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i:ja3i:iA.'Bir of tii^ 
 
 Massaclnasetts ' 
 
 OCT 22 1910 
 
 ^gric^iltural 
 College 
 
 SOIU INVESTIGAXIOrsl3. 
 
 MILTON WHITN-EY. 
 
 (^Extracted from the Fourth Annual Jleport,) 
 
 Maryland Ageicultueal Experiment Station. 
 

EEPOET OF THE PHYSICIST. 
 
 By Prof. Milton Whitney. 
 
 SOIL INVESTIGATIONS. 
 
 Introduction. 
 
 It is proposed at this time to give a brief account of the soil 
 investigations carried on by the Station and attempt to point out 
 the application of the results and conclusions to the explanation and 
 solution of problems in practical agriculture. 
 
 We are glad to report that the U. S. Government has taken up 
 this work, and, through the Weather Bureau of the Department of 
 Agriculture, has placed a sum of money at our disposal to enable us 
 to complete some work on hand in order to prepare a full report or 
 monograph, to be ready for publicaLtioli'" *by' liext July. In view of 
 the fact that the report to be issued by the Government will of neces- 
 sity be much fuller and more exhaustive than this can be. and will con- 
 tain a detailed description of the methods, formulae and data upon 
 which our lines of reasoning are based, we will introduce into this 
 report only such statistical and other data as will make the narrative 
 complete — referring all who wish to follow the subject more closely 
 and in further detail to the Government report. 
 
 It has taken six years of constant application, observation and 
 study, in the Held, plant house and laboratory, to gain a clear idea 
 of the nature and structure of the soil in its relation to meteorology 
 and agriculture. When, in the fall of 1890, the work was com- 
 menced here in its application to the soils of Maryland, several fun- 
 damental principles of soil physics still remained to be worked out. 
 This required the use of very expensive apparatus, only to be found 
 in a well-equipped physical laboratory. It was essential, also, that 
 the work be based upon the most thorough geological data to show 
 the area and distribution of the different soil formations. There wa& 
 no reliable geological map of the State, and the Director of the U. S. 
 Geological Survey stated that the Professors of Geology of the Johns 
 Hopkins University had all the available data, and were themselves 
 
250 MARYLAND AGRICULTURAL 
 
 working out in more detail tlie geology of Maryland, and advised a 
 co-operation with thein in this soil work. 
 
 The work of this division of the Experiment Station on tlie inves- 
 tigation of soils was, therefore, located at the Johns Hopkins Uni- 
 versity. By permission of the Trustees of the University the work 
 was moved in June to their large estate of Clifton, on the Harford 
 Road, where it is at present being carried on. The reasons for this 
 and our relations with the University are more fully set forth in tlie 
 Director's report. 
 
 The President of the University and the Professors in the Depart- 
 ments of Chemistry, Geology and Physics have shown, from the 
 first, an interest in the work and a cordial spirit of co-operation, with 
 :a desire to have us make a practical application of their work and 
 information. 
 
 Argument. 
 
 It takes really very little experience for one to judge at a glance 
 whether a soil is suited to grass or wheat or to-bacco or watermelons, 
 and he has but to turn up a small handfuU of earth to see if the soil 
 is in o-ood condition, as regards moisture, for the growing crops. And 
 yet, agricultural chemists have worked over this problem for years, 
 argning points from minute difierences in chemical composition of 
 the soils or plants, which their most refined methods make none too 
 sure, overlooking the fact that the farmer can tell from the a'piiear- 
 ance whether a soil is in "good heart" and what it is best fitted to 
 grow. The farmer cannot see these minute differences in chemical 
 composition. He judges from the general appearance of the land, 
 the physical structure of tlie soil. 
 
 Those of us who are engaged in agricultural investigations, even in 
 soil studies, are not as far advanced as the farmer in our knowledge 
 of the soil, nor will we be until we can understand and explain these 
 visible signs upon which he bases his judgment. He has kept up 
 with Qur work on the chemical composition of soils and has applied it 
 and made it his own. But he goes further than we have gone, for he 
 can tell, as no chemical means will enable us to judge, whether the 
 land is in good condition, is fertile, has body and will hold manures, 
 is strong or will shortly run out, is dry and leachy or retentive of 
 moisture. He can tell what class of plants it will best produce. In 
 this lies the key to all soil investigations. Chemical analysis has its 
 
EXPERIMENT STATION. 251 
 
 part to plaj, but we have yet to get the key to the interpretation of 
 its results. And this key is to be found in the study of the physical 
 structure of the soil and the physical relation to meteorology and to 
 plant growth. Meteorology has not done, and is not doing, its best 
 good for agriculture. While we admit it is very important to have 
 the rainfall data furnished by the Weather Bureau, still, as the rain 
 does not benefit the crops until it enters the soil, it is very essential 
 that the rainfall be studied below, as well as above, the surface of the 
 ground. 
 
 Crop production is not directly limited by the amount of rainfall, 
 but by the moisture in the soil. Six inches of rainfall a month may 
 mean a good season, or, with this same amount differently distributed 
 throughout the month, the crops may be injured by excessive wet or 
 by prolonged drought. Changing seasons of wet or dry, hot or cold, 
 have far more effect on the crops than any combination of manures. 
 
 There is a certain type of land in this State, in a certain geological 
 formation, which is left out in pine barrens as it is too poor to put 
 under cultivation ; another type, in a different geological formatian, is 
 well suited to melons and garden truck ; still other types, to tobacco, 
 wheat and grass. This is not a rnatter of mere plant food. ISo addi- 
 tion of any amount or any combination of available plant food will 
 at once enable a good wheat crop to be produced on the soil of the 
 pine barrens, or on the light truck lands. It is a matter of available 
 water rather than of available plant food, and if after some years the 
 light land is brought up to produce good yields of wheat, the whole 
 appearance and structure of the soil will be found to have changed, 
 and with it, the relation of the soil to the movement of water — to the 
 movement of the rainfall after it enters the soil. 
 
 And so in the deterioration of land, in the deterioration of our 
 tobacco and wheat lands. It is not due to loss of plant food so much as 
 to the causes which change the whole appearance of the soil to the 
 eye — a change of the physical structure of the soil, a change in the 
 relation of the soil to the movement or circulation of water. 
 
 Our work, then, is on the physical structure of the soil and its re- 
 lation to the circulation of water — the movement of the rainfall after 
 it enters the soil, and the physical effect of fertilizers and manures 
 thereon, as related to crop production. 
 
252 maryland agricultural 
 
 Summary of the Results. 
 
 This report will treat lirst of tlie underlying principles governing 
 the circulation of water in the soil, then of the different soil types 
 found in the State, of their structure and relation to the circulation 
 of water, leading up to the application of these principles in a dis- 
 cussion of the improvement of lands. A summary will be given 
 here, outlining the body of the report, so that it may be followed 
 more easily. 
 
 I. The circulation of water in the soil. 
 
 a. Due to gravity or the weight of water acting with a constant 
 force to pull the water downward, and also, to surface tension or the 
 contracting power of the free snrface of water, (water-air surface,) 
 which tends to move the water either up or down or in any direction, 
 according to circumstances. 
 
 h. The ordinary manures and fertilizing materials change the sur- 
 face tension or pulling power of water. 
 
 II. The effect of fertilizers on the texture of the soil. 
 
 a. There is a large amount of space between the grains in all soils 
 in which water may be held. The rate of movement of the water 
 will depend : 1. Upon how much space there is. 2. Upon how 
 this is divided up, i. e. upon how many grains there are per unit 
 volume of soil. 3. Upon the arrangement of the grains of sand and clay. 
 
 h. Flocculation — a phenomenon of great importance in agricul- 
 ture — changing the arrangement of the grains and consequently the 
 texture of the soil. 
 
 III. The volume of empty space in soils. 
 
 lY. The relation of geology to agriculture. 
 Y. Soil types. 
 
 a. Reasons for establishing soil tj'pes. 
 
 h. The very evident difference in texture is the probable cause of 
 the difference in relation to plant growth and to local distribution of 
 crops. 
 
 c. Soil types in Maryland and the samples from which they are 
 made. 
 
 YI. Mechanical analysis of the type soils. 
 
EXPERIMENT STATION. 253 
 
 YII. Approximate number of grains per gram of soil. 
 
 YIII. Approximate extent of surface area per cubic foot of soil. 
 
 IX. The circulation of water in these type soils. 
 
 a. The relative rate of circulation of water in soils short of satura- 
 tion is very different in these type soils and probably explains the 
 difference in relation to crop production. 
 
 h. The relative rate of circulation of water in these soils when 
 fully saturated. 
 
 G. The influence of the total volume of space. 
 
 d. The rate of circulation of water is relatively faster in light 
 sandy lands, when far short of saturation, than in heavier clay lands, 
 but it may be far slower in these same light lands when fully satu- 
 rated, owing to the less amount of space in the soil. 
 
 X. The improvement of soils. 
 
 a. In soils having as much clay as the type requires, the grains 
 of clay may be rearranged by causing flocculation, or the reverse, by 
 the use of ordinary fertilizing materials. 
 
 h. In soils having less clay than the type : 1. The grains may 
 still be rearranged, or, 2. organic matter may be precipitated from 
 solution within the soil, in light, flocculent masses, with lime, acid 
 phosphate, or the proper mineral manures, or constituent of the soil 
 itself, and so fill up the spaces and retard the rate of circulation of 
 the water. 
 
 I. The Circulation of Water in the Soil. 
 
 The motive power, which causes water to move from place 
 to place within the soil, consists of two forces : gravity, or the 
 weight of the water itself, and surface tension. Gravity tends 
 to pull the water downward, and acts with a constant force per 
 unit mass of water. Surface tension, or the contracting power 
 of any exposed water-surface, may move the water in any direc- 
 tion within the soil, according to circumstances. It may act, there- 
 fore, loith gravity to pull the water down, or against gravity to pull 
 it up. This has an important practical bearing on the movement of 
 water in sandy lands, as we shall show in speaking of the applica- 
 tion of these principles to our type soils. 
 
254 MARYLAND AGRICULTUKAL 
 
 The force of gravity need not be further considered here. 
 
 Surface tension is tlie tendency which any exposed surface has 
 to contract to the smallest possible area, consistent with the weight of 
 the substance. If a mass of water is divided, or cleft in two, leaving 
 two surfaces exposed to the air, the particles of water on either sur- 
 face, which were before in the interior of the mass and attracted 
 from all sides by like particles of M^ater, have now water particles on 
 only one side to attract them, with only a few air particles, compara- 
 tively very far apart, on the other side, where formerly was a com- 
 pact mass of water. All the surface particles of water will therefore 
 be pulled from within the mass of water, and the surface will tend to 
 contract as much as possible, leaving exposed the smallest number of 
 surface particles, and causing a continual strain or surface tension. 
 On any exposed water-surface, there is always this strain or tension, 
 ready to contract the surface, when it may. 
 
 It is a constant, definite force per foot of surface, for any sub- 
 stance at a given temperature. In the case of liquids and solutions, 
 in which we are most interested, it varies with the nature of the 
 liquid and the substance in solution. 
 
 This is surface tension ; and we have it in the soil as a strain or 
 tension along the free surface of water within the soil, which tends 
 to contract the surface and so move the water from one place to an- 
 other as it is needed. 
 
 There is, on the average, about 50 per cent, by volume of space 
 within the soil which contains no solid matter, but only air and water. 
 This we shall call empty space. In a cubic foot of soil there is about 
 half a cubic foot of empty space, but this is so divided up by the 
 very large number of soil grains that the spaces between the grains 
 are extremely small. 
 
 When a soil is only slightly moist the water clings to the soil 
 grains in a thin film. It is like a soap bubble with a grain of sand or 
 clay inside," instead of being filled with air. Where the grains come 
 together the films are united into a continuous film of water through- 
 out the soil, having one surface against the soil grains and the other 
 exposed to the air in the soil. As the soil grains are surrounded by 
 this elastic film, the tension on the exposed surface of the water will 
 support a considerable weight, for the soil grains, thus enveloped, are 
 extremely small and have many points of contact around which the 
 film is thicker and is held with greater force. 
 
EXPERIMENT STATION. 255 
 
 If more water enters the soil the film thickens, and there is less ex- 
 posed water-surface. If the empty space is completely filled with 
 water there will be none of this exposed water-surface, and therefore, 
 no surface tension. Gravity alone will act and with its greatest 
 force. If the soil is nearly dry, there will be a great deal of this ex- 
 posed water-sarface, a great amount of surface tension, and with so 
 little water present, gravity will have its least effect. 
 
