every part, it is the seat of an evapo- ration much more active than that in trees, which con- tain completely sheltered organs. We find a rigorous application of this law in the tree. The sapwood con- tains less mineral matter than the heart, the heart less than the bark, the bark less than the leaves. In the green leaves of trees there is less than in the leaves that fall in autumn. In leguminous plants, the pod is richer than the seed, and in the seed there is more in the skin than in the bean. The distribution of mineral matter in the sub- stance of a vegetable obeys therefore an invariable law, it is in direct relation with the activity of evaporation. If we examine what takes place with regard to the nature of the elements, we see that here also fixed lavvs prevail. Phosphoric acid, potassa, and magnesia pre- 15 vail in the seeds, the alkaline earths and iron on the contrary prevail in the stalks. The alkalies increase in proportion as we approach the fruit and young shoots. They are much less abundant in those organs which are old and have less vital activity. Phosphoric acid is disseminated in a nearly uniform manner throughout the vegetable, and suddenly increases when it arrives at seeding. As to the organic elements, the laws are no less pre- cise. Carbon, oxygen, and hydrogen, which, in the state of hydrates of carbon, form the general framework, are found diffused nearly uniformly throughout all the organs. Nitrogen, which forms an essential portion of the albumenoids, of which the most important part con- sists in the active task of the formation of the tissues, is found in the greatest quantity in all the recent shoots, and especially in the seed, the last product of annual vegetable activity. We have arrived in this lecture at denning vegeta- bles as material combinations of an order superior to mineral combinations, but like them, dependent upon the association of the first elements under the influence of the general laws of chemistry. This definition leads us invincibly to the hope of producing them artificially, and in every part, by means of their elements placed at our disposal, under conditions where they are suscep- tible of assuming this kind of combination. It remains for us to examine the means we can employ to attain this aim. ANALYSIS. THE ORGANIC ELEMENTS OF VEGETABLES ARE OXYGEN, HYDRO- GEN, CARBON, AND NITROGEN. — UNDER WHAT INFLUENCES AND CONDITIONS THESE ELEMENTS ENTER THE VEGETABLE FROM WITH- OUT. — CARBON ENTERS THE PLANT UNDER THE FORM OF CARBONIC ACID, WHICH IS ABSORBED BY THE ROOTS, AND BY GREEN LEAVES UNDER THE INFLUENCE OF SOLAR LIGHT, AND EMITTED FROM THE LEAVES DURING DARKNESS. — OXYGEN IS DISENGAGED FROM THE LEAVES IN EXACT PROPORTION TO THE QUANTITY OF CARBONIC ACID ABSORBED. — WHAT BECOMES OF THE CARBONIC ACID ABSORBED? — IT IS DECOMPOSED, ITS CARBON FIXES ITSELF IN THE VEGETABLE WHILE ITS OXYGEN IS REMOVED. — UNLIMITED SUPPLY OF CARBONIC ACID FROM THE RESPIRATION OF ANIMALS, FROM THE FORMATION OF PYRITES, AND FROM VOLCANOES. — CARBON FORMS ABOUT 50 PER CENT. OF DRIED PLANTS — THE QUANTITY FIXED DEPENDS UPON THE EXTENT OF THEIR FOLIAGE. — WATER THE SOURCE OF THE OXYGEN AND HYDROGEN IN PLANTS; IS SOMETIMES DECOMPOSED, LIKE CARBONIC ACID, THAT ITS OXYGEN MAY BE ELIMINATED.— PLANTS CONTAIN ONLY SMALL QUANTITIES OF NITROGEN, BUT IT IS AN INDISPENSABLE ELEMENT. — THEY CONTAIN MUCH MORE NITRO- GEN THAN IS SUPPLIED BY MANURE — WHICH EXCESS IS OBTAINED FROM THE ATMOSPHERE. — THE NITRATES OCCUPY THE FIRST RANK AMONG THE NITROGENOUS MATTERS USEFUL TO VEGETATION.— NEXT COME AMMONIAC A L SALTS. — SOME CROPS DO NOT REQUIRE THE ADDITION OF NITROGEN TO THE SOIL. — THE CEREALS REQUIRE THIS ADDITION IN LARGE QUANTITIES. 17 LECTURE SECOND. In our first discourse we arrived at the consideration of the vegetable as a material aggregate, having the closest analogy with chemical combinations. We have seen that the laws which preside at its formation differ in no respect, in a philosophical point of view, from those which regulate the production of the compounds of mineral chemistry. If it be so, in order to penetrate the mysteries of the production of vegetables, the first thing we have to do is to ascend to the origin of their elements, and after- wards inquire in what conditions, and under what influences, these elements enter from without, and com- bine together in a special manner to produce the vege- table. Let us commence this study with the organic ele- ments, which are : Carbon. Oxygen. Hydrogen. Nitrogen. The carbon cannot penetrate vegetables, except under 19 the form of carbonic acid. This gas arrives by two different ways. 1st. By the roots, which draw it from the soil, where it is produced by the spontaneous decomposition of organic matters. 21. By the leaves, which take it from the atmos- pheric air, where it exists permanently. In order for the carbonic acid to be absorbed, it is necessary that four essential conditions be realized. The first is of organic nature, and resides in the green color of the organs of vegetables. The petals of flowers which are variously colored do not absorb carbonic acid : the leaves, the bark, and the pericarp of green fruits, on the contrary, absorb it in abun- dance. In the generalization of this fact it may be objected that purple leaves, and leaves that are almost white, exist, which also absorb carbonic acid from the air. I find the reply in a recent work by M. Cloez. This chemist has shown that the leaves referred to, not- withstanding their different aspect, contain large quan- tities of green matter. It is, then, safe to say that the function under consideration depends upon this green matter. Whatever the color of the organs, carbonic acid is never absorbed in the absence of solar light. This second external condition of the vegetable is also as indispensable as the first. Would you wish to prove it ? Pass a current of air into a large receiver contain- ing a young vine with its leaves, and connected with an 20 apparatus capable of measuring carbonic acid. You will perceive, as M. Boussingault has done, that in the sun, the atmospheric air, in passing over the green leaves, loses nearly one-half its carbonic acid, while in the dark, on the contrary, it gains a very considerable quantity. Not only, then, the leaves absorb no car- bonic acid in the dark, but they also constantly emit it, to the destruction of a portion of their substance. "When the leaves are attached to the plant, they disen- gage more carbonic acid than when they are removed, because that which the roots derive from the soil, not being decomposed in the vegetable, comes then to be exhaled from the surface of the leaves. A third indispensable condition, also, is the interven- tion of a certain temperature. MM. Grratiolet and Cloez have shown that the leaves of the potamogeton, which, in water at 54° F., disengages abundance of oxygen, ceases to do so when the temperature is low- ered to 37° F. Now, as we shall soon see, this disen- gagement of oxygen is precisely the certain index of the absorption of carbonic acid. Finally, the fourth and last condition of the pheno- menon is the presence of oxygen in the atmosphere in which the leaves are placed. Theodore de Saussure has proved that in an atmosphere of hydrogen or nitro- gen, containing carbonic acid, this gas is not absorbed by plants. On the contrary, the phenomenon manifests itself whenever oxygen forms a portion of the surround- 21 What becomes of the carbonic acid thus absorbed by plants ? While this substance resists the highest temperatures and the most powerful chemical reducing agents, in the substance of plants this acid is decom- posed, its carbon fixes itself in the vegetable, and its oxygen is removed. Hence the disengagement of oxygen which takes place on the surface of leaves immersed in water. This fact, one of the most impor- tant which science has discovered in this century, has been brought to light by the labors of a whole gener- ation of savants, but it was principally by Theodore de Saussure that the conditions were defined. He saw that the quantity of oxygen emitted was