 The grains in a cubic foot of soil have, on the average, no less than 
 50,000 square feet of surface area. There is less, of course, in a light 
 sandy soil, and more than this in a clay soil. If there is only a very 
 small amount of water in the soil the film of water around the grains 
 will be very thin, and there will be nearly as much exposed water- 
 surface as the surface area of the grains themselves. If a cubic foot 
 of soil, thus slightly moistened, and having this large extent of exposed 
 water-surface, be brought in contact with a body of soil fully saturated 
 with water, in which there is none of this water-surface, the water- 
 surface in the drier soil will contract, the film of water around the 
 grains will thicken and water will be drawn from the wet into the 
 dry soil, whether it be to move it up or down, until, neglecting 
 gravity or the weight of water itself, there is the same amount of 
 water in the one cubic foot of soil as in the other. When equilibrium 
 is established there will be the same extent of exposed water-surface 
 in these two bodies of soils. 
 
 When water is removed from a soil by evaporation or by plants, 
 the area of this exposed water-surface is increased, and the tension 
 tends to contract the surface and pull more water to the spot. 
 
 When rain falls on rather a dry soil, the area of the exposed water- 
 surface in the soil is diminished, and the greater extent of water-sur- 
 face below contracts and acts, with gravity, to pull the water down. 
 
 By numerous careful and verified experiments, we have found that 
 fertilizers change this surface tension and modify the contracting 
 power of the free surface of water to a remarkable degree, and so 
 modify thepower which moves water from place to place in the soil. 
 
 The following table gives the surface tension of a solution in water 
 of several of the ordinary fertilizing materials. This list is not com- 
 plete, and the solutions used were of any convenient strength. The 
 results are preliminary to give material for more thorough and de- 
 tailed investigation. The surface tension is expressed in gram-meters 
 
256 MARYLAND AGRICULTURAL 
 
 per square meter, that is, on a square meter (or yard) of liquid sur- 
 face there is safiicient energy to raise so many grams to the height of 
 one meter (yard.) 
 
 Table 1 : — The Surface Tension of Various Solutions. 
 
 {Gram-meters per square meter ^ 
 Solution of Sp. ge. * Mean. Highest. Lowest. 
 
 Salt 1.070 6 T.975 8.126 7.796 
 
 Kainit 1.053 6 7.900 7.993 7.805 
 
 Lime 1.002 4 7.696 7.750 7.674 
 
 Water 1.000 18 7.668 7.923 7.506 
 
 Acid Phos 1.005 4 7.656 7.800 7.563 
 
 Plaster 1.000 9 7.638 7.730 7.572 
 
 Soil extract 1.000 5 7.089 7.166 6.969 
 
 Ammonia 0.960 6 6.869 6.950 6.826 
 
 Urine 1.026 10 6.615 6.740 6.471 
 
 * Number of measurements from which the mean is taken. 
 
 "Wullner gives the following :* 
 
 Sp. ge. Tension. 
 
 Water 1.000 7.666 
 
 Sulphuric acid 1.849 6.333 
 
 " " 1.522 7.610 
 
 '■ - 1.127 7.556 
 
 Hydrochloric acid .... 1.153 7.149 
 
 Nftric acid 1.500 4.275 
 
 " 1.270 6.768 
 
 " 1.117 7.09S 
 
 Salt • 1.200 8.400 
 
 Nitrate of potash 1.137 7.276 
 
 *Lehrbuch der Experimental Physik, Vol. I., p. 341. 
 
EXPERIMENT STATION. 257 
 
 The soil extract was made by shaking up a little soil with just 
 sufficient water to cover it; the water was afterwards filtered off and 
 used for the determination. It will be seen from the table that this 
 contact with the soil reduced the surface tension of water very 
 considerably. There is little doubt that the surface tension of soil 
 moisture is very low, much lower than that of pure water. Salt and 
 kainit, on the other hand, increase the surface tension of water very 
 considerably and raise it far above that of the soil extract. This 
 probably explains the fact, which has been often commented on, that 
 an application of salt or kainit tends to keep the soil more moist. 
 This has often been remarked in connection with the application to a 
 clover sod. By increasing the surface tension of the soil moisture 
 they increase the power the soil has of drawing water up from below 
 in a dry season. 
 
 Ammonia and urine lowered the surface tension of water con- 
 siderably below that of the soil extract, and far below that of pure 
 water. This, probably, also explains a matter of common observa- 
 tion, that the injudicious use of excessive quantities of organic matter 
 is liable to "burn out" a soil in a dry season, because by reducing the 
 surface tension, water can less readily be drawn up from below. 
 
 This opens up a field of investigation on the determination of the 
 surface tension of the moisture in various soils, and a more extensive 
 and more systematic study of the effect of various fertilizing mate- 
 rials on the surface tension of water and soil extract, and it opens up 
 a wide field in its application to practical agriculture and the use of 
 manures and fertilizers. 
 
 This effect of fertilizins; materials in chansfino- the surface tension 
 of a liquid, and thereby changing the force or power which moves 
 water from place to place in the soil, is only a first eiTect, as the con- 
 tinued use of these fertilizing materials may change the texture of 
 the soil itself and the relation of tlie soil to the circulation of M'ater. 
 
 II. The Effect of Fertilizers on the Texture of the Soil. 
 
 Surface tension may be expressed in another way. The 2?otential 
 of a single water particle is the force which would be required to pull 
 it away from the surrounding water particles and remove it beyond 
 their sphere of attraction. For simplicity, it may be described as the 
 total force of attraction between a single particle and all other 
 particles which surround it. With this definition it will be seen that 
 
258 MARYLAND AGKICULTUKAL 
 
 the potential of a particle on an exposed surface of water is only one- 
 half of the potential in the interior of the mass, as half of the 
 particles which formerly surrounded and attracted it were removed 
 when the other exposed surface of water was separated from it. A 
 particle on an exposed surface of water, being under a low potential, 
 will therefore tend to move in towards the center of the mass where 
 the potential, i. e., the total attraction, is greater, and the surface will 
 tend to contract so as to leave the fewest possible number of particles 
 on the surface. 
 
 If instead of air there is a solid substance in contact with the water 
 the potential Avill be greater than on an exposed surface of the 
 liquid, for the much greater number of solid particles will have a 
 greater attraction for the water particle than the air particles had. 
 They may have so great an attraction that the liquid particle on this 
 surface, separating tiie solid and liquid, may be under greater poten- 
 tial than prevails in the interior of the liquid mass. Then the surface 
 will tend to expand as much as possible for the particles in the 
 interior of the mass of liquid will try to get out onto the surface. 
 This is the reverse of surface tension. It is surface pressure, which 
 may exist on a surface separating a solid and liquid. 
 
 If two small grains of clay, suspended in water, come close 
 together, they rnay be attracted to each other or not, according to the 
 potential of the water particles on the surface of the clay. If the 
 potential of the surface particle of water is less than of a particle in 
 the interior of the mass of liquid, there will be surface tension and 
 the two grains will not come together because this would enlarge the 
 surface area and increase the number of surface particles in the liquid. 
 If, on tlie other hand, the potential of the particle on the surface of 
 the liquid is greater than the potential of a particle in the interior of 
 the liquid mass, the surface will tend to enlarge and the grains of 
 clay may come close together and be held there with some force, as 
 their close contact increases the number of surface particles in the 
 liquid around them. This probably explains the phenomenon of 
 tiocculation, a phenomenon of great importance in agriculture. 
 
 Muddy water may remain turbid for an indefinite time. If a trace 
 of lime or salt be added to the water the grains of clay focculate, 
 that is, they come together in loose, light iiocks, like curdled milk, 
 and settle quickly to the bottom, leaving the liquid above them clear. 
 Ammonia and some other substances tend to prevent this and to keep 
 
EXPERIMENT STATION. 25'D 
 
 the grains apart, or to push them apart if flocculation has already 
 taken place. This is similar to the precipitation of some solid 
 matters from solution. When lime is added to a filtered solution of 
 an extract of stable manure, the organic matter is precipitated in 
 similar loose, bulky masses. 
 
 It will be remembered that there is, on an average, about 50 per 
 cent, by volume of empty space in the soil. This empty space is 
 divided up by a vast number of grains of sand and clay. If these 
 grains are evenly distributed throughout the soil, so that the separate 
 spaces between the grains are of nearly uniform size, water will move 
 more slowly through the soil than if the grains of clay, through 
 flocculation, adhered closely together and to the larger grains of sand, 
 making some of the spaces larger and otliers exceedingly small. 
 
 We have, then, this principle to work on in the improvement of 
 soils. In a close, tight clay, through which water moves slowly, the 
 continued use of lime may cause flocculation, the grains of clay may 
 move closer together, leaving larger spaces for the water to move 
 through. On the other hand, there are soils in which the clay is held 
 so closely to the grains of sand as to give tlie soil all the appearance 
 and properties of a sandy soil, although there is as much clay present 
 as in many a distinctively " clay soil." 
 
 Again, in a light sandy land, lime may precipitate the organic 
 matter from solution within the soil, in light, bulky masses, which 
 will All up the spaces and retard the rate of circulation of water. 
 
 And so, if judiciously used, lime may be the "best fertilizer" for 
 a light sandy soil or for a heavy clay land. In the one case, there 
 must be sufhcient organic matter for the lime to act on or it will 
 injure the soil ; in the other case, there is no such need of organic matter 
 in liming a tight clay soil, and too much of it may be decidedly 
 injurious. 
 
 We will speak of this more at length when we come to speak of 
 the application of these principles to the improvement of soils. 
 
 III. The Volume of Empty Space in Soils. 
 
 There is, on the average, about 50 per cent, by volume of empty 
 space in the soil. The amount in the soil proper will vary with the 
 stage and state of cultivation, but the "empty space in the undisturbed 
 subsoil will remain fairly constant. The amount of space has not 
 been determined in the soils of Maryland, for the determination 
 
260 MARYLAND AGRICULTURAL 
 
 requires that an exact volume of soil be removed from the field, and 
 this takes much time and careful work. This will be made the 
 subject of some future investigation, and for the present our work 
 must be based upon determinations which have been made elsewhere. 
 The amount of space has been determined in a number of subsoils 
 in South Carolina, in their natural position in the field, taking in a 
 wide range of soil formations. The per cent, bj volume of empty 
 space is given in the table following. 
 
 Table 2: — Empty Space in So. Ca. Subsoils. 
 Per Cent, hy Volume. 
 
 78. Wedgefield, (sandy laud) 41.80 
 
 QQ. Gourdins 42.82 
 
 57. Sumter 44.10 
 
 80. Lesesne 46.41 
 
 57a. Sumter 47.70 
 
 69. Gourdins, (Mr. Roper) 49.74 
 
 64. Lanes 50.00 
 
 74. Wedgefield, ("Red Hill" formation) 50.03 
 
 69a. Gourdins 50.25 
 
 53. Charlotte, N. C 52.05 
 
 71. Gourdins, ("Bluff land") 55.40 
 
 53a. Charlotte, K C 57.19 
 
 76. Wedgefield, ("gummy land") 58.46 
 
 76a. Wedgefield, ("gummy land") 61.54 
 
 42. Chester, ("pipe clay") 05.12 
 
 The first six subsoils, which may be considered essentially sandy, 
 have, on the average, 45.43 per cent, by volume of empty space. 
 The remaining nine subsoils, which are from essentially clay lands, 
 have, on the average, 55.55 per cent, by volume of empty space. 
 
 In "How Crops Feed," Johnson gives the weight of a cubic foot 
 of sandy soil as 110 pounds, and of a cubic foot of a clay soil as 75 
 
EXPERIMENT STATION. 261 
 
 pounds. This would give about 34 and 55 per cent, by volume of 
 empty space, respectively, in these soils. 
 
 It is unfortunate that the term "light soil" has become commonly 
 applied to that which actually weighs a good deal more tlian an 
 equal bulk of what is called "heavy soil." 
 
 In our own work, unless the actual determinations have been 
 made, we have assumed that the subsoil of "light sandy land" has 
 45 per cent, by volume of empty space, and that of a strong clay 
 land, 55 per cent. If all the space within these soils was filled with 
 water, they would contain 22.41 and 31.55 per cent, hy weight of 
 water, respectively. 
 
 For the empty space in our soil types, to be presently desc ribed, 
 we have assigned, as probable, values based on this South Carolina 
 work. 
 
 lY. The Relation of Geology to Agkicultuke. 
 
 We shall use in this report certain geological names which may be 
 unfamiliar to many of our readers, and it seems well to insert a sec- 
 tion explaining the reason for this and the general relation of geology 
 to agriculture. 
 
 We shall show presently that there are well-marked types of soil in 
 tliis State ; some suited to grass and wheat, others to wheat but 
 rather light for grass, others to tobacco, truck, or left out as barren 
 wastes. The texture and general appearance of these soils differ very 
 much so that one can tell at a glance to what kind of crop each of 
 these types is best adapted. We shall show further, that from this differ- 
 ence in texture, which is so very apparent to the eye, there is a 
 marked difference in the relative rate with which water moves within 
 the soil, and the ease with which the proper amount of water may be 
 maintained and supplied to the crop. 
 
 As crops differ in the amount of water which they require, and in 
 the amount of moisture in the soil in which the}^ can best develop, 
 this difference in the relation of these soil types to water probably 
 accounts for the local distribution of plants. 
 
 In green-house culture the same kind of soil is used for all kinds of 
 plants, but great judgment is rec|uired in watering the plants. Some 
 plants require a very wet soil, others must be kept quite dry. The 
 amount of water required will not be the same at different stages of 
 development of the plant. During the earlier growing period the 
 
262 MARYLAND AGRICULTURAL 
 
 soil is kept quite wet, but during the fruiting or flowering period 
 the soil is kept much drier. Each class of plants requires in this 
 way special treatment, and it is through this judicious control of the 
 water supply in the soil and the temperature of the air, that the 
 best development of each class of plants is attained. 
 
 Our soil types, therefore, in having different relations to the circu- 
 lation of water, partake somewhat of these artificial conditions in 
 green-house culture, and on each of them certain classes of plants will 
 find conditions of moisture best suited to their growth and develop- 
 ment. 
 
 Our soils have been formed from the disintegration, or decay, of 
 rocks. The crystalline rocks, such as granite, gabbro and serpentine, 
 from which the soils of Northern Central Maryland are derived, have 
 been formed by the slow cooling of the earth's crust. They are 
 made up of different minerals, the most common of which are quartz, 
 feldspar and mica, cemented together usually with lime or silica. 
 The kind of rock is determined by the kind and relative amount of 
 each of these minerals of which it is made. When the rocks decay, 
 the cementing material is dissolved and carried off, and many of the 
 minerals themselves are changed. Now, the texture or the relative 
 amount of sand and clay contained in the soil resulting from the dis- 
 integration of these rocks, will depend upon the kind of rock, that is, 
 upon the minerals of which it was composed. 
 
 The material resulting from the disintegration of these rocks is 
 slowly washed away and carried off by streams and rivers. As the cur- 
 rent of water becomes slower near the sea, the sand is deposited along 
 a rather narrow shore line, while the finer particles of clay are carried 
 further and deposited over wider areas. The conditions where some 
 parts of this material are being deposited may be favorable to the 
 o-rowth of coral and of various kinds of shell-fish, so that their re- 
 mains accumulate in beds of great thickness, giving the material for 
 the limestone of the present day. These sediments are thus assorted 
 out by subsidence in water of different velocities, as though they had 
 been sifted and the different grades of material spread out over wide 
 areas. 
 
 The sediments, being slowly deposited in beds of great thickness, 
 are converted into rocks through the agency of heat and great 
 pressure to which they are subjected by the accumulation above, and 
 so sandstones, limestones and shales have been formed; the sandstone. 
 
EXPERIMENT STATION. 263 
 
 where the coarser material has been deposited near the shore ; the 
 limestone, where the shells have accumulated ; and the shale, where 
 the line nind has been spread out over a wider area of still water. 
 
 It is from the disintegration of these "sedimentary" rocks, as they 
 are called, which have since been raised above the surface of the 
 water, that the soils of Western Maryland have been formed. There 
 are the limestone valleys, where shell-fish were once abundant, and 
 Avhere now is a strong clay soil, well adapted to grass and wheat ; 
 the sandstone ridges, some of which, resisting decay, form the 
 mountain ranges, while others, made of finer grains of sand and less 
 firmly cemented together, form some of the fertile hill and valley 
 lands ; the shales, in which the grains of rand were so extremely 
 small that they adhere so closely to each other that tliey^ do not 
 thoroughly disintegrate, and the soil is filled with fragments of the 
 rock and supports but a scanty mountain pasture. 
 
 The soils of Southern Maryland and the Eastern Shore are of more 
 recent origin. The sediments have not, as yet, been subjected to the 
 great heat and pressure required in rock-making, and they are still 
 in the first stages of formation. 
 
 Now, geology defines the limits and areas of these different forma- 
 tions and of these different rocks, and, as I have shown, that these 
 rocks determine the texture of the soil, a thorough and detailed 
 geological map of the State should answer for a soil map. Any one 
 familiar with the texture of the soil, or kind of soil, formed by the 
 disintegration of granite, gabbro, and the different kinds of lime- 
 stones, sandstones and shales, should be able to tell by a glance at the 
 map the position and area of each kind of soil. Each color on 
 the map would represent a soil forma,tion of a certain texture, in 
 which the conditions of moisture, under our prevailing climatic con- 
 ditions, would be best adapted to a certain crop. 
 
 Such a geological or soil map would be of the greatest aid to any 
 one interested in the agricultural lands of the State. It seems to me 
 that such a map of the soil formations in this State would be of great 
 benefit to agriculture in the hands of farmers and of those interested 
 in immigration and in the material advancement of the agricultural 
 interests of the State. Kot only so, but I think the interest of this 
 work demands the most thorough and detailed geological survey so 
 that each of these soil formations may be carefully located and out- 
 lined. The wheat, tobacco, truck and barren lands of Southern 
 
264 MA.RYLAND AGRICULTURAL 
 
 Maryland are each confined to certain different geological formations 
 for their best development, and a geological map of this portion of the 
 State should show the area and distribution of the lands best adapted 
 to these crops. 
 
 There is usually some marked and distinctive botanical character 
 in the herbage of these different soil formations. We have pine 
 barrens, white oak lands, black jack lands, chinquapin lands, grass 
 lands, wheat lands and truck lands. These names convey a very good 
 impression of the character and texture of the soil, and they should 
 be more generally used. When a soil formation is spoken of as 
 black jack land, the name conveys a distinct impression of the kind of 
 soil, for a soil must have a certain characteristic texture to produce 
 such a growth. 
 
 We have not been able to include this botanical work on the 
 different soil formations of the State this year, but it will be made a 
 subject of careful investigation. In the mean time and until a de- 
 scription better suited to the agricultural interests can be giv^en, the 
 geological names will have to be used to designate these different soil 
 formations. 
 
 y. Soil Types. 
 
 The soils of the State appear, at first sight, to offer an endless 
 field of research in the great variety often seen on a single farm and 
 in the same field, but a more comprehensive view of the matter will 
 show this to be due to local causes, which have mixed up and modi- 
 fied the original soil formation. These local modifications may be 
 neglected for the present, until the general features of the repre- 
 sentative soils of the region have bteen worked out. 
 
 The characteristic properties of great soil formations, or soil types, 
 must first be determined, and then more detailed work may be done 
 in the examination of soils of local interest. Why will not truck, 
 tobacco, wheat and grass grow equally well on all soils? It is not so 
 much a matter of plant food as of the texture of the soil. 'No addi- 
 tion of mere plant food in the form of fertilizers or manure will 
 change at once a light sandy soil into a good wheat land. It takes no 
 very great experience to tell at a glance the condition of a soil, and 
 to what class of plants it is best adapted. It is from the ajpjpearance 
 of the soil, that is, from the texture and structure, that this judgment 
 is formed. 
 
EXPERIMENT STATION. 265 
 
 This is the key to soil investigations. It is not until this problem 
 has been mastered and these very evident differences in soils have 
 been explained, that the real and full value and application of the 
 chemical determinations in plants and soils will be seen. As a rule, 
 the chemical analysis of a soil will not enable a farmer to determine 
 to what his land is best adapted ; but, on the contrary, the farmer, 
 from his experience and judgment, must inform the chemist on this 
 point, and must tell him of the strength and condition of the land. 
 
 What are the characteristic properties of a good wheat land, of the 
 best tobacco soil, of the best grass land, of the best land for market 
 truck ? What is it in the appearance of a soil which enables a farmer 
 to place it in one or the other of these classes ? The truck lands of 
 Southern Maryland are "lighter" in texture than the best tobacco 
 lands, and still "lighter" than the best wheat lands. The wheat 
 lands of Southern Maryland are " lighter " than the grass and wheat 
 lands of I^^orthern and Western Maryland. 
 
 It is only after the characteristic properties of a number of soils 
 of well marked agricultural value have been carefully determined 
 that we may hope, by examination and comparison, to suggest meth- 
 ods for the improvement of other soils of local interest. We must 
 have, first of all, a basis of comparison in well known and represen- 
 tative soils. 
 
 We have made several extended trips into Southern and Western 
 Maryland, collecting a large number of samples of soils and sub-soils 
 of representative agricultural value and importance. These samples 
 have been arranged in groups, according to their agricultural value 
 and their geological origin ; and equal weights of the samples in each 
 group have been mixed together, forming a composite sample repre- 
 senting the type of the soil formation. We have, in this way, classi- 
 fied the soils of all the principal agricultural regions of the State, and 
 they are represented by comparatively very few type samples, as 
 shown in the following table : 
 
 The formations are not given in the order of their geological origii^ 
 but according to their agricultural importance and distribution. 
 
266 
 
 MARYLAND AGKICULTURAL 
 
 
 Table 3 : — Soil Types in Maryland. 
 
 Sample. 
 
 Soils adapted to, 
 
 Localities. 
 
 Geological formation. 
 
 276. 
 
 Pine barrens. 
 
 *(2) 
 
 Lafayette, 
 
 283-4. 
 
 Market truck. 
 
 (6-8) 
 
 Eocene. 
 
 285-6. 
 
 Tobacco. 
 
 (9-9) 
 
 Neocene. 
 
 279-80. 
 
 Wheat. 
 
 (7-14) 
 
 Neocene. 
 
 277-8. 
 
 Wheat soil of river 
 terraces. 
 
 (5-5) 
 
 Columbian terrace. 
 
 
 Barren clay hills. 
 
 
 Potomac. 
 
 
 Grass and wheat. 
 
 
 Trenton chazy limestone. 
 
 287-8. 
 
 Grass and wheat. 
 
 (2-4) 
 
 Helderberg limestone. 
 
 238. 
 
 Grass and wheat. 
 
 (1) 
 
 Catskill. 
 
 281-2. 
 
 Grass and wheat. 
 
 (4-5) 
 
 Triassic red sandstone. 
 
 290. 
 
 Mountain pasture. 
 
 (3) 
 
 Oriskany, 
 
 289. 
 
 Poor mountain pasture. 
 
 (6) 
 
 Chemung, Hamilton, Ni- 
 agara, Clinton. 
 
 The Lafayette, Eocene, Neocene and Columbian terrace formations 
 occur in Southern Maryland; the Potomac formation is a narrow 
 belt extending across the State on the line of the B. and O, and the 
 B. and P. railroads; the Trenton chazy limestone forms the Frederick 
 and Hagerstown Valleys; the Triassic red sandstone covers a con- 
 siderable area to the north and south of the Frederick Valley; the 
 Helderberg limestone, Catskill, Oriskany, Chemung, Hamilton, Ni- 
 agara and Clinton formations form the valleys, hills and mountains 
 of Western Maryland. 
 
 In the Piedmont Plateau of Northern Central Maryland, there are 
 grass and wheat soils from gneiss, granite, gabbro and limestone; 
 wheat and tobacco soils from mica schist; corn lands from sandstone; 
 and barren hills from serpentine. 
 
 There has been no opportunity this year to collect samples of soils 
 from the Eastern Shore, 
 
 There are two or three mountain formations wliich occur in such 
 small areas that their soils have not been considered here. The coal 
 formation is so uneven, with its succession of sandstones, limestones 
 
EXPERIMENT STATION. 267 
 
 and shales, whicli have not been separated on the geological map, 
 that, although it is of importance from covering a large area, it has 
 not, as yet, been considered. 
 
 The coarse sands of the quarternarj formation, covering the ex- 
 treme lower part of the State, have not been sampled. 
 
 In the table, where a double number is given, the first number re- 
 fers to the sample of soil, and the second number to the subsoil. 
 Where a single number is given for a type, there is no perceptible 
 difEerence between the soil and subsoil in the localities visited. 
 
 The iigures in brackets under * give the number of localities from 
 which samples were taken to make up the samples of type soils and 
 subsoils. 
 
 The grass and wheat soils of the different types in the Piedmont 
 Plateau and Western Maryland differ in texture and in relative fer- 
 tility, and should be distinguished by different botanical characters, 
 but for the present the geological names will be used to designate 
 them. 
 
 The truck, limestone and Catskill lands are important soils, which 
 should have moi'e localities represented in the type samples. 
 
 To establish a type, samples should be taken from as many locali- 
 ties as possible; from ten localities at least, even in as small a State 
 as Maryland. The type sample is, therefore, a sort of composite 
 sample made by mixing equal weights of samples from a number of 
 localities in each formation. 
 
 A description of the samples tliemselves will be given later. They 
 were taken with a spade, or auger, the soil being taken down to the 
 change of color, and the subsoil below this to a depth depending 
 upon the nature and depth of the material, usually 12 to 18 inches. 
 
 The soil of the pine barrens is a coarse yellow sand, very loose 
 and incoherent when worked, but packed exceedingly hard and tig'ht 
 ■ in the subsoil. The lands are very infertile. These soils should be 
 more carefully examined, and more samples of them should be taken 
 for our type sample, as they cover such an extensive area in Soutliern 
 Maryland with pine barrens, which will some day, when agricultural 
 lands rise in value, have to be taken up and improved. 
 