equal in vol- ume to the carbonic acid absorbed, and that minute quantities of nitrogen were disengaged. This disen- gagement of nitrogen, since proved by MM. Gratiolet and Cloez, has recently been denied by M. Boussin- gault. Not wishing to insist upon this point, which has no interest in agriculture, I shall merely remark that, in all the experiments made, one condition, which could alone give value to their results, has been wanting. For it to be legitimate, in fact, to extend to vegetation the facts observed in these experiments, they must be performed upon vegetables in progress of development, constantly increasing in weight, and not upon detached portions, which may, it is true, still give vital manifes- tations, but the ephemeral existence of which is neces- sarily accompanied by special phenomena of destruc- tion. 22 The assimilation of the carbon, so interesting in a physiological point of view, presents only an insignifi- cant interest for agriculture : there need be no fear of its ever failing, for the atmosphere contains an unlimited supply of it. In proportion as vegetation appropriates it, animal respiration, by an inverse effect, restores it in equivalent quantities. This harmony between the two organic kingdoms, first observed by Priestley, and so brilliantly explained by Dumas in his Statistics of Organized Beings, is nevertheless only an infinitely small one among the causes of the permanence of the atmospheric carbonic acid. Among geological phenomena, causes of loss exist which are much more powerful than vegetable absorp- tion. The disintegration of felspars removes colossal quantities of this acid from the air, but volcanoes and the formation of pyrites constantly restore it in quan- tities no less important, so that its composition presents, under this relation, quite a satisfactory stability for agriculture. Carbon enters into the composition of all plants in the proportion of about 50 per 100, when they are dried. It is to this element that the variation in the weight of crops is due. The quantity plants assimilate depends, in great measure, upon the surface of their leaves, and also a little upon their special nature. Experiment has proved that plants which, upon an equal surface of ground, fixed most carbon, were those that presented the greatest foliaceous surface. We 23 have seen, also, that with an equal surface of leaves, plants fix quantities of carbon differing a little accord- ing to the species. The oxygen and hydrogen found in vegetables are undoubtedly derived from water; this latter may be assimilated naturally, as is proved by the existence of hydrates of carbon in the substance of vegetables in which oxygen and hydrogen are found in the propor- tions necessary to form water. But the formation of resins, essential oils, and fat bodies, in which hydrogen predominates, shows that in certain cases, water may be reduced, like carbonic acid, and that its oxygen may be eliminated. Whatever it be, the origin of the oxygen and hydrogen once established, we have no need to dwell on this point, for the plants, not being deficient of water, are in consequence abundantly provided with these two elements. It is not the same with nitrogen. Plants contain it only in relatively very small quantities, but they have an indispensable need of it, and as in certain cases it may fail, it is necessary to study with the greatest care every thing that concerns the assimilation of this ele- ment. First let us show that all plants exhibit in the crops a much greater proportion of nitrogen than there was in the manure supplied to them. The following data taken from " Boussingault's Rural Economy " establish this fact. 24 Plants. ' Potatoes Annual Excess of Nitrogen per Acre. Rotations of Five years. Wheat Clover Turnips ^ Oats ' Beach Oak Birch lbs. 8-36 Forest culture « 29-04 L Poplar Exclusive culture Artichokes 37-84 Exclusive culture Luzerne 182-06 If the crops contain such quantities of nitrogen of which the soil can render no account, we must look to the atmosphere as its origin. The air contains 79 per 100 of elementary nitrogen : nothing appears more rational than to find there the origin sought. But chemists, accustomed to see nitrogen gas offer a great resistance to combination, have at first preferred to re- fuse to it all intervention in the phenomena of vegeta- tion. To restore it to the place which this preconceived opinion, or one founded upon incomplete experiments, had caused it to lose, it was necessary to have recourse to extremely delicate experiments, which it is impossible to describe in this place. I shall therefore content myself with refuting, by arguments derived from extensive cultivation, all the origins whfch the adversaries of the absorption of gaseous nitrogen are compelled to put forth, referring 25 to my works and to my lectures at the Museum those amongst you who desire to know the direct proofs of this absorption. Priestley and Ingenhouz believed in the assimilation of the elementary nitrogen of the atmosphere. Theo- dore de Saussure having proved the existence of ammo- nia in the air, attributed to this compound the faculty of supplying nitrogen to vegetables. Ammonia does in fact exist in the atmosphere, but the quantity is so small (22 grammes in 1 million kilogrammes), that it is evidently absurd to endeavor to make it play so im- portant a part. The objection has also taken another form. It is urged that the air contains ammonia Rain water dis- solves it, condenses it, and conveys it to the plant, which thus finds it in the soil. If in the place of thus contenting themselves with this vague assertion, they had thought to give it precision by measuring the am- monia in the rain water, and ascertaining the quantity of this water received per acre, they would have found by this way, that the soil receives, as a maximum, about 3 pounds of nitrogen per annum. But to explain the vegetation of luzerne we must account for 182 pounds of nitrogen. The ammonia in rain water is then only infinitely small in relation to the phenomenon under consideration. Ammonia failing, recourse was had to nitric acid, which is formed in the atmosphere by the direct com- bination of oxygen and nitrogen under the influence of 26 electric discharges and during rain storms. And anal- ogous calculations to the preceding show that, by this new way also, 1 acre of land receives 3 pounds of nitrogen, at the most. Nitric acid therefore explains no better than ammonia the excess of nitrogen in the crops. But, it is urged, there may exist in the atmosphere some nitrogenous substance eminently assimilable, which is condensed by rain water, and which has hith- erto escaped analysis. Notwithstanding the utter vagueness of this objection, I have wished to reply to it by direct experiment. I have instituted two similar growths in boxes placed under shelter • one of them was watered with rain water collected by a pluviometer of equal surface to that of the box, and placed apart : the other received similar quantities of perfectly pure distilled water. The crop with distilled water was nearly as large as that obtained with rain water. It is therefore evident that rain water contained nothing susceptible of influencing the development of vegeta- bles. But, since it has been desired to give this importance to the essential products the air may yield to the soil, it will be permitted to me, on the other hand, to con- sider those which the soil yields to the atmosphere; and this time it is from my adversaries themselves that I borrow the bases of my arguments. M. Boussingault had the idea of collecting the snow from the surface of the ground and the terrace of a 27 garden. A litre of water from the first contained 0*0017 gr. of nitrogen, while that from the terrace contained 0*0103 gr. It is certain, therefore, that cul- tivated soil constantly loses nitrogen. If we suppose that the layer of snow examined by M. Boussingault had a thickness of only 0*01 m. it contained in 1 acre, 180 pounds of nitrogen lost to the soil. We sec, then, that the losses the soil is capable of experiencing