 Most of the truck supplied to the Baltimore and the larger North- 
 ern markets, from this State, is produced on a rather narrow belt 
 bordering the Bay and rivers from Baltimore south to West Eiver. 
 This area is largely in the eocene formation, although far down on 
 
268 MARYLAND AGKICULTUEAL 
 
 the river necks the lands are coarser and belong to a more recent 
 formation. 
 
 The truck lands proper are a fine textured, grey or reddish grey, 
 sand. They are naturally fertile, but require care to keep up their 
 fertility. The texture of l^ie soil admits of vast quantities of manure 
 and organic refuse being used for forcing the vegetables, without fear 
 of clogging the soil. The texture of these lands adapt them well to 
 the requirements of market gardening. 
 
 The soils are derived from the weathered green sands, similar in 
 composition to the green sand marls of Kew Jersey, so that in chemi- 
 cal composition they should be rich in potash and phosphoric acid. 
 
 The soils are too light in texture for wheat, although, in the high 
 state of cultivation to which they are brought for market truck, good 
 crops of wheat may be produced, but at such a cost, and under such 
 artificial conditions, that the soil cannot, in any sense, be called a 
 wheat soil. 
 
 Samples have been taken from too few localities in the truck area 
 to make the type samples of soil and subsoil (Nos. 283-4) perfectly 
 satisfactor3^ They are probably heavier than the best type of truck 
 land. The collection of these samples has been rather incidental to 
 other work, as most of our attention has been given this year to the 
 tobacco and wheat soils of Southern Maryland. The great truck 
 area between Baltimore and Annapolis is not represented in these 
 samples. 
 
 The best tobacco and wheat lands in Southern Maryland, apart from 
 the river terraces, seem to be confined to the diatomaceous earth 
 horizon of the neocene formation, or of a later formation made over 
 out of this same material. The formation extends obliquely across 
 the peninsula, in rather a broad belt from South River and Herrino- 
 Bay to Pope's Creek on the Potomac River. 
 
 The subsoil of the wheat land is a strong clay -loam of a very 
 marked and characteristic texture and yellow color. It is usually not 
 more than 4 to 6 feet deep, resting directly on the white diatomaceous 
 earth, and appears to be formed from this by weathering, as there is 
 no distinct line of separation. The samples of both wheat and tobacco 
 subsoils still contain many diatoms. The weathering of this diato- 
 maceous earth probably takes place quite rapidly on exposure, and 
 some interesting changes occur, including a local accumulation 
 
EXPERIMENT STATION, 269 
 
 of clay in the yellow subsoil, which should be further studied. We 
 have the material for this work, but it has not been worked out yet. 
 
 Wheat and tobacco are commonly grown on the same land in alter- 
 nate years or in longer rotation, but the strongest and best wheat land 
 is too heavy for tobacco. It gives a large yield but makes a coarse, 
 thick tobacco leaf which is sappy and cures green and does not take 
 on color. The best class of tobacco lands, where the finest grade of 
 tobacco is produced, is of lighter texture and too light for the best 
 wheat production. The best tobacco soils around Upper Marlboro 
 appear to be at a lower elevation than the strongest wheat lands, and 
 are rather heavier in texture than the better grade of tobacco lands in 
 the ]^ottingham, Aquasco and Chaneyville regions. These latter are 
 more loamy, although they are still over very pure deposits of diat- 
 om aceous earth. 
 
 At a road cut near Upj3er Marlboro there is an exposure of diato- 
 maceous earth, probably 30 or 50 feet deep. The upper part of this 
 exposure is very pure white earth, very light and porous, A strong 
 wheat subsoil rests directly on this. The lower part of the exposure 
 is decidedly more sandy in texture, and more like the typical tobacco 
 land. The lighter texture of the tobacco soils may be due to local 
 modifications of original wheat lands, or they may themselves turn 
 into good wheat soils by further weathering, or these tobacco lands 
 may belong to a different horizon of the diatomaceous earth form- 
 ation. The last seems very probable, but it may be due to different 
 causes in different localities. 
 
 Lime is the great fertilizer for all classes of soils in this region. 
 On the lighter soils lime must be used only with organic matter, or it 
 will "burn out the land." Lime every five years, and clover, will 
 keep up their wheat lands. But this rule is being neglected. Lime 
 is applied more i-arely and the lands are becoming clover-sick. The 
 wheat and tobacco lands are deteriorating. This cannot be due solely 
 to a loss of plant food from the soil, for there is undoubtedly a change 
 of texture of the soil, very apparent to the eye, which must change 
 the relation of the soil to the circulation of water and to crop pro- 
 duction. What these changes are which take place in the soil, must 
 be fully investigated and must be well understood before the most 
 intelligent methods can be proposed for the recovery and improve- 
 ment of the lands. 
 
 The fertile terraces bordering the rivers of Southern Maryland are 
 very level and very uniform in appearance. They extend about half 
 
270 MARYLAND AGRICULTUKAL 
 
 a mile inland from the rivers. The soil is a fine grained loam and 
 the subsoil a jellow clay loam. It would be classed as a good strong 
 wheat soil, very easily worked and naturally very fertile and capable 
 of the highest state of cultivation. They ai-e similar in appearance 
 to the "ridge lands" of the south. Recently the fertile valley lands 
 along the B. & O. R. E,., between Baltimore and Washington, (here- 
 tofore considered part of the Potomac formation,) as well as other 
 lands in the vicinity of Baltimore, have been classed with the Colum- 
 bian terrace formation, but these localities are not represented in our 
 type samples. 
 
 The barren clay hills crossing the State in a broad belt from Wash- 
 ington, along the two railroads, to the Delaware line, belonging to the 
 Potomac formation, have not been sampled. 
 
 The fertile soils of the Frederick and Plagerstown Yalleys, formed 
 by the disintegration of the Trenton limestone, are very heavy, red 
 clay, well suited to grass and wheat. They are much stronger than 
 the wheat lands of Southern Maryland. It takes a strong, heavy soil 
 for grass and these are naturally good grass lands. We have a 
 number of samples from different localities but not enough to make a 
 satisfactory type sample. 
 
 The Triassic red sandstone covers a considerable area to the north 
 and south of the limestone formation in the Frederick valley, with a 
 dark, Indian red, heavy clay soil. It is very productive but is not so 
 safe or certain as the limestone soil. Like the limestone soil, it is 
 greatly benefited by an application of lime. 
 
 The Helderberg limestone (cement rock) forms a small area of 
 fertile hill and valley lands west of Hagerstown. The subsoil is a 
 strong yellow clay, naturally well drained, and capable of a high 
 state of cultivation. The land is well adapted to grass and wheat. 
 
 The soil appears very uniform in texture and the type sample is 
 considered fairly satisfactory. 
 
 The Catskill formation gives a very strong soil, well suited to both 
 grass and wheat. It has a very characteristic dark red color. 
 
 The other formations are found in narrow belts forming the hills 
 and mountain ranges, and, so far as I have seen, they are generally 
 very poor and stony. There is often no perceptible difference 
 between the soil and subsoil of these mountain formations, and where 
 they cannot be distinguished, a sample is taken down to 12-18 inches 
 and classed with the subsoils. 
 
EXPERIMENT STATION. 271 
 
 A description of the soils and subsoils whioh Jiave been used to 
 mahe ttp the type samples. 
 
 Pine Barrens. 
 
 "276. Type sample from the following localities : 
 
 209. Coarse jellow sand and gravel overlying neocene at Cove Point, 
 
 three miles north of Drum Point. 
 
 210. Coarse jellow sand from bluff at Jones' wharf, Patnxent River. 
 
 Truck Land. 
 '283. Type sample of soil frorru the folloioing localities : 
 
 144. Sandy soil from Patuxent, near Governor's Bridge. Naturally 
 
 rather poor and unproductive but would make good truck and 
 is typical watermelon land. 
 167. Sandy soil from a peach orchard at Mitchell ville. 
 
 170. Soil of light lands west of Hall's Station. From the farm of 
 
 J. Berry. Yery characteristic truck land and of considerable 
 area here. 
 
 267. Soil of truck land from farm of J. Birch, South River Neck. 
 
 269. Sandy soil of truck land. South River Neck. 
 
 271. Soil of truck land east of Hill's Bridge. 
 
 284. Type sample of subsoil from the following localities: 
 
 145. Sandy subsoil from near Governor's Bridge. Under 144. 
 
 158. Subsoil of pine land on the "Ridge road" near Cheltenham, 
 A compact red sand which should make good truck land. 
 There is a large area of this land here, probably of Lafayette 
 or possibly of neocene origin. 
 
 166. Subsoil from B. D. Mullikin's farm, between Hall's Station and 
 Mitchellville. Characteristic truck land of that region, show- 
 ing green grains of glauconite and of undoubted eocene origin. 
 
 169. Subsoil from peach orchard at Mitchellville, from nnder 167. 
 
 171. Subsoil of light lands west of Hall's Station, under 170. 
 
 268. Subsoil truck land, from under 267, from the farm of J. Bir cli 
 
 South River Neck. 
 
 270. Subsoil of truck land, from under 269, South River Neck. 
 
 272. Subsoil truck laud, from under 271, east of Hill's Bridge. 
 
 These soils and subsoils are undoubtedly of eocene origin 
 except 158, and possibly 269 and 270, which were far down on 
 the Neck and may be of more recent origin. 
 
272 makyland agricul'iueai, 
 
 Tobacco Land. 
 ^85. Type sample of ^o\\,froin the following localities: 
 
 146. Soil from Clias. W. Sellman's farm near Davidsonville. 
 
 Rather light for wheat but makes good tobacco and corn. 
 
 161. Loam soil from J. H. Sasscer's farm near Upper Marlboro. A 
 deep loam, lying rather low and much lighter than the best 
 wheat lands. It is a fair type of the tobacco lands of Marl- 
 boro district, but is rather heavy for tobacco, making rather a 
 heavy, coarse leaf. It is heavier than the I^Tottingham or 
 Chaneyville tobacco lands Wheat, on this land, is inclined to 
 go to straw and not produce much grain. 
 
 163. Soil of H. H. Sasscer's tobacco land, North Keys. Considered 
 rather heavier than the best type of Nottingham tobacco land. 
 It makes a very fine grade of tobacco. 
 
 255. Loam soil from W. H. Hopkins, Bristol. Light in texture and 
 a very iine quality of tobacco land. Considered very fertile 
 but rather light for wheat. 
 
 257. Soil of tobacco land from Fred. Sasscer's farm, Upper Marlboro. 
 
 259. Soil of tobacco land from the river terrace at Nottingham. The 
 soil is coarser than most of the river terraces examined. This 
 grade of soil appears to be of rather small area. The terraces 
 extend about half a mile inland from the river and produce a 
 fine quality of tobacco. 
 
 261. Soil from a farm near Chaneyville. It is considered the very 
 finest grade of tobacco land. 
 
 263. Soil of a fine grade of tobacco land near Nottingham. 
 
 265. Soil of a very fine type of tobacco land from the farm of J. F. 
 Talbott, Chaneyville. 
 
 286. Type sample of svhsoil from thefollotoing localities: 
 
 Samples 118, 162, 164, 256, 258, 260, 262, 264, 266, from 
 under the soils just given, and in the corresponding order. 
 These soils and subsoils are of neocene origin or formed of neocene 
 
 material, except 259, 260, 263, 264. Diatoms were found in most of 
 
 the subsoils. The finest tobacco lands are lighter in texture than the 
 
 best wheat lands. 
 
EXPERIMENT STATION. 
 
 273 
 
 Wheat Land. 
 '279. Type sample of 9,011. from, the folloioing localities : 
 
 140. Loam soil from near Davidson ville, fairly representing the 
 
 wheat lands of this locality. It appears somewhat light 
 for wheat, and is not considered as productive as it was 
 years ago. It does not produce the clover crops it once 
 did, which were such an excellent preparation for wheat. 
 The lands have deteriorated. The finest wheat lands now are 
 the hill lands where this loam has not accumulated, or has been 
 removed by subsequent washing, leaving exposed a yellow clay 
 loam like 142. 
 
 154. Clay soil from J. H. Sasscer's farm near Upper Marlboro. 
 Yery line wheat land, similar to the Davidsonville and West 
 River lands. Too heavy for tobacco, the plant being sappy and 
 curing green. These lands are of considerable area around Marl- 
 boro, extending up nearly to Mitchellville on the east of the 
 railroad, and forming the bottom lands and hills, west of the 
 Western Branch of the Patuxent, but becoming much lighter 
 in texture south of Marlboro. 
 
 178. Clay soil at the base of the neocene, at Herring Bay. Good 
 strong wheat land, very similar to the preceding localities. 
 
 183. Soil of wheat land from James Chapman, Pope's Creek. This 
 land carries a good grass sod. 
 
 249. Soil of wheat land from J. F. Talbott, Chaneyville. 
 
 251. Soil of the fertile wheat lands of West River. 
 
 253. Loam soil from Mt. Zion. Yery characteristic wheat land, simi- 
 lar to those of Davidsonville and West River. 
 
 2W. Type sample of subsoil from the folloioing localities : 
 
 141. Loam subsoil from under 140, from near Davidsonville. It has 
 
 good body but not the consistancy of the next sample. It 
 , fairly represents the lands around here where washing has not 
 occurred. The loam is fi'om two to four feet deep. 
 