are quite as important as the gains it may derive from the atmosphere. We must necessarily, then, have recourse to elementary nitrogen to explain the excess in the crops. But, here another subject of discussion presents itself j the nitrogen of the air — is it absorbed naturally by plants, as I have always maintained, or does it take place, as recently suggested, only by the intermedium of nitrification previously accomplished in the soil, which would thus be a real artificial nitre-bed ? Doubt- less, in certain cases, important quantities of nitrates may be produced in the soil • but I none the less per- sist in saying that nitrification cannot account for the excess of nitrogen in the crops. For the 182 pounds to have penetrated into the luzerne by this channel, it would have been necessary to engage 1756 pounds of nitric acid which, itself, to be saturated, must have « combined with 1540 pounds of bases. These 1540 pounds of bases should be found in the crops : but, the latter produced upon combustion, only 1525 pounds of ashes, of which the bases formed 701 pounds, There 28 is, then, at least half the excess that the hypothesis of a nitrification cannot explain. Besides, if it were so, if the nitrogen of the crops came from the nitrogen formed in the soil, is it not evident that an artificial addition of nitrates would pro* duce the same effect as a natural formation ? Now there exists, in fact, some crops, that of wheat, for example, the addition of nitrates to which increases the yield. But there are others, as you may see for yourselves by inspecting the experimental field, upon which nitrates exercise no influence. Peas for example, have not assimilated more nitrogen with a strong manure of nitrates than without the addition of any nitroge- nous compound. It is then quite evident that if, in cer- tain cases, natural nitrification can play a definite part, it may, on the other hand, serve as a general explana- tion of the excess of nitrogen in the crops, and that the true and great origin of this nitrogen resides in the atmospheric nitrogen directly absorbed. And moreover, what is there, in a theoretical point of view, so repugnant to the admission of this absorp- tion ? As we speak of nitrification in the soil, who can deny that in the substance of leaves, where nitrogen undoubtedly penetrates, where it constantly meets with nascent oxygen, ozonised — the formation of nitric acid must be at least as easy as it is in the soil ? And when we perceive these organs endowed with a chemical power sufficient to reduce carbonic acid, is it then inconceiva- ble that they are capable of causing nitrogen to enter •29 into combination more readily than it does in our labor- atories? No! the absorption of nitrogen, proved by experiment, is not irrational, and it is only habit and prejudices that oppose this doctrine, which, alone, is susceptible of giving us the clue to the phenomena of vegetation, and reacting usefully upon agricultural prac- tice. If the nitrogen of the air can contribute to vegeta- ble nutrition, is it to be said that we are not to trouble ourselves about supplying nitrogen to our crops, and that with regard to this element we find ourselves in the same state of security and weakness as with the first three that occupied our attention ? Doubtless no ! Practice on a large scale has proved the utility of nitro- genous manures, and I have myself proved that the yield of the cereals is considerably increased by the introduction of nitrogenous material into the soil. Of all the substances I have tried, the nitrates have always given me the best results, when I have operated on a small scale, and when the quantity of nitrogen supplied to the crops was inferior to that which the yield should have contained. On the large scale, M. Kuhlmann has obtained similar results. But at the experimental farm, at Vincennes, I have observed no difference between the employment of nitrates and of ammonial salts. This is due, doubtless, to the manures I had recourse to, and which I intended for several successive years, having been supplied in very large 30 quantities, and that the plants, always finding in the soil an excess of assimilable nitrogen, prospered as well in one case as in the other. Therefore I do not hesitate to say that I place the nitrates in the first rank among nitrogenous matters useful to vegetation. Next come ammoniacal saits, and, a long way after them, organic nitrogenous matters, which, to act usefully, must be previously converted into nitrates or ammoniacal salts. All that we have said concerning nitrogen may be summed up in the following conclusions, the agricul- tural importance of which cannot be questioned. 1. Generally speaking, the nitrogen of the air enters into the nutrition of plants. 2. In connection with certain crops, especially vege- tables, this intervention is sufficient, and the agricul- turist has no occasion to introduce nitrogen into the soil. 3. With regard to the cereals, and particularly dur- ing their early growth, atmospheric nitrogen is insuffi- cient, and to obtain abundant crops it is necessary to add nitrogenous matters to the soil. Those which best fulfil this object are the nitrates and ammoniacal salts. ANALYSIS. ON THE ASSIMILATION OF MINERAL ELEMENTS WHICH PENETRATE THE PLANT IN AQUEOUS SOLUTION ONLY. — THE MEDIUM FROM WHENCE THE ROOTS OBTAIN THEM. — THE SOU- IS THE SUPPORT OF THE ROOTS, THE RECIPIENT OF THE SOLUTION THAT FEEDS THEM, AND THE LABORATORY WHERE THIS SOLUTION IS PREPARED: IT IS COMPOSED ESSENTIALLY OF THREE CONSTITUENTS — HUMUS, CLAY, AND SAND. — PROPERTIES OF HUMUS: ITS INFLUENCE IN THE SOIL, FIXES THE AMMONIA — IS A CONSTANT SOURCE OF CARBONIC ACID WHICH DISSOLVES THE MINERAL MATTERS, AND IS THE PRINCIPAL AGENT IN SUPPLYING PLANTS WITH THEIR MINERAL CONSTITUENTS. — UTILITY OF CLAY IN ARABLE LAND — IMPARTS CONSISTENCE TO THE SOIL, RETARDS THE PASSAGE OF WATER, FIXES AMMONIA, AND REMOVES A LARGE QUANTI1Y OF SALTS FROM SALINE SOLUTIONS, STORING THEM UP FOR FUTURE SUPPLY.— ESTABLISHES AN EQUI- LIBRIUM BETWEEN SEASONS OF DROUGHT AND RAINY WEATHER.— SAND FORMS PART OF EVERY SOIL; FORMS ITS PRINCIPAL CONSTITU- ENT, COMMUNICATING TO IT ITS PRINCIPAL PHYSICAL PROPERTIES, ESPECIALLY ITS PERMEABILITY TO AIR AND RAIN WATER — IT TEM- PERS THE PROPERTIES OF CLAY. — ELEMENTS OF THE SOIL, WITH- OUT WHICH VEGETABLE LIFE IS IMPOSSIBLE : PHOSPHATE OF LIME, POTASSA AND LIME, WHICH ASSOCIATED WITH A NITROGENOUS SUB- STANCE, AND ADDED TO ANY KIND OF SOIL, SUFFICE TO RENDER IT FERTILE. — CHEMICAL ANALYSIS FAILS WHEN AFPLIED TO SOILS — NECESSITY FOR SUBSTITUTING AN ARTIFICIAL KNOWN COMPOUND IN EXPERIMENT, TO REMOVE ALL SOURCE OF ERROR. — RESULTS OBTAINED— 1. WITH CALCINED SAND ALONE. 2. WITH CALCINED SAND, AND NITROGENOUS SUBSTANCES. 3. WITH CALCINED SAND AND MINERAL SUBSTANCES. — EACH AGENT OF VEGETABLE PRODUCTION EXERCISES A DOUBLE FUNCTION. 1. AN INDIVIDUAL FUNCTION VARIABLE ACCORDING TO ITS NATURE. 2. A FUNCTION OF UNION. — SPECIAL ACTION OF NITROGENOUS MATTER AND MINERAL SUB- STANCES. — RESULTS. —A SOIL CAPABLE OF PRODUCING PLANTS, MUST CONTAIN IN AN ASSIMILABLE FORM, NITROGENEOUS MATTER, PHOS- PHATE OF LIME, POTASSA, AND LIME. — ERRORS COMMITTED IN APPLYING MANURE TO SOILS THE COMPOSITION OF WHICH IS UN- KNOWN.— THE SOURCE OF ERROR REMOVED BY THE EXPERIMENTS NOW DESCRIBED. — PROSPECT OPENED BY SCIENCE TO AGRICULTURE. 31 LECTURE THIRD. The logical order of our inquiries conducts us imme- diately after the assimilation of the organic elements treated of in our last lecture, to the same question in respect to the mineral elements. But these bodies penetrate the vegetable only under the form of aqueous solution, and before showing you the effects they pro- duce, when absorbed, it is necessary that I should make known to you the medium from whence the roots derive them. The soil is, at the same time, the support of the roots, the recipient of the solution that feeds them, and the laboratory where this solution is prepared. It is com- posed essentially of three constituents, which concur, each in a certain proportion, to give to the whole the properties which I proceed to enumerate. They are humus, clay, and sand. Humus is of organic origin. It possesses a deep brown color, almost black. It is the cause of the dark color of vegetable mould. It dissolves in alkalies, with which it produces an almost black liquor. Acids sep- arate it from this solution under the form of a light, 32 33 flocculent precipitate of a deep brown color. While it remains moist it will dissolve slightly in water, but when once it is dried it will no longer dissolve in it. It does not crystallize ; and under the action of heat it is decomposed, leaving a carbonaceous residue. Such are the properties which chemists assign to humus, but there is nothing very characteristic, noth- ing to show that humus is of a very definite chemical species. In fact, chemistry experiences the greatest difficulties whenever it attempts to specify a body which does not crystallize, and which is not volatile. For in that case we can proceed only by way of induction. This is what we shall attempt to do in order to arrive at a clear idea of the constitution of humus. If we submit to the controlled action of heat the hydrates of carbon described in our first lecture, sugar for example, it will not be long before we produce a brown body which is designated by the name of cara- mel. The chemical composition of this caramel is nearly the same as that of the sugar from whence it is derived, showing that the only difference existing be- tween them consists in the loss experienced by the sugar of a certain quantity of water. Sugar being represented by the formula C 12 H 12 O 12 or C 12 (IIO) 12 , caramel is expressed by C 12 (HO) 9 . When we act upon sugar with hot baryta water, we obtain another brown body, apoglucic acid or assamare, containing still less water than caramel. By the action of an excess of alkali upon sugar we descend to melassic acid, which •3 34 always contains hydrogen and oxygen in the propor- tions necessary to form water, bnt in still less quantity than the preceding bodies. It is then possible, by the reactions of the laboratory, to remove successively from the hydrates of carbon, and, as it were, molecule by molecule, the greater part of the water that enters into their composition, without their departing in consequence, from the original type, as in these various products the carbon always remains associated with the elements of water, and all may be represented by the general formula of hydrates of car- bon C 12 (HO) n . Now this gradual decomposition of the hydrates of carbon goes on incessantly in arable land, where vege- table debris of all kinds is buried. Humus is nothing more than the ordinary limit of this decomposition. Some chemists assign to it the formula C u H 9 O 9 ; but it is rather a collection of every kind through which the progressive decomposition of the hydrates of carbon passes, and I have no doubt that we can go much beyond the formula expressed by C 24 (HO/. Coal, studied from this point of view, fur- nishes us with valuable instruction. Death thus realizes a series of phenomena exactly the reverse of those produced in the substance of liv- ing vegetables. For while, among these latter the car- bon, reduced from carbonic acid, fixes upon the elements of water in greater or lesser proportion to produce all the hydrates of carbon,-— in the soil, on the contrary, 35 the water separates little by little from the carbon to arrive finally at leaving it almost in a state of liberty. If the chemical properties of humus are difficult to characterize, its presence in the soil is none the less useful to agriculture. It absorbs water with great energy, and greatly increases in volume under its influ- ence. By this property it contributes to maintain the coolness of the soil by retarding its drying. When humus is put in contact with an ammoniacal solution, it removes the ammonia from it, hue retains it only by a very feeble affinity, for it is only n cessary to introduce a large quantity of water to recover it. However, it does not fix combined ammonia ; that is to say, when it is combined in ammoniacal salts. Mixed with carbonate of lime or marl, does it acquire the faculty of fixing ammoniacal salts also ? By this manner of comporting itself with ammonia and ammoniacal salts, the utility of which are recog- nized in our previous lecture, humus renders important services to vegetation. It prevents, at least partially, the loss of the ammonia which results from the spon- taneous decomposition of nitrogenous organic matters buried in the soil. Moist humus, exposed to the air, undergoes a slow combustion which makes of it a constant source of carbonic acid. The part played by this acid in vegeta- ble nutrition is of the highest importance, as was shown in the preceding lecture : still the small quantity produced by the decomposition of humus can scarcely, 86 by its direct absorption, favor the development of plants which otherwise find it abundantly in the atmosphere. Besides, we do not attach very great importance to the humus under this relation. But the carbonic acid which it unceasingly produces in the soil fulfils another function, incomparably more useful. It serves to dis- solve the mineral matters, phosphates, alkalies, lime, magnesia, iron, etc. It causes the disaggregation of fragments of rocks containing useful matters which water alone cannot attack, and which, without it, would remain inert in the soil. Carbonic acid derived from humus is then, as a whole, the principal agent of solu- tion capable of supplying plants with their mineral ali- ment. Clay intervenes no more directly than humus in veg- etable nutrition. Nevertheless, its presence in arable land is of unquestionable utility. Clay is a hydrated silicate of alumina, retaining its water with great per- sistence, forming with it a very plastic paste, which serves to fabricate pottery. Its presence in the soil imparts consistence to it, diminishes its permeability, and maintains its coolness by retarding the passage of water. Like humus, clay fixes ammonia by a kind of capillary affinity, but it also possesses this property with regard to all saline solutions. By its agency the solu- ble salts resist flowing waters; still more, it removes from highly charged saline solutions a much larger quantity of salts, and yields them up again to the water when it arrives in sufficient quantity. In a very fertile 37 soil, that is to say, one much charged with soluble salts, when little water is present, the solution it produces miirht attain to such a decree of concentration as to oecome injurious to plants. In this case, the clay, by appropriating the greater part of the salts, sufficiently weakens the solution. If, on the contrary, abundant rain fails, the clay gives up what it had previously taken, and thus re-establishes the equilibrium between seasons of drought and rainy weather. In these circumstances, the clay acts as a sort of automatic granary, which, out of its abundance, stores up superfluous aliments to distribute them again when scarcity prevails. It regulates the strength of the ali- mentary solution, as the fly-wheel of a steam engine regulates its motion. As for the sand, it forms part of all soils, of which it is the essential constituent. It communicates to the soil its principal physical properties, and its permea- bility to air and water. It tempers the properties of the clay, and by its association with it, realizes the con- dition most favorable to the development of plants. We have studied the inert elements of the soil, those which enter into its composition to at least 99 per 100, but which, nevertheless, concur in vegetable production only by their physical properties. It now remains for us to examine the elements which exist in but very slight proportions in the soil, but of which the part played is capital in the life of plants, since without them vegetation is impossible. 