 142. Yellow clay subsoil fi'om under the above, taken in a road cut- 
 
 This forms the very best wheat land when exposed. It has 
 the very characteristic color and texture of the best wheat 
 lands in Southern Maryland. 
 
274 MARYLAND AGRICULTURAL 
 
 155. Clay subsoil of wheat land from under 154, from the farm of 
 
 J. H. Sasscer, near Upper Marlboi"0. 
 
 156. Yellow clay subsoil under the "gravelly lands" of Hosaryville. 
 
 This is undoubtedly neocene or neocene material. A fair 
 quality of diatomaceous earth was found in a road cut near by, 
 directly underlying this and gradually passing from the white 
 earth into the yellow clay above. The country is covered 
 generally with a thin layer of fine gravel, which is hardly 
 noticed in cultivated fields and is often absent. The gravel 
 extends down into the undisturbed clay and is probably part of 
 the same formation, although there may be a light coating of 
 Lafayette here, made out of the neocene material. The lands 
 make a very fine quality of tobacco but are generally too light 
 for wheat. When this clay is exposed without the gravel, 
 however, it makes a very fine wheat land. On Mr. Holloway's 
 place, between Rosaryville and Woodyard, and near where this 
 sample was taken, they made a very fair qualitj^ of brick some 
 years ago from the subsoil of the wheat field. 
 
 179. Clay subsoil of tlie wheat lands of Herring Bay, from under 178. 
 
 180. Yellow clay subsoil from over diatomaceous earth, from a bluff 
 
 three .miles north of Plum point. 
 
 181. Yellow clay subsoil of wheat land, from under 183, from the 
 
 farm of James Chapman, Pope's Creek. 
 245. Subsoil f wheat land opposite the church at Davidsonville. 
 It is in a fine state of cultivation. 
 
 216. Subsoil of wheat land about one half mile west of Davidson- 
 
 ville. 
 
 217. Subsoil of wheat land, now in grass, from the farm of James 
 
 Iglehart, Davidsonville. 
 
 218. Subsoil of wheat land from the farm of P. TI. Israel, David- 
 
 sonville. 
 250. Subsoil of wheat land from the farm of J. F. Talbott, Chaney- 
 
 ville. From under 249. 
 252. Subsoil of wheat land, from under 251, South River. 
 254. Subsoil of wheat land, from under 253, Mt. Zion. 
 
 PivER Terrace. 
 ^77. Type sample of soil from the following localities: 
 198. Loam soil from a wheat field opposite P>enedict. 
 
EXPERIMENT STATION. 
 
 2T5 
 
 200. Loam soil from a corn field below St. Mary's. This soil is 
 naturally fertile and is capable of great improvement. An 
 excellent wheat soil. 
 
 202. Loam soil from Mr. Broome's wheat land, St. Mary's. 
 
 204, Loam soil from a wheat field opposite St. Mary's. > 
 
 206. Loam soil from Clifton Beach. Good wheat land. 
 
 278. Tijpe sain])le of subsoil from the following localities: 
 Samples 199, 201, 203, 205, 207, are subsoils from under the 
 above soils, given in the same order. 
 
 Heldeebeeg Limestone. 
 
 287. Tyi?e sam])le of soil from the following localities: 
 
 221. Soil from near Hancock. Very fertile grass and wheat land. 
 
 222. Soil from near Hancock. 
 
 288. Type sample of subsoil from the following localities: 
 220. Yery fertile grass and wheat land two miles west of Hancock, 
 
 No change in 18 inches. 
 
 223. Subsoil near Hancock. 
 
 224. Characteristic yellow subsoil of the Helderberg limestone, 
 
 from a wheat field two miles west of Hancock. Contains 
 many small fragments of undecomposed rock. 
 
 225. Subsoil from near Cumberland. Naturally rather poor but has 
 
 good body and is very fertile where improved. 
 
 Catskill. 
 
 238. Type sample of the Catskill formation, from near Mt. Savage. 
 Good strong land for grass and wheat. Has a characteristiCy 
 dark red color, 
 
 Oriskany. 
 290. Type sample of Orishany from the follo%oing localities: 
 226 and 227, from near Cumberland, and 228, from Hancock. The 
 formation is not very uniform in texture. The localities 
 visited have rather a fine textured soil, naturally poor but 
 capable of some improvement. The formation occurs only in 
 narrow belts capping hills and mountains, and is not of much 
 extent in the State. 
 
276 maryland agricultural 
 
 Chemung, Hamilton, Niagara and Clinton. 
 ^89. Type sample from the following localities : 
 
 234. Subsoil of the Hamilton shale, from near Mt. Savage. I^atur- 
 
 allj very poor but capable of some improvement as it has good 
 body. 
 
 235. Hamilton shale, from Cumberland. Poor lands — mostly thin 
 
 mountain pastures. 
 236 and 237, Chemung from two localities near Mt. Savage. Nat- 
 urally rather poor land. 
 
 239. Niagara from near Cumberland. Poor but has good body and 
 
 is capable of some improvement. 
 
 240. Clinton shale from near Cumberland. Lands naturally poor but 
 
 have good body. 
 
 These formations appear so much alike in texture and agricultural 
 features that they are all included in the one type. They are nearly 
 all hill and mountain pastures, naturally poor and not capable of 
 great improvement, except as garden spots and at great expense. 
 The soil or rather subsoil, for there is little or no difference, is a very 
 fine grained, powdery material, filled with small fragments of the 
 original rock. 
 
 YI. Mechanical Analysis of the Type Soils. 
 
 The soils of these type formations differ so much in texture that 
 the difference is quite apparent to the eye. Some are coarser than 
 others, the grains are larger and there are fewer of them in a given 
 weight of soil. The first thing done, in the examination of the 
 soil, was to make a mechanical analysis by separating the grains 
 into groups, according to size. The approximate number of grains 
 in each group was then calculated and this shows how much 
 the empty space in the soil has been divided up and, relatively, how 
 fast water will move through the different soils. 
 
 For the greatest accuracy, the grains should be separated into a 
 large number of groups, so that all the grains in each group shall 
 be very nearly of the same size, but the analysis takes so long that 
 we have used only eight groups. The separations were made sub- 
 stantially after Johnson and Osborn's "beaker method." We have 
 taken ,0001 mm. as the lowest limit of size of the grains of clay, 
 based on many measurements we have made. The clay group has 
 
EXPERIMENT STATION. 277 
 
 relatively wide limits (.005-.0001 mm.) but we have not attempted a 
 further separation than this. A millimeter (1 mm.) is equivalent to 
 about 1-25 th of an inch, so that the smallest grains of clay are about 
 1-25400 inch or .0000039 inch in diameter. 
 
 Table 4, gives the results of the mechanical analysis of the type 
 samples of the subsoils of the five formations in Southern Maryland. 
 The analyses and calculations based on the other type samples will 
 not be completed in time for this report."^ The subsoils have been 
 taken up first, as the texture of the subsoil is more important in 
 determining the nature of the land and its relation to the water 
 supply of crops than that of the soil itself. 
 
 Table 4: — Mechanical Analyses of Type Subsoils. 
 
 
 
 276. 
 
 284. 
 
 286. 
 
 280. 
 
 278. 
 
 Diameter. 
 mm. 
 
 Conventional 
 names. 
 
 Pine 
 barrens. 
 
 Truck. 
 
 Tobacco. 
 
 Wheat. 
 
 River 
 terrace 
 
 2-1 
 
 Gravel 
 
 tl.87 
 
 0.6« 
 
 1.36 
 
 0.00 
 
 1.60 
 
 1-.5 
 
 Coarse sand 
 
 9.15 
 
 2.89 
 
 2.13 
 
 0.42 
 
 1.51 
 
 .5-. 25 
 
 Medium sand 
 
 38.37 
 
 21.85 
 
 7.78 
 
 1.81 
 
 4.15 
 
 . 25- . 1 
 
 Fine sand 
 
 33.28 
 
 25.82 
 
 16.57 
 
 8.59 
 
 4.84 
 
 .1-.05 
 
 Very fine sand 
 
 3.52 
 
 18.38 
 
 19.83 
 
 32.06 
 
 8.54 
 
 .05-. 01 
 
 Silt. 
 
 3.47 
 
 9.48 
 
 25.41 
 
 23.65 
 
 44.92 
 
 .01-. 005 
 
 Fine silt 
 
 1.55 
 
 3.37 
 
 4.52 
 
 6.77 
 
 5.78 
 
 .005-. 0001 
 
 Clay 
 
 3.75 
 
 15.30 
 
 17.95 
 
 22.55 
 
 25.85 
 
 
 
 97.96 
 
 97.77 
 
 95.55 
 
 95.85 
 
 97.19 
 
 Organic matter, water, loss. . 
 
 2.01 
 
 2.23 
 
 4.45 
 
 4.15 
 
 2.81 
 
 tThis includes 1.81 per cent, larger than 2mm. in diameter. 
 Note. — Each of these type samples is made up of samples from a number of 
 localities in each soil formation. 
 
 The results in this table are confusing from the mass of figures, 
 and from the fact that each group has to be given a special value, 
 depending upon the size of the soil grains which it contains ; a per 
 cent, of clay having far more value than an equal amount of 
 gravel. From this table alone it would be difficult to judge of the 
 texture of the soils. 
 
 YII. Approximate Number of Grains per Gram of Soil. 
 From the results in Table 4 we have calculated the approximate 
 number of grains of sand and clay in one gram of the subsoils, as 
 ■■■■This matter has since been completed and will be given in an appendix. 
 
278 
 
 MARYLAND AGKICULTUEAL 
 
 given in Table 5. These figures are, of course, onl)' approximate and 
 the numbers are far beyond our comj)rehension. Thej may be used 
 relatively, however, in comparing one soil with another. 
 
 ■ ?* 
 o 
 
 w 
 
 o 
 
 M 
 
 <! 
 
 H 
 
 (4 
 
 
 
 
 o 
 
 
 CO 
 
 o 
 
 p 
 
 CO 
 
 p 
 
 N 
 
 C/J 
 
 
 f^ 
 
 
 O 
 
 
 g 
 
 
 ^ 
 
 
 M 
 
 
 d' 
 
 U> 
 
 « 
 
 00 
 
 a 
 
 
 
 
 T) 
 
 
 ^3 
 
 
 C 
 
 
 ^ 
 
 
 cS 
 
 ■ c 
 
 cS 
 
 
 
 cc 
 
 V 
 
 OJ 
 
 
 a 
 
 
 C 
 
 ;i5 o 
 
 o a 
 
EXPERIMENT STATION. 279 
 
 It will be remembered that the texture of the soil is determined by 
 the size and, therefore, by the number of grains per unit weight or 
 volume of soil. In this table it will be seen that the number of 
 grains in the fine "silt" and "clay" groups so far exceed the number 
 in all the other groups combined, that they, and especially the clay, 
 actually determine the extent of subdivision of the empty space in 
 the soil. The other groups may be neglected, for practically, the 
 effect of the gravel and sand, is only to diminish the amount of clay 
 per unit weight or volume of soil. The amount of clay is, therefore, 
 a very important factor in any soil as it practically determines the 
 subdivision of the empty space and the texture of the land. 
 
 Table 6 : — Total I^umber of Grains in One Gram. 
 
 {Summary of Results in Table 5.) 
 
 276 Pine barrens *(2) 1692 000 000 
 
 284 Truck ,. . . (8) 6 868 000 000 
 
 286 Tobacco (9) 8 258 000 000 
 
 280 Wheat (14) 10 358 000 000 
 
 278 River terrace (5) 11 684 000 000 
 
 Limestone (grass land). . . (1) 24 653 000 000 
 
 * Number of localities represented. 
 
 The summary of the results in Table 6 places the soils at once in 
 their true agricultural relation. It suggests also a method for the 
 classification of soils. 
 
 From the mechanical analysis of the samples which were used to 
 make np these type samples, and perhaps of a large number of 
 other soils of known agricultural value, it should be possible to 
 determine the smallest and the largest number of grains per gram 
 of soil where these different crops could be successfully grown. For 
 example, no crop can. be successfully grown, except under highly 
 artificial conditions of manuring with organic matter, or by irriga- 
 tion, on a soil having so few as 07ie thousand seven hundred million 
 grains per gram. Good m.arket truck is grown on a soil having six 
 thousand eight hundred million grains. Now what is the limit 
 between these two figures where the soil becomes too light for market 
 truck? Good wheat is grown on a soil having ten thousand millioii 
 grains per gram, and this must be near the limit of profitable wheat 
 
280 MARYLAND AGRICULTURAL 
 
 production, for eight thousand 'million grains per gram gives a soil 
 rather too light for wheat, but well suited to tobacco. A soil having 
 ten thousand million grains per gram is too light for grass, which 
 thrives on a limestone soil having twenty-four thousand million. 
 Our type soils should, therefore, sliow the range for the profitable 
 production of a given crop. We should be able also from the 
 mechanical analysis of an unknown soil to give it its true agricultural 
 place by reference to these established soil types. 
 