38 Here, as with the organic elements, we commence by removing from the discussion the principles which are found in sufficient quantity in all soils, and of which, consequently, agriculture has no need to concern itself. For this reason we pass by in silence, silica, magnesia, iron, manganese, chlorine, and sulphuric acid. Phosphate of lime, potassa and lime remain. These are the essential minerals, such as, associated with a nitrogenous substance and added to any kind of soil, suffice to render it fertile. With them we can actually fabricate plants. At the commencement of my experiments, fifteen years ago, struck with the weakness of the old chemists with regard to the problems raised by vegetation, a weakness which I shall account for in my next lecture, I decided upon attempting a new method. The soil could not be known with accuracy, for chemical analy- sis had completely failed in ascertaining its composition. I resolved to substitute for it an artificial mixture, all the elements of which were clearly defined. In this way I arrived at producing vegetation, in pots of china bis- cuit, with calcined sand and perfectly pure chemical products. In these ideal conditions I instituted the four follow- ing experiments : — 1. Calcined sand alone. 2. Calcined sand with the addition of a nitrogenous substance. 3. Calcined sand with minerals only (phosphate of lime, potassa and lime J. 39 4. Calcined sand with the minerals and a nitrogen- ous substance. I sowed on the same day, in each pot, 20 grains of the same wheat, weighing the same weight, and kept the soils moist with distilled water during the entire duration of vegetation. At the harvest I observed the following facts. In the sand alone the plant was very feeble ; the crop dried weighed only 93 grains. In the nitrogenous substance alone, the crop, still very poor, was however better; it rose to 140 grains. In the mineral alone, it was a little inferior to the preceding; it weighed 123 grains. But with the addition of the minerals and the nitro- genous substance, it rose to 370 grains. From this first series of experiments we conclude that each of the agents of vegetable production fulfils a double function : 1. An individual function variable according to its nature, since the nitrogenous matter produces more effect than the minerals, and as either, employed separ- ately, raises the yield above what the seed could pro- duce by itself in pure sand. 2. A function of union, since the combined effect of the nitrogenous substance and the minerals is very su- perior to what each of these two agents produces sep- arately. ]>ut it is not sufficient to prove the relation of de- pendence which exists between the action of the nitro- 40 genous matter and the minerals, taken en masse ; we must take account of the special action of each of them. Let us then institute new experiments, in which we associate variable mineral mixtures with a nitrogenous substance, always the same, and employed in the name quantity. Let us commence by suppressing, among the miner- als first employed, the phosphate of lime, and in its stead associate, with the nitrogenous matter, a mixture composed only of lime and potassa. In these new conditions, vegetation is not possible. The seeds germinated and scarcely arrived at 4 inches in height; the plants withered and died. A mixture of potassa and lime is therefore injurious to vegetation. To make it useful, phosphate of lime must be added. Do you wish to prove it ? Make a fresh experiment with the same agents and a trace of phosphate of lime, 0.01 grains in 1000 grains of soil, and you will obtain a plant — meagre, it is true — but which does not wither and die. When the phosphate of lime is in sufficient quantity, the crop rises to 370 grains, as before stated. There exists, then, between the phosphate of lime on the one part and the potassa and lime on the other, a relation of unity analogous to that which we have shown to exist between nitrogenous matter and miner- als. To render an account of the part played by potassa, let us make a fresh experiment, from which we will banish this alkali, and in which, consequently, the soil 41 will be fertilized with the nitrogenous matter and a mix- ture of lime, and phosphate of lime. Here the plant does not die, but the crop is inferior to that given by nitrogenous matter alone j it descends to 123 grains. Potassa is then an indispensable ele- ment, in a less degree however than phosphate of lime, since its absence does not, as with the preceding, cause the death of the plants. Seeing that soda replaces potassa in most industrial uses, we inquire if it might not do the same with re- spect to vegetation. Experiment has defeated this hope. In the absence of potassa, soda exercises no influence upon the yield, which remains just the same, whether it intervenes or not. It is then indisputable that, with regard to wheat, potassa is of the first necessity, and that soda cannot be substituted for it. It remains to explain the part played by lime. Here the question becomes much more complicated. The method we employed just now, and in which we made only pure and artificial products to enter, leads us to results of little importance only. An experiment made with nitrogenous matter, phos- phate of lime, and potassa only, gave a crop of 340 grains, while we obtain 370 grains with the complete manure, by which I understand — the mixture of nitro- genous matter and the three essential minerals : phos- phate of lime, potassa and lime. This slight difference seems to indicate that lime plays only a secondary part. Nevertheless, agricultural practice obtains very good 42 effects from it. We must then seek by other ways to discover what may be the nature of its action. If wo substitute a mixture of sand and humus, for pure sand without lime, the yield remains, like the preceding, equal to 340 grains. In the absence of lime, the humus has, then, no action, either useful or injurious. But if we add lime (in the state of carbon- ate) in this same experiment, the yield immediately rises to 493 grains. The lime which, in the absence of all organic matter, influences the yield in but an insignificant manner, manifests, on the contrary, a very decisive action in the presence of humus, which produ- ces no effect of itself, when alone. There exists, then, between lime and humus a remark- able relation of unity. All the experiments lead us to this final conclusion : that the soil, to produce plants, must contain, under an assimilable form, a nitrogenous matter, with phosphate of lime, potassa and lime, and that to insure the eflicacy of this latter, the presence of humus is indispensable. You will now comprehend, without difficulty, why agricultural experiments made upon soils more or less fertile have not led, -n a> nips . . eat . . . y ferti' ygood a 3i -d ^ 9 CO e SS C P OR ffl CO GO Ci C5 CO CS co e ZD CO O O CO Oi § 8 I-* CO o O CO CO a o 00 CO to • 1— t 1—1 5 Oi a *>. ►* >-' CO ►*»■ CO o CH> to CO a a Oi »— » ^ 2. •0-i "3 .: o a E 3 00 Sand. 6 24 8 7 22 32 Soil from Gascogne. 55 32 9 6 8 22 " Soil from Bretagne. 4 29 16 9 18 f< ** Soil of Vincennes. 11 35 20 28 28 32 " The soil from the landes of Gascogne, without ma- nure, was not more fertile than calcined sand: with complete manure, its yield was equal to that of calcined sand with humus and complete manure, this soil there- fore contained humus. Reasoning in the same manner with regard to the elements, we see that it contains neither nitrogenous matter, nor potassa, nor lime, since, in their absence, it is not more fertile than calcined sand. On the other hand, it contains traces of phosphoric acid, for in the I experiment where it was not added, it yielded a light crop, while in the sand the plants invariably perished. As for the soil of the landes of Bretagne, these ex- 59 periments show it contains humus, a little nitrogenous matter, a little potassa, and very small quantities of phosphates. The soil of Vincennes, examined in the same man- ner, showed itself to be rich in humus, phosphates, po- tassa and lime, but poor in nitrogenous matter. These are positive data, which we can employ in fer- tilizing soils. Let us now see to what extent they were verified in practice on a large scale. 60 r S. p 3 3 00 oo Or CO 00 O o o 00 O III O Or O O 5 * o c 2 3 13. S 61 This table shows that, without phosphates, the crop was nearly equal to what it was with a complete manure : that without potassa it sensibly diminished, and that without nitrogenous substances, it was very inferior. These results are exactly like those derived from experiments on a small scale. But do you wish to see with what precision these results agree ? Sup- pose the crop with complete manure equal to 35, as it was on the small scale, and calculate the others with reference to that. You will thus be led to the following comparison : Complete Manure. Complete Manure. Without Nitrogen Matter. Without Without Potassa. Phosphates. Cultivation on small scale. 35 20 28 28 Cultivation on large scale. 35 21.7 30 32 I will ask you, is it possible to attain to a more perfect concordance, and is it not the most satisfactory proof of the excellence of the method I have com- municated to you ? The plant therefore becomes in our hands one of the most perfect instruments of analysis, the only one, in the present state of science, susceptible of making known, practically, the composition of soils. But I shall give to this proposition a still more striking 62 demonstration, by snowing you to what extent this test goes. We have seen that, in calcined sand and complete manure without phosphates, we succeed in causing the death of plants. In the soil from the landes of Gras- cogne the same compound gave a crop equal to 6, which proves, as we have stated, the presence of small quantities of phosphates in the soil. To lcwt. of calcined sand and complete manure without phosphates, add only T £^ of 1 per 100 of phosphate of lime, that is to say, y^oiro of tne weight of the soil. Immediately the yield rises to 6, as in the soil of the landes of Glascogne. We are then correct in saying that vegetation re- veals to us with certainty, in this soil, the presence of T ooVoo of phosphate of lime. What chemical process, let me ask, can attain to such limits ? The accuracy of this method, in relation to the other elements, is no less remarkable. ti^ti °f potassa cause the yield to pass from 8 to 32 : tw ^q ^ Q tr 3 CO P GO /—-*■—> jo GO © & p S : 3 3 3 P If*. O JO CS ^T £2,3 © » Ol 03 o 2 CO <5~2. o < 3 o o V =-99 © < ' o © « CD 3; Si 5< to CD J^ CD c LO O) io to C? O M i-i co »ii To* CO c D o © a n- • -d CO M> Cn •— CO t3 2. "3 90 You see that the balance is strikingly exact with re- gard to the nitrogen and the phosphoric acid ; as to the potassa and lime, it accumulates for the benefit of the soil. There is, then, nothing surprising in the fact of this system maintaining the fertility of the soil, as nothing is lost : but upon what conditions ? To obtain these eight tons of manure required every three years, we must raise cattle : to feed them requires pasture : and to maintain this pasture requires irriga- tion. It is then, in fact, to the water of irrigations that the triennial rotation derives the four agents which it exports under the form of grain, and to obtain them it is obliged to devote one-third of the farm to pasture. Fallow and pasture, then, are the plagues of the trien- nial system. Agriculture has for a long time endeavored to es- cape from fallowing. It has succeeded by introducing clover and similar plants into the rotation. In this manner the rotation is extended to five years. The crops of clover and roots have nourished the cattle, and the system has sufficed for itself. Here, also, are the data to which it gives rise. CD CO CO « ,_, © ,_, © is i OS © o ^ CO © © -f i-l HO 1—1 *~ CM © © 8 i • CM «# s 1 1 £ /— A««^ S— , ^-~ "N s~~^-~~ . -w^~, ■* HH rH rH CO CO ^ s 1-H CO 1-1 Tj( rH us © no CO © 1— CM *« CO o CO rH *- © © o © o U0 1-H •«* CO **< CM S « S3 O co iC CO CO uO »o ^ © J" CO o t-H O CO ft © os © O Ph !>. CO im' OS CM rH © rH f"H CO CM CO 1-H -# O CO o co « os CM tO © © o © CM CO *-» CO © »n> 3 <5 co co T* "# 00 js tj CM & 1 £ ^— ^-^v ^—-^-*s /-~^-«-x 2 ^ •* CO © IN © CM £ CO o to co rt* r}i CM rl CO r-t rH CO © 1-1 CO CO MB ■«*» © o rH t^ co CO to" o *t O A r-t CO Jt- CO • CO CM £ CO © iO rH Jt- CM lO 1-H CM <* CO CO ift ^ co ■^ © & CO CD co iO © CO lO © 5 *« •* CO CM IQ -* © .co *~ CO © r4 ■a ©' CM rH ts ,3 /-»-^-~s ,— ~*— -n /— ^^-^ CO CM rH .2 CO CO © CO © r-t cm co c © U5 © © © o> o OS i- CO CM CD rH CO CO 1-H cm" CO* 1 CO Jb- cm l-H CM CO © yt s £ 3 g .2 * 3 «* m : h 1 O Is 0) 'J "3 2 CO © to '■*; CB O rl CO 2 ® "8 Oh s s 1 1 H 1 -— H « 1 3 _y s '5 1 >H " efc H — fa 92 The triennial system accumulates important quanti- ties of alkalies and lime in the soil as pure loss. But through the clover and the roots, which have a marked preference for these elements, they are in great mea- sure turned to account. But the greatest advantage of the five year rotation consists in its influence with re- gard to nitrogen. You see that the cost of this ele- ment was repaid in benefiting the crops, and if you seek the plant to which this benefit is due, you will find that it is the clover, to the vegetable that forms part of the system. You will remember that, while the cereals draw the greater part of their nitrogen from the soil, vegetables, on the contrary, obtain it from the atmosphere. Thus you perceive, that the crop of wheat which follows the clover is more abundant, and contains more nitrogen, than that which preceded it — which proves that the clover has not impoverished the sail of that element. The five years' rotation, therefore, realizes the con- tinuous culture. It has two important advantages over the preceding. 1. It derives a portion of the nitrogen of the crops from the atmosphere. 2. It turns to ac- count the excess of potassa and lime brought by the manure. And the crops are also more abundant, as is shown by the following table. 93 MEAN ANNUAL RETURN OF THE TWO SYSTEMS. Triennial. Quinquennial, lbs. lbs. Weight of dried crop, per acre 2455 3131 Nitrogen contained in this crop 25 44 With the five years' rotation, agriculture has been brought to substitute the exportation of meat for that of the cereals, and it has derived decided advantages from the substitution ; for the sale of the cereals causes a loss of potassa, phosphoric acid and nitrogen to the farms, which cannot be compensated for except by a supply of manure, or by irrigation. If, on the contra- ry, the crops are consumed on the farm by the animals, we find in their excrements almost the whole of the phosphoric acid and potash contained in their food. The quantities that fix themselves in their tissues and bony structure, constitutes but a small loss. As to the nitrogen, their respiration rejects about a third of it into the atmosphere, in the gaseous state ; the other two-thirds return to the soil in the manure. This would be a loss, inevitably impoverishing the farm, without the clover, which derives an equivalent quan- tity from the atmosphere. It follows, from this, that the raising of cattle results in preserving to the soil almost the whole of the four agents which assures its fertility, and of procuring ben- efits in money without sensibly impoverishing the farm. 94 You see that the five years' system no more opposes our conclusions than the triennial j they receive, on the contrary, an unexpected light, and consequently af- ford them a striking confirmation. But, you will ask, is this the best practice devised ? No, Gentlemen. There exists a cultivation which re- alizes considerable profits, and which, when well carried out, causes almost no loss at all to the soil — that is the manufacturing cultivation of beetroot. In this case the exports are sugar or alcohol, substances ex- clusively composed of carbon, oxygen, and hydrogen, derived from water and the atmosphere. The ex- pressed pulp serves to nourish the cattle, and almost the whole of the useful elements are returned to the soil, especially if care be taken to mix the residue of distillation with the manure, instead of extracting the potash. Such are the systems of agriculture, developed dur- ing ages of groupings, true arc of promise to agricul- ture, in which it had been rash to make the least at- tack. Now we see them brought to rational and posi- tive notions, and science, which has learned to unveil the mysteries of their success, will learn also to give them the last improvement of which they are suscepti- ble. Without quitting the ways of the past, it will point out a simpler and more perfect method, which will be the ideal realization of the principle to which practical agriculture has always instinctively endeav- ored to conform itself, and constantly approached, and which we can now formularize in few words. 