 It is not to be inferred from these statements that wheat cannot be 
 grown on a soil having so few as one thousand million grains per 
 gram. This number represents merely the skeleton, or frame- 
 work, of the soil. As we shall see later, this may be so filled in 
 and modified by organic matter as to enable it to support a good 
 wheat crop, but at such an expense as to put it far outside the limit 
 of profitable culture. This is a matter of judgment and experience. 
 The soil types give only the skeleton structure of the soil. 
 
 Nor is it to be inferred that wheat may be grown on all soils having 
 ten thousand m^illion grains or more per gram with equal success, for 
 the relation of these soils to water, upon which the cropping depends, 
 is a matter not only of how much the space within the soil is subdivided, 
 that is, how many grains there are, but depends also upon the way 
 these grains are arranged. We will develop this idea further, when 
 we come to speak of the cause of the deterioration of lands and of 
 their improvement. 
 
 YII. Approximate Extent or Surface Area per Cubic Foot of Soil. 
 
 We are able, from the foregoing i^esults, based on the mechanical 
 anlysis of the soils, to calculate the approximate extent of surface 
 area of the grains of clay and sand in a given weight or volume of 
 soil. 
 
 A solid block of granite, one foot square and one foot high, would 
 have six square feet of surface area, but when this cube of solid rock 
 disintegrates, forming or leaving a cubic foot of soil, half of the rock 
 is dissolved and carried off and wliat remains is split up into a vast 
 number of separate grains of sand and clay. If a soil were made U2> 
 of fragments as large as this cubic foot of rock, then, even if the 
 proper water supply could be maintained in the soil, it would be 
 impossible for our staple crops to get their needed food supply. 
 The soil moisture and the roots themselves can only dissolve food 
 
EXPERIMENT STATION. 
 
 281. 
 
 material from the surface of the rock. The rock is exceedinglj 
 insoluble and the amount of plant food which could be dissolved and 
 extracted from six square feet of surface by water or roots, would be 
 exceedingly small and entirely insufficient for the needs of any of our 
 staple crops. 
 
 The soil, however, resulting from the disintegration of such a rock 
 has an enormous extent of surface area if all the surface on the 
 separate grains of sand and clay be considered. Table 7 gives the 
 approximate extent, in square centimeters, of the surface area in one 
 gram of our type subsoils and of a limestone subsoil from Frederick 
 Yalley. Table 8 shows the approximate number of square feet of 
 surface area in one ciibic foot of soil. 
 
 Table 7: — Surface Area {sq. cm.) per Gram of Subsoil. 
 
 276. 284. 286. 280. 279 
 
 Diameter. Conventional 
 
 mm. 
 2-1 
 1-.5. 
 .5-.25 
 .25-.1 
 
 .1-.05 
 .05-.01 
 
 names. 
 Gravel 
 Coarse sand 
 Medium sand 
 Fine sand 
 Very fine sand 
 Silt 
 
 .01-.005 Fine silt 
 .005-.0001 Clay 
 
 Pine 
 barrens. 
 
 0.5 
 
 2.8 
 23.6 
 43.9 
 10.8 
 26.7 
 47.7 
 339.8 
 
 Truck. Tobacco. Wheat. 
 
 0.1 
 
 1.0 
 
 13.5 
 
 34.1 
 
 56.7 
 
 73.1 
 
 104.1 
 
 1387.0 
 
 0.2 
 
 0.7 
 
 4.9 
 
 22.4 
 
 62.5 
 
 200.7 
 
 142.8 
 
 0.0 
 0.1 
 
 1.1 
 
 11.6 
 100.9 
 186.2 
 213.2 
 
 River 
 terrace 
 
 0.2 
 
 0.5 
 
 2.6 
 
 6.4 
 
 26.5 
 
 348.7 
 
 179.5 
 
 1668.0 2089 2360.0 
 
 Limestone, 
 
 0.0 
 
 0.0 
 
 0.1 
 
 0.4 
 
 7.6 
 
 221.3 
 
 344. a 
 
 5000.0 
 
 495.8 1669.6 2102.2 2602.1 2924.4 5573.7 
 
 Table 8 : — Square Feet of Sprface per Cubic Foot of Subsoil. 
 
 276 .... 
 
 Pine barrens. . . . 
 
 23 940 
 
 square feet. 
 
 284 
 
 Truck 
 
 74 130 
 
 11 II 
 
 286 
 
 Tobacco. 
 
 84 850 
 
 11 
 
 280 .... 
 
 Wheat 
 
 94 540 
 
 .. 
 
 278 
 
 Eiver terrace .... 
 
 106 200 
 
 11 u 
 
 
 
 (2.3 acres.) 
 
 
 Limestone 
 
 202 600' 
 (158 OOC 
 
 square feet. 
 ) aeres.) 
 
 
S82 MARYLAND AGRICULTURAL 
 
 It will be seen that there are upwards of 24,000 square feet of sur- 
 face area in a cubic foot of the subsoil of the pine barrens, no less 
 tlian 100,000 square feet, or 2.3 acres, of surface area in a cubic foot 
 of the subsoil of the river terrace, and 158,000 square feet of sur- 
 face area in a cubic foot of the limestone subsoil. 
 
 These figures seem vast, but they are probably below, i-ather than 
 above, the true values on account of the wide range of the diameters 
 of the clay group, as given in the table. This gives an enormous 
 area for the roots and soil moisture to act on for the extraction of 
 plant food from the mineral elements of the soil. Instead of the few 
 square feet offered by the cube of granite, there are now several 
 acres of surface area, for the roots to range over, in search of food 
 and for the water to act on, in a single cubic foot of soil. This great 
 extent of surface and of surface attraction, which has been described 
 as potential in Section II., gives the soil great power to absorb moist- 
 ure from the air, and to absorb and liold back mineral matters from 
 solution. A smooth surface of glass will attract and hold, by this sur- 
 face attraction, an appreciable amount of moisture from the surround- 
 ing air. A cubic foot of soil, having 100,000 square feet of surface, 
 should be able to attract and hold a considerable amount of moisture 
 from the air. 
 
 When a soil is only slightly moistened with water there will be 
 nearly as much exposed water-surface as the surface of the soil grains 
 themselves. The amount of energy or tension on such an extent of 
 water-surface will be very great and it is this which enables a soil to 
 draw up the large amount of water needed by the crop. 
 
 In all of these relations, the extent of surface gives the soil a cer- 
 tain strength and value which must have an important bearing on 
 crop production and distribution. 
 
 IX. The Circulation of Water in these Type Soils. 
 
 We have showm that the number of grains per gram, places these 
 type soils in their true agricultural relation. We have now to show 
 the reason fdr this in the difference in their relation to the circulation 
 of water, and the ease with which a definite quantity of water can be 
 supplied to a given crop. 
 
 We will assume that the grains in all the soils have the same mean 
 arrangement, then the relative rate of circulation, other things being 
 equal, will depend upon how much space there is in the soil and 
 upon how much this space is subdivided. 
 
EXPERIMENT STATION. 283 
 
 For the reasons which have ah'eady been given, we have not been 
 able to determine the amount of space in the soils which were used 
 to make up the type samples. The determinations require much 
 time and great care to remove a definite volume of soil from the field, 
 and this must be made the subject of some future investigation. 
 From our work in South Carolina on similar soils, which has been 
 referred to, we have assumed the per cent, of empty space in each of 
 the soil types, given in the following tables. These values, therefore, 
 are not exact determinations, but are thought to be approximately 
 correct. It is important to observe that the coarser soils have less 
 space and, consequently, when this space is completely filled with 
 water, the sandy soils will contain less water than the clay soils. In 
 a cubic foot of the sandy soils there is considerably less than half a 
 cubic foot of empty space; in the same volume of the clay soils there 
 is over half a cubic foot of space for water to move in. This 
 difference in the amount of space in the different soils, gives rise to 
 an important modification of the relative rate of circulation, when 
 the soils are saturated, and when they are short of saturation. 
 
 The empty space in agricultural soils is hardly ever completely 
 filled with water. The most favorable amount of water in the soil, 
 for growing plants, as Hellriegel and others have shown, is from 30 
 to 50 per cent, of the water-holding capacity of tlie soil. As a light 
 sandy land has less space and will hold less water than a clay soil, the 
 most favorable amount of water for vegetation will be less than in a 
 clay soil. We have repeatedly found in actual determinations, less 
 water in light lands than in heavy clay soils, and it is a matter of 
 observation and experience that light lands are drier than heavy clay 
 soils. 
 
 The reason for this follows from the fact that water circulates 
 more freely in these light soils, by reason of the fewer grains and the 
 less amount of subdivision of the empty space, and after a moderate 
 rain the water passes down more readily into the lower depths of 
 the subsoil. 
 
 After the excess of rainfall has passed down through the soils and, 
 equilibruim is established, there will be less water in the light lands 
 than in the clay soils. If, then, a definite quantity of water is 
 required, by the crop in a given time, it can move up to the plant 
 through the sandy soil more readily, but there is less water-surface 
 in the light land to contract, that is, there is less force to pull the 
 
284 MARYLAND AGRICULTUKAL 
 
 water up. These points are well brought out in the following calcu- 
 lations of the relative rate of circulation of water in these type sub- 
 soils. 
 
 If we assume in the first place, that all the soils contain the same 
 amount of water, namely 12 per cent, (the most favorable amount in 
 the wheat land,) the relative rate of circulation will be as follows : 
 
 iq'o. Soil. .Space. Water-content. Relative time. 
 
 27Q Pine barrens 40 per cent. 12 per cent. 17 
 
 284.. •• Truck 45 " " 12 " " 43 
 
 286 Tobacco 50 " " 12 " " 68 
 
 280... Wheat 55 " " 12 " " 92 
 
 278 River terrace.. . . 55 " •' 12 " " 100 
 
 If it takes 100 minutes for a quantity of water to pass down 
 through a certain depth of the subsoil of the river terrace, the same 
 weight of water could pass down through the subsoil of the truck 
 land in 43 minutes, and through the subsoil of the pine barrens in 17 
 minutes. It could not move up so readily for there is less water sur- 
 face^ as we have shown, to contract and pull it up from below. 
 
 When equilibrium is established and the water is moving down with 
 about the same rate in each of the subsoils, there will be about 6.5 
 per cent, in the subsoil of the pine barrens, 9 per cent, in the truck 
 land and 12 per cent, in the subsoil of the river terrace, as follows: 
 
 ]Sfo. Soil. Space. Water-content. Relative time. 
 
 27g Pine barrens 40 per cent. 6.6 per cent. 102 
 
 284-. •• Truck 45 " " 9.0 " " 102 
 
 285.. •• Tobacco 50 " " 10.5 " " 102 
 
 280 Wheat 55 " " 11.7 " " 101 
 
 278 River terrace. . . 55 " " 12.0 " " 100 
 
 This would be about the relative amount of water found in these 
 subsoils some time after rain. When the subsoil of the river terrace 
 contains 12 per cent, of water, that of the pine barren would contain 
 about 6.5 per cent., that of the truck land, 9 per cent. 
 
 The interesting question suggested above, comes up here again. If 
 the rate of circulation of water through the light truck land with 9 
 per cent, of water present in the subsoil, is the same as in the wheat 
 
EXPERIMENT STATION", , 285 
 
 soil of the river terrace with 12 per cent, of water, (the most favor- 
 able amount for wheat), then why are not the light truck lands as good 
 for wheat as the other ? And the explanation given above is only 
 made clearer through these tables, that while gravity acts with a con- 
 stant force, xoitli surface tension, to pull the water down, surface ten- 
 sion alone has to pull the water up to the crop against gravity ', and 
 there is less surface tension, less contracting power, less force, to pull 
 up a given weight of water in a given time in the light land than in 
 the other. The wheat crop would suffer on such a soil in a warm, dry 
 spell, when it had to depend on water being supplied it from below. 
 
 We have shown that there is less space in the light truck land than 
 in the wheat soils, but the soil grains being larger, there are fewer of 
 them, and the space is not divided up so much. Eacli separate space 
 is larger and, when the soil is short of saturation, the water moves 
 faster. 
 
 If however the soils are fully saturated, the volume of empty space 
 has an important value in retarding the rate of movement. There is 
 less volume of space in the light lands, less water can be crowded 
 into it than in the wheat soils, and so, when the spaces in the soils are 
 fully saturated, the rate of movement will be relatively slower than 
 in the wheat soils. 
 
 The relative rate of movement of water through these different 
 subsoils when all the space is filled with water, will be as follows : 
 
 No. Soil. Space. Water-content. Relative time. 
 