95 Cultivate the soil, and realize its profits, without impoverishing it of the four agents which assure its fertility. In all the systems I have described, and even in the case of beetroot, the farm always loses the nitrogen which the animal dissipates in the elementary state, and the universal salts contained in the cattle exported. A system, from which these losses were banished, would be the crown of the old method. It is colza that furnishes it. Its seed contains oil, a product of great value, and, like sugar, composed of carbon, oxygen, and hydrogen. Imagine an estate exclusively devoted to the cultiva- tion of colza, and that an oil-mill is attached to it. The oil will be exported, and will yield returns in cash ; all the rest, stems and oil-cake, will be returned to the soil without even passing through the medium of cattle. To this end we must add to the extraction of soil by pressure, a supplementary extraction by solution. The oil-cake, upon being removed from the hydraulic press, still contains 14 per 100 of oil, and sells at 6s. Gd. the cwt. The oil alone which they contain possesses this value. The substance of the oil-cake is thus gratuitously lost to the farm. When the oil is extracted by an appropriate solvent, sulphide of carbon, for example, in closed apparatus, constructed in such manner that a small quantity of this liquid put in circulation may exhaust considerable masses of it, there will remain a dry and pulverulent oil-cake, 96 containing all the products extracted from the soil. They are mixed with the stems on the dungbeap, and water is added. Putrefaction soon sets in, and we ob- tain an excellent manure, which restores to the soil the whole of the elements which the crops had re- moved from it, and which received the benefit of all the nitrogen derived from the atmosphere. After having discovered by what series of compen- sations the practice of the past arrived at conforming to the superior laws of vegetable production — laws of which it knew nothing — science may even imagine a simpler system, from which animals, and the loss they cause, are excluded, and which, yielding important profits, while enriching the soil, presents itself as the last degree of perfection to which it is possible to arrive by the methods of the past. But the fertility of the principles I have explained do not stop there. We must now abolish the practices pointed out to you, and replace them by a simpler agri- culture, more mistress of itself, and more remunerative. Instead of compelling ourselves by infinite cares and precautions to maintain the fertility of the soil, we re- constitute it, in every respect, by means of the four agents which I have pointed out, and which we can derive from the great stores of nature. Then no rota- tion of crops is necessary, no cattle, no particular choice in cultivation. We produce at will, sugar or oil, meat or bread, according as it best serves our interest. We export without the least fear the whole of the products 97 of our fields, if we see our advantage in so doing. We cultivate the same plant upon the same soil, in- definitely, if we find a good market for the produce. In a word, the soil is to us in future merely a medium of production, in which we convert at pleasure the four agents in the formation of vegetables into this or that crop which it suits us to produce. We are restrained only by a single necessity : to maintain at the disposal of our crops these four elements in sufficient propor- tion, so that they may always obtain the quantity their organization demands. Let us see to what point this condition is fulfilled in our new methods. To this end, it will be sufficient to compare the composition of the crops obtained from the farm at Vincennes with that of a complete 98 CO o CO CD 5 O C8 CO . 2 . 00 us oo C & O w « a> a 00 i» »o e 1 CD 1 15 3 CD CO -1 1~- fg3 «" • cs (M 1-1 CD a 5 O 2 S"S m CO s . o ,© 00 CM O e 3 O 1 CD 08 00 © —« CO CO £~ T-l a 3 i>- cS 5 © ■ o S » 1 • CO Ci CM C ) O 5 « » ■§ "S oo" W lO -H O CD 00 r-t You perceive, Gentlemen, that our new system satis- fies the law of equilibrium as well as the systems of the past : only, we hold the balance in our hands, and in proportion as one of the scales tends to rise, we restore the equilibrium by loading the other with an equal weight. 99 In the old systems, in which we maintained the equilibrium blindly, it frequently happened that one of the useful elements partially failed, and that the crops were also deficient. With the new processes, the plants, finding in abundance all they require, always attain their maximum of possible development; the crops are also much more abundant, as may be seen by the following table. POWER OF THE PRODUCTION OF THE OLD PRO- CESSES OF CULTIVATION COMPARED WITH THOSE OF THE NEW SYSTEM. Yield per Acre. Old Processes. New Processes. ( Straw. ..8.250) Straw 15 . 270 ) Wheats > 11.889 > 23.520 ! ( Grain. . . 3 . 639 ) Grain 8.250 j i Straw. . . 5 . 414 ) Straw 10 . 014 ) Peas \ > 7.610 > 12.863 (Grain... 2. 196) Grain 2.849) Beetroot Roots 6.978 Roots 20.110 But it is not sufficient to indicate the means of producing abundant crops j we must also show the method to be followed in order to obtain them econo- mically. The application of complete manures creates fertility everywhere ; but it is not everywhere nor always neces- sary to have recourse to so expensive a compound. When we suppress any of the constituent agents — the nitrogenous matters, for example — the yield of 100 wheat immediately undergoes a considerable reduction, but that of peas and vegetables is not affected by it. Suppress, on the contrary, the potassa : then the yield of the vegetables suffers most. For farnips, parsnips, and roots generally, it is the suppression of phosphate of lime which produces the worst effects. These results lead us to admit that among the four agents in each kind of crop there is one which exercises a more par- ticular influence upon the yield. We therefore formularize the following law, which will regulate the new agricultural practice. Although the presence of the four agents of fertility in the soil is necessary and indispensable for all plants, the exigencies of various cultivations are not the same with regard to the quantities of each of these agents — or in other words, each crop has its leading one. Thus, nitrogenous matter is the dominant agent for wheat and beetroots, potash for vegetables,, phosphate of lime for roots, &c. Suppose we undertake the cultivation of a piece of poor land. We begin by giving it the complete ma- nure, in order to create a sufficient provision of the four agents of fertility. We raise one or two crops of cereals upon this manure : then we continue the culture by giving to the soil, each year, the dominant element of the crop we propose to raise. If we adopt a rotation of four years with such crops that, at the end, has received the four agents, we can continue thus indefinitely without ever requiring the 101 complete manure. The same system is applicable to a fertile soil ; only we may dispense with the first dose of complete manure, and commence immediately by the dominant element of the first crop we desire to raise. If, on the contrary, it be desired to continue the same crop indefinitely, we content ourselves generally with the employment of its dominant ; but taking care to resume the application of the complete manure, imme- diately that a slight reduction in the weight of the crop points out the necessity for so doing. By these simple combinations we are in possession of a new agriculture, immeasurably more powerful than its predecessor. Formerly, the total matter placed by nature at the disposal of organized beings like ourselves, had its limits. All that the systems in vogue could do, was to maintain it ; but none succeeded in increasing it. With regard to the problems of life and population, human power encounters an impassable limit. The new processes of cultivation will have the effect of sup- pressing this barrier. Under their influences matters at present without value, which scarcely serve as mate- rials of construction, and of which nature possesses inexhaustible stores, can be converted into vegetable products : — forage to nourish the animals upon which we feed ; and cereals, to produce bread, the most valu- able of our resources. From this, the great stream of organized matter which sustains every existence will be increased with new waves, and the level of life will 102 continue unceasingly to rise to the surface of the globe. But, Gentlemen, beneath these great results which present themselves to the philosophic mind, there are others, more immediate, more practical — if I may so express myself, — which the system I strive to make prevail also carries on its flanks. Since the Revolution of 1789, the territory of France has continually been parcelled out in smaller portions. This fact has often been proclaimed ; but the evil still continues unremedied. According to official returns, the superficial area of France is now divided as follows : — Nature of the Property. Mean Extent. Surface occupied. Corresponding Population. Acres. Acres. Large Estates 415 43,320,000 1,000,000 Medium Estates. . . . 87.50 19,250,000 1,000,000 Small Estates 35 16,800,000 2,400,000 Very small Estates. . Totals 8.62 36,130,000 19,500,000 115,500,000 24,000,000 Of the one hundred and fifteen millions of acres of cultivated land, there are thirty-six millions possessed by proprietors whose estates do not exceed eight and a half acres in extent. What kind of agricultural sys- 103 tern can a man pursue who possesses only eight acres for every thing, and who requires as much for the sup- port of his family ? How, and with what, will he obtain manure ? He can have neither meadows nor cattle. He must necessarily farm badly; his land is fatally condemned to sterility, and himself to poverty. To combine the agents of fertility which have re- posed in geological strata since the foundations of the earth were laid, to place them at the disposal of the small farmer, will be to give fertility to fifty millions of acres devoted to the small and minimum cultivation, and create prosperity among twenty out of the twenty- four millions occupied in agricultural industry. Now I ask you, Gentlemen, if these views are not superior to the finest dreams of charity and philan- thropy ? Would they not also, if they were merely in the condition of scientific conceptions, suftice to excite our zeal ? But experience has returned its verdict. The crops you have before your eyes prove that with a manure, averaging in cost about five pounds a year, it is possible to obtain abundant harvests. Reduce, if you will, the excess of production, per acre, to a ton, which is here raised above three tons ; and applying this data to the fifty millions of badly cultivated acres, and see to what financial results we shall be inevit- ably led. The first movement in this direction will create a demand for fertilizing materials to the extent of some millions. What an impulse this must give to com- merce ! 104 Next to obtain twenty millions of tons more wheat than French agriculture supplies at the present time, and consequently an increase of wealth of about five millions sterling. What a guaranty against famine ! What is required to accomplish such a revolution ? We must apply the principles I have explained to you, and generalize them. In the second place, commerce must place the agents of fertility under the protection of new institutions of credit. They must be so conceived that the advances for the necessary manures may be made to the small farmer, to be repaid out of the ex- cess of crops derived from the fertilizers. The solution of this problem connects itself in a sin- gular manner with social and political destinies. Every- where the approach of democracy manifests itself. Is this a good ? Is it an evil ? I am not competent to de- cide the question : but it is very certain that at the present time the greater part of agricultural population deserts the country to seek an easier condition of life in the cities. This immense class, second only to the working pop- ulation of the cities, represents, in a high degree, the true public spirit. To change its economic situation, to put it into a condition of more intensive cultivation, notwithstanding the exigences of the scale upon which it operates, is to attach it tp the soil by its own interests. By this means a large conservative party may be created, with- out which a democracy based upon commerce will grow 105 up, leading only to a crisis analagous to that which now presents so deplorable a spectacle in America. England has avoided this danger at the price of an enlightened and patriotic aristocracy, but whose exist- ence perpetuates an inequality in human destinies which conscience repudiates and the laws of humanity condemn. Neither England nor America, therefore, have solved the problem of a powerful, wise, and just democracy. To me, it seems that our beautiful country is pre- destined to give this great example to the rest of the world, and I have the firm hope that the principles I have placed before you, in the course of these lectures, will serve as the starting point to the realization of this inestimable result. APPENDIX, EXPERIMENTAL FARM AT VINCENNES. HARVEST OF 1864. On the 31st of July, M. George Ville reaped and thrashed his crops in presence of a large concourse of agriculturists. The results were as follows: — Wheat: — Third Crop from the same land without fresh manure since the first application. Crop per Acre. Without Manure. With Complete Manure. Straw 704 lbs 5.913 lbs. Grain 193 "..... 2.464 " Total . . . 0.897 lbs 8.377 lbs. Wheat : — Fourth Crop without Fresh Manure since the first. Crop per Acre. Without Manure. With Complete Manure. Straw 1.074 lbs 4.629 lbs. Grain 316 " 1.760 " Total . . . 1.390 lbs 6.389 lbs. Colza : — Coming after two Crops of Barley without fresh Manure. Crop per Acre. Without Manure. With Complete Manure. Straw and Silicates . 5.632 lbs 7.700 lbs. Grain 1.320 " 2.410 " Total . . . 6.952 lbs 10.110 lbs. 107 CROPS OF 1864. — BEETROOT. On the 30th of October the crop of Beetroots was publicly got in. The results obtained were as fol- low: — .. Soil without Manure. Crop per Acre. Leaves 6.204 lbs. . 16.544 " Total .... . 22.748 lbs. This piece of land, put under cultivation in 1861, had previously yielded two crops. In 1861. In 1S62. Crop per Acre. Leaves .... 14.696 lbs Leaves .... 7.040 lbs. Roots .... 44.616 " Roots .... 12.056 " 59.312 lbs. 19.096 lbs. In 1863 the crops were devoured by the white worm, consequently there was no return, and this year's crop was a little increased by the preceding year being fallow : — 2. Soil with Complete Manure. Crop per Acre. Leaves 6.618 lbs. Roots 24.990 " 31.608 lbs. This piece of land, like the preceding, had furnished two previous crops since ir received any manure. 108 In 1861. In 1862. Crop per Acre. Leaves .... 14.344 lbs. Leaves .... 9.680 lbs. Boots .... 47.960 " Roots .... 21.820 " 62.304 lbs. 31.500 lbs. 3. Land with Complete Manure, but which has received acid phosphate of lime instead of ordinary phosphate. Leaves 7.700 lbs. Roots 30.624 " 38.324 lbs. This piece of land had also yielded two crops previous, since it had received any manure. In 1861. In 1862. Crop per Acre. Leaves .... 15.488 lbs. Leaves .... 11.000 lbs. Roots .... 78.786 " Roots .... 33.968 " 94.275 lbs. 44.968 lbs. 4. Land with Complete Manure. — Crop of Beetroot coining after three fine crops of Wheat without fresh manure. Crop per Acre. Leaves 7.304 lbs. Roots 36.826 " 44.130 lbs. LIBRARY OF CONGRESS D00E7fl0700fl ;v- ^