 276-. Pine barrens.. 40 per cent. 20. 10 per cent. (Sat.) 63 
 
 284.. Truck 45 " " 22.41 ' " " 120 
 
 286.. Tobacco ..... 50 " " 27.42 " " " 103 
 
 280 •■ Wheat 55 " " 31.55 " " " 92 
 
 278.. River terrace. 55 " " 31.55 " " " 100 
 
 If all the space is filled with water, as assumed in Table 9, the sub- 
 soils will contain, respectively, 25, 28, 31, 33, and 33 pounds of 
 water per cubic foot. If a given quantity of water passes down 
 through a depth of saturated subsoil of the river terrace in 100 
 minutes, it would take about 120 minutes for the same quantity of 
 water to go down through the same depth of the saturated subsoil of 
 the light truck land. This probably explains a matter of common 
 observation and experience, that crops on light sandy lands are more 
 
286 MARYLAND AGKICULTUEAL 
 
 injured in excessive wet seasons than crops on heavier soils. The 
 excess of water cannot be removed so fast by the light lands, when 
 saturated, as in the heavier soils. 
 
 There are other interestinej lines of thought, and explanations of 
 other matters of common observation and experience, suggested bj 
 this line of i-easoning, which may be followed out at another 
 time as the limits of this report allow of only a concise narrative 
 account of the work and a very general statement of the appli- 
 cation of the results. 
 
 X. The Improvement of Soils. 
 
 When we consider that desserts are barren only from the lack of 
 water and that where water is supplied they become fertile and pro- 
 ductive as other lands; and when we consider the immense crops 
 raised in dry and arid countries by irrigation as well as the difference 
 in the yield of, crops in our own state, in wet and in dry seasons, and 
 other evidences which will be published at another time, we are 
 forced to the conclusion that vegetation is very largely dependent for 
 its developement and growth upon a proper water suppl}'', and that 
 the whole art of cultivation and manuring is based upon the possible 
 control of the water supply within the soil. 
 
 We have shown the principles upon which this control is based ; we 
 come now to an application of these principles to the improvement of 
 soils. 
 
 The agricultural lands of this state have generally good surface 
 drainage. They have a small quantity of organic matter which is 
 fairly uniform in amount in the soils of the different soil formations. 
 If such a soil is shown by a mechanical analysis to have not less than 
 ten thousand million grains per gram, it has the structure, or frame 
 work, for a good wheat soil and should be classed as such. If it does 
 not produce good wheat crops, or if it has deteriorated from a more 
 fertile condition, there may be some change in the structure of the 
 soil through a change in the arrangement of the soil grains. 
 
 The case must be studied as a physician considers the condition of 
 a sick person ; a diagnosis must be made to determine the cause of 
 the trouble. The symptoms both of the soil and of the crops must 
 be carefully studied. If the soil is rather close and too retentive of 
 moisture, the plants are large and sappy and give a small yield of 
 fruit or seed in proportion to the size of the plant and the amount of 
 
EXPERIMENT STATION. 287 
 
 food material gathered b}' the plant from the atmosphere and soil. 
 The crop is also inclined to be late it maturing. 
 
 If the soil is dry and leachy, the plants are small and give a small 
 yield, but the yield is relatively larger in proportion to the food 
 material that lias been stored up. 
 
 Other symptoms, besides this relation of the yield of grain and 
 fruit to the size of the plant, that is, to the amount of food material 
 stored up by the plant, offer evidence as to the condition of the .soil 
 and the changes needed for its improvement, such as the vigor of the 
 plant, the way it develops and grows, the diseases and insect ravages 
 to which it is subject, and the influence of wet and dry seasons on 
 the crop production. 
 
 The cotton crop at the South is very sensitive to these conditions of 
 environments. The wheat crop more readily adapts itself to the con- 
 ditions under which it is grown, and is, therefore, not so sensitive or 
 reliable for showing up these soil conditions. 
 
 There is need of an instrument, or a method, to show the actual 
 rate with which water moves both up and down within the soil in 
 its natural position in the held, and such a method must be devised, 
 for the information is of great importance. 
 
 It has been shown how the relative rate of circulation of water 
 may be calculated from the mechanical analysis of the soil. If this 
 calculated rate could be compared with the actual rate of circulation 
 in the soil in the held, it would indicate the relative arrangement of 
 the soil grains, so that if we had such a method there would be no 
 such necessity for studying the symptoms of the plant to tell in what 
 direction, and how far, the conditions in a soil have departed from 
 the typical conditions required by a given crop, or natural to the soil 
 formation. 
 
 If the rate of circulation of water within the soil is shown, by 
 actual observation or by its effect upon plants, to be slow^er than the 
 rate calculated from the mechanical analysis, and slower than the rate 
 of circulation in the typical soil for that crop, the texture of the soil 
 may be changed by changing the arrangement of the soil grains. 
 The smallest grains may be drawn closer to the larger ones, making 
 some of the spaces larger and others exceedingly small. Lime, 
 kainite and phosphoric acid seem to have this effect, as their con- 
 tinued use makes the soil more loamy, looser in texture, and less 
 retentive of moisture. 
 
288 MARYLAND AGRICULTURAL 
 
 Many of our agricultural lands need improvement in the other 
 direction, they need to be made closer in textnre and more retentive 
 of moisture. We have found that ammonia, the caustic alkalies, 
 carbonate of soda, and probably many other substances, possibly 
 organic substances in general, tend to prevent this flocciilation and to 
 push the smaller grains further apart, making the spaces within the 
 soil of a more uniform size and thus retarding the rate of circulation 
 of the soil moisture. We cannot say what practical value this 
 will have in its application to agriculture until more work has been 
 done. 
 
 When a solution of organic matter comes in contract with lime, 
 kainite, acid phosphate, and with certain soils, the organic matter is 
 precipitated from solution in light, bulky masses, and these masses 
 may fill up the spaces within the soil with solid matter which not 
 only retards the rate of circulation of water downward by gravity, 
 but, by increasing the extent of water-surface within the soil, it also 
 assists in pulling water up from below. 
 
 If so much organic matter is added to the soil that it cannot be 
 curdled or precipitated from solution, it may be injurious in the soil 
 by reducing the surface tension of the soil moisture, the force which 
 draws the water to the plant as needed. The judicious use of lime, 
 kainite or acid phosphate, along with the organic matter, will insure 
 the precipitation of the organic- matter from solution and thus give a 
 value to the application which it would not otherwise have had. 
 
 This gives a value to stable manure, out of all proportion to the 
 amount of plant food which it contains. Lime, also, either alone or 
 when acting with, organic matter, has a distinct value for all classes of 
 land. The nitrogenous matters in the stable manure, and in other 
 organic matters, would determine the value as a fertilizer, for it is 
 only the nitrogenous compounds which are so easily precipitated from 
 solution by the mineral matters of the soil and of fertilizers. If the 
 carbohydrates, such as starch, sugar and woody fibre, could be as 
 readily precipitated from solution in light, bulky masses, by lime and 
 the mineral matters of the soil, then sawdust or other organic refuse 
 containing little nitrogen, would have nearly the same fertilizing 
 value as the more expensive nitrogenous materials. 
 
 The whole history of plat experiments shows that it is not the plant 
 which is to be manured for, but the soil conditions must be changed 
 to produce the plant. 
 
EXPERIMENT STATION. 289 
 
 The corn plant on one soil requires potash, on another soil, phos- 
 phoric acid, on another soil, nitrogen, and again on another soil a com- 
 bination of two or more of these fertilizers. On the whole, there is 
 no such fertilizer in our State for wheat as lime, used alone or acting 
 with organic matter. 
 
 Plat experiments frequentlj^ give a larger yield when lime, 
 salt or plaster is used, and even when nothing at all has been 
 added to the soil, than when the more expensive plant foods 
 have been used. Especially when acid phosphate or potash has been 
 used alone, the yield is often smaller than where nothing has been 
 added to the soil. 
 
 Under ordinary conditions, our crops do not require special plant 
 foods, but they all have somewhat different habits of growth and 
 development and can best gather food under somewhat different 
 physical conditions. We have seen how these different fertilizing 
 materials cliange the physical conditions in the soil. 
 
 This opens up a new and wide field for investigation in the study 
 of the physical conditions of the soil in their relation to plant growth 
 and developement, and the effect thereon of the different fertilizers 
 and manures. It will be through this study that the true theory of 
 fertilization will be seen, and an interpretation and added value be 
 given to the immense amount of chemical data, which has accumu- 
 lated, relating to the soil. 
 
 Correction: — Through an oversight, part of the explanation of the phenomenon 
 of flocculation on page 258 was transposed. It should read as follows : If the 
 potential of the surface particle of water is less than of a particle in the interior of 
 the mass of liquid, there will be surface tension, and the two grains will come 
 together and be held with some force, as their close contact will diminish the num- 
 ber of surface particles in the liquid. If, on the other hand, the potential of the 
 particle on the surface of the liquid is greater than the potential of a particle in the 
 interior of the liquid mass, the surface will tend to enlarge, and the grains of clay 
 will not come close together, as their close contact will diminish the number of 
 surface particles in the liquid around them. 
 
 M. W. 
 
 APPENDIX. 
 
 Since the main part of my report was written, I have been able to 
 secure the services of Mr. F. P. Veitch and Mr. J. B. Latimer, 
 graduates of the class of 1891 of the Agricultural College. Mr. 
 Yeitch has completed the mechanical analysis of our type subsoils, 
 which enables me to present the results here, with a short discussion. 
 
 The mechanical analysis of these type subsoils, given in Table 13, 
 is based upon the "line earth," or material smaller than 2 ')mn. in 
 
290 
 
 MARYLAND AGRICULTURAL 
 
 QJ m —. i rH ,-1 
 
 
 N 
 
 
 
 1— I 
 
 00 
 
 
 en 
 
 c> 
 
 CSl 
 
 
 
 03 
 
 
 
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 CO 
 
 
 S-t 
 
 0) 
 
 
 00 
 
 <D 
 
 o 
 
 w 
 
 r» 
 
 > 
 
 C3 
 
 >H 
 
 N 
 
 « 
 
 
 H 
 
 
 
 
 fe 
 
 
 
 r1 
 
 o 
 
 o 
 
 
 OJ 
 
 
 00 
 
 
 ^ 
 
 1— I 
 02 
 
 N 
 
 
 ^ 
 
 K-l 
 
 
 
 
 h-1 
 
 
 
 ^" 
 
 <1 
 
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 ^ 
 
 
 
 O 
 
 o1 
 
 
 
 
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 00 
 
 
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 ^ 
 
 
 
 
 
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 N 
 
 
 
 w 
 
 
 
 
 1-1 
 
 
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 P5 
 
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 C 
 
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 < 
 
 C~ 
 
 Oi 
 
 
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 N 
 
 
 c3 
 
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 "^ 
 
 tH 
 
 .-H 
 
 CD 
 
 C-) 
 
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 3 T-H 
 
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 CO 
 
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 'St 
 
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 n-H 
 
 5 O 
 
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 30 
 
 CI 
 
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 1 oS 
 
 TI< 
 
 3 GO 
 
 O 
 
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 OI 
 
 
 
 
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 CD 
 
 
 
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 3 CO 
 
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 3 Cl 
 
 <M 
 
 
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 00 
 
 
 
 
 
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 fe o 
 
EXPERIMENT STATION.' 291 
 
 diameter. Three of these subsoils were not tlioroughly disintegrated^ 
 bnt contained small fragments of rock, which were separated out and 
 weighed, the remaining line earth being used for the mechanical 
 analysis. The samples contained the following per cent, of coarse 
 and of fine material. 
 
 290 238 289 
 
 Oriskany. Catskill. Shales. 
 
 Coarser than 2 mm. 5.80 21.28 17.23 
 
 "Fine earth" 94.20 78.72 82.77 
 
 "We have not, as yet, attempted to study the efEect of these frag- 
 ments of rock upon the relation of the soils to the movement of 
 water, but have confined ourselves to the simpler study of soils hav- 
 ing no coarse fragments, and we will, therefore, disregard tliis coarse 
 material for the present, and treat the soils as though composed only 
 of the fine earth. It may well be, that in some localities disintegra- 
 tion has gone further than where these samples were taken, and that 
 these same soil formations there contain no coarse fragments of the 
 undecomposed mck. Our results should apply directly to such a soil. 
 
 1 692 000 000 
 6 868 000 000 
 
 8 258 000 000 
 
 9 154 000 000 
 10 358 000 000 
 11684 000 000 
 14 736 000 000 
 14 839 000 000 
 
 18 295 000 000 
 
 19 638 000 000 
 
 24 653 000 000 
 
 Table 11 gives the approximate number of grains of sand and clay 
 in one gram of these type subsoils, and the results conlirm what has 
 been stated before, that the soils thus arranged are in the order of 
 their relative agricultural value. 
 
 Table U: 
 
 — Approximate Number 
 
 
 Subsoil. 
 
 276. 
 
 Pine barrens. 
 
 284. 
 
 Truck. 
 
 286. 
 
 Tobacco. 
 
 290. 
 
 Oriskany. 
 
 280. 
 
 Wheat. 
 
 278. 
 
 River terrace. 
 
 282. 
 
 Triassic red sandstone. 
 
 238. 
 
 Catskill. 
 
 289. 
 
 Shales (Hamilton, &c.) 
 
 288. 
 
 Helderberg limestone. 
 
 .... 
 
 Trenton chazy limestone, 
 
292 MARYLAND AGKICULTURAL 
 
 The Oriskany formation is of very small agricultural importance, as 
 it has such a small area in the State, occurring in narrow belts,' the 
 widest being hardly more than a mile across. It has a place in the 
 table between the tobacco and wheat soils of Southern Maryland. 
 
 The Triassic i-ed sandstone and the Catskill formations are shown 
 to have about the same structure. The soils themselves are very 
 similar, and, except for their distinct geological and geographical 
 positions, they should be grouped as a single soil type. The Catsldll 
 formation covers a considerable area in the valley between Sideling 
 Hill and Town Hill Mountains, and again between the Great Savage 
 Mountain and the Meadow Mountain, wath a very narrow belt near 
 Dan's Mountain, between Mt. Savage and Cumberland, wdiere our 
 single sample of the formation was obtained. This is an important 
 soil formation, which should be more carefully studied, and of which 
 more samples should be taken. From the general appearance of the 
 land, as seen from the train in passing, there does not seem to be as 
 . much undecomposed rock in the soils of these wider areas as is con- 
 tained in the sample, which is given here. I should estimate that 
 there are about 32i) square miles of this Catskill formation in West- 
 ern Maryland, and about the same area of the Triassic red sandstone 
 to tlie north and south of the Frederick Valley. 
 
 The Hamilton and Chemung shales have their widest exposure 
 around Hancock and on either side of the Polish Mountain, covering 
 perhaps 1-25 square miles. The Clinton and ^Niagara shales occur in 
 very narrow ridges, giving a much smaller exposure than this. The 
 mechanical analysis of the type sample of these formations gives 
 39.36 per cent, of "clay," or, approximately, eighteen thousand mil- 
 lion grains per gram. The samples contained many small fragments 
 of rock, so far disintegrated that they went to pieces at once between 
 the iingei"s, or when they were gently rubbed with the rubber pestle 
 under water. As these fragments would so readily fall to pieces in 
 handling, much of this was classed as "fine earth," and only 17.23 
 per cent, could be separated out as coarse material. I think that this 
 type has not its true agricultural place in the arrangement of these 
 tables, as the grains of sand and clay have evidently not the same 
 arrangement as in a soil where the disintegration has been more com- 
 plete and the grains are more evenly distributed. It was stated in a 
 previous section tliat these soils were naturally poor, but had 
 good body and could be improved. This table shows that they 
 have good body, and it remains now to show how the actual 
 conditions differ from the best conditions wdiich should prevail in this 
 type soil, and how the soils can best be improved. In other States, 
 where these shales are more thoroughly decomposed, they make some 
 of the most fertile lands. They should have a value not far below 
 that of the Helderberg limestone. 
 
 There is but a small area of the Helderberg limestone in this State, 
 occurring in several narrow belts crossing Western Maryland. The 
 
EXPERIMENT STATION. 293 
 
 area of the whole formation is only a few square miles in extent. 
 The formation ^ives a very fine grass and wheat soil. In the calcula- 
 tions which follow, I have used the Helderberg limestone as the 
 strongest soil, and the best for grass and wheat of any of the types, 
 not having sufficient samples from the Trenton limestone to establish 
 a satisfactory type sample. 
 
 I must again urge, as in a former paragraph, that the number of 
 grains of sand and clay give only the skeleton structure of the soil, 
 and that this may be so filled in with organic matter as to greatly 
 modify the physical properties of the soil. The amount of organic 
 matter is assumed to be fairly constant for the different types, and is a 
 matter of more importance in the study of local soils. It is important 
 also to remember tliat the structure of the soil, and its relation to the 
 circulation of water, is dependent not only upon how many grains there 
 are per gram, but upon how these grains are arranged. In our calcu- 
 lations, we have assumed that they have the same mean arrangement 
 in all the type soils ; but this is evidently not so in regard to local 
 soils, for we have suggested that the deterioration of soils is due 
 largely to a change in the arrangement of the soil grains, changing the 
 relation of the soil to the circulation of water. These type samples, 
 however, represent more than this, for they are selected to represent 
 the average, natural condition of these great soil formations. 
 
 The average, natural arrangement of the grains in these great soil 
 formations must be determined to give an additional basis of com- 
 parison between the different types, but especially for the comparison 
 of local soils, which may have departed, in one way or another, from 
 the type conditions, through a re-arrangement of the grains of sand 
 and clay. This is important in the study and classification of local 
 soils. 
 
 It is quite possible to conceive of a brick clay or a tight pipe clay, 
 having no more grains per gram than this Helderberg limestone. If 
 a few drops of caustic ammonia was applied to the Helderberg soil, 
 through which a certain weight of water was passing in a hundred 
 minutes, the grains of soil would be re-arranged, and it would take 
 several thousand minutes for the same amount of water to pass. On 
 the other hand, a little lime water would make the soil more l@amy, 
 and hasten the rate of movement of water. "We have thus a loam 
 soil, a good clay soil and an impervious pipe clay, out of the same 
 soil, by a simple re-arrangement of the sand and clay. The arrange- 
 ment of the grains has, therefore, an important bearing on tlie physi- 
 cal properties of the soil, but this is largely dependent upon local 
 causes, which modify the conditions in the original soil formation. 
 
 From the results in these tables it would seem that the subsoil of 
 good grass land would have not less than 30 per cent, of clay, or al)out 
 twelve tJioiisand million grains per gram, and good wheat land not 
 less than twenty per cent., or about nine thousand million grains per 
 gram ; ])rovided^ these grains have a certain mean arrangement and 
 
29i MARYLAND AGKICULTUEAL 
 
 that this skeleton structure contains an average amount of organic 
 matter. It mast be remembered that if either the arrangement of 
 the grains or the amount and condition of the organic matter departs 
 from the average condition of the soil, the plijsical condition of the 
 local soil will depart from the typical conditions of the soil formation. 
 These type subsoils have the following approximate extent of sur- 
 face area per cubic foot : 
 
 276. Pine barrens. 40 per cent, space. 23 940 square feet. 
 
 284. Truck. 45 " " . " 74 130 " " 
 
 286. Tobacco. ' 50 " " " 84 850 " " 
 
 290. Oriskany. 50 " " " 87 720 " " * 
 
 280. Wheat. 55 " " " 94 540 " " 
 
 278. Kiver terrace. 55 " " '' 106 200 '' " 
 
 282. Triassic. 55 " " " 127 000 " " 
 
 288. Helderberg limestone. 65 " " " 129 700 " " 
 238. Catskill. 55 " " " 133 300 " " 
 
 289. Shales (Hamilton, &c.) 60 " " " 142 700 " " 
 
 The practical bearing of these results has been quite fully set forth 
 in Section VIII. The Helderberg limestone has a place here before 
 the Catskill and the shales, because we have given it a high percentage 
 of empty space, higher perhaps than should have been given. It has, 
 of course, the highest percentage of surface area per unit weight of 
 any of these subsoils, but the larger amount of space lowers the per- 
 centage per unit volume of soil. 
 
 From the foregoing results, we have calculated the relative rate 
 with which a given quantity of water would pass through an equal 
 depth of these subsoils, under a constant force and with the same 
 amount of water (12 per cent.) in each subsoil, taking the subsoil of the 
 Helderbei'g limestone as a basis of comparison. 
 
 It would appear from results on next page that, with 12 per cent, of 
 water present in all the subsoils, it wall take only 8 minutes for a quantity 
 of water to pass through the subsoil of the pine barrens, which would 
 require 100 minutes to pass through the same depth of the subsoil of 
 the Helderberg limestone. It will pass through the subsoil of the 
 wheat land of the river, terraces in Southern Maryland in about 49 
 minutes. It will move down more readily in these lighter soils 
 from its own weight, but, as I have urged in a previous section, a 
 given quantity of water could not be raised so readily to supply the 
 needs of a growing crop, for there would be less exposed water-surface 
 to contract, that is, there would be less force to pull it up. 
 
EXPERIMENT STATION. 
 
 295 
 
 No. 
 
 Soil. 
 
 
 Space 
 
 
 Water-content. 
 
 Relative 
 Time. 
 
 276. 
 
 Pine barrens. 
 
 
 40] 
 
 3er 
 
 cent. 
 
 12 
 
 3er 
 
 cent. 
 
 8 
 
 284. 
 
 Truck. 
 
 
 45 
 
 
 
 12 
 
 
 
 21 
 
 286. 
 
 Tobacco. 
 
 
 50 
 
 
 
 12 
 
 
 
 33 
 
 290. 
 
 Oriskany. 
 
 
 50 
 
 
 
 12 
 
 
 
 35 
 
 280. 
 
 Wheat. 
 
 
 55 
 
 
 
 12 
 
 
 
 45 
 
 278. 
 
 Kiver terrace.- 
 
 
 55 
 
 
 
 12 
 
 
 
 49 
 
 282. 
 
 Triassic. 
 
 
 55 
 
 
 
 12 
 
 
 
 56 
 
 238. 
 
 Catskilk 
 
 
 55 
 
 
 
 12 
 
 
 
 58 
 
 289. 
 
 Shales (Hamilton, 
 
 &c.) 
 
 60 
 
 
 
 12 
 
 
 
 81 
 
 288. 
 
 Helderberg limestone. 
 
 65 
 
 a 
 
 
 12 
 
 
 
 100 
 
 I liave calculated the amount of water which should be present 
 in these different subsoils for the rate of movement, due to a con- 
 stant force, to be the same as in the subsoil of the Helderberg 
 limestone, containing 12 per cent, of water. 
 
 No. 
 
 Soil. 
 
 
 
 Space. 
 
 Water-content. 
 
 Relative 
 Time. 
 
 276. 
 
 Pine barrens. 
 
 
 40 
 
 per 
 
 cent. 
 
 5.3 
 
 per 
 
 cent. 
 
 101 
 
 284. 
 
 Truck. 
 
 
 45 
 
 
 
 7.2 
 
 
 
 101 
 
 286. 
 
 Tobacco. 
 
 
 50 
 
 
 
 8.4 
 
 
 
 102 . 
 
 290. 
 
 Oriskany. 
 
 
 50 
 
 
 
 8.6 
 
 
 
 101 
 
 280. 
 
 Wheat. 
 
 
 55 
 
 
 
 9.4 
 
 
 
 100 
 
 278. 
 
 River terrace. 
 
 
 55 
 
 
 
 9.6 
 
 
 
 100 
 
 282. 
 
 Triassic. 
 
 
 55 
 
 
 
 10.0 
 
 
 
 101 
 
 238. 
 
 Catskill. 
 
 
 55 
 
 
 
 10.1 
 
 
 
 100 
 
 289. 
 
 Shales (Plamilton, 
 
 &c.) 
 
 60 
 
 
 
 11.2 
 
 
 
 100 
 
 288. 
 
 Helderberg limestone. 
 
 65 
 
 
 
 12.0 
 
 
 
 100 
 
 The relation of these different subsoils to water is as different as in 
 the artificial conditions in green house culture. The difference is 
 amply sufficient to account for the distribution of plants and for the 
 known relations of these different soils to plant growth and develop- 
 ment. 
 
 I have also calculated the relative rate with which water would 
 move, under a constant force, through these different subsoils, if all 
 the space within them was filled with water. 
 
296 MARYLAND AGKICULTUEAL EXPEKIMENT STATION. 
 
 
 
 
 
 
 
 
 Relative 
 
 No. 
 
 Soil. 
 
 
 
 Space. 
 
 Water- 
 
 content. 
 
 Time. 
 
 276. 
 
 Pine barrens. 
 
 
 
 40 per cent. 
 
 20.10 per 
 
 cent, (sat.) 
 
 74 • 
 
 284. 
 
 Truck. 
 
 
 
 45 " " 
 
 22.41 " 
 
 " 
 
 141 
 
 286. 
 
 Tobacco. 
 
 
 
 50 " " 
 
 27.42 " 
 
 " 
 
 121 
 
 290. 
 
 Oriskany. 
 
 
 
 50- " " 
 
 27.42 " 
 
 " 
 
 130 
 
 280. 
 
 Wheat. 
 
 
 
 55 " " 
 
 31.55 " 
 
 " 
 
 109 
 
 278. 
 
 River terrace. 
 
 
 
 55 " " 
 
 31.55 " 
 
 " 
 
 119 
 
 282. 
 
 Triassic. 
 
 
 
 55 " " 
 
 31.55 " 
 
 " 
 
 137 
 
 238. 
 
 Catskill. 
 
 
 
 55 " '< 
 
 31.55 " 
 
 " 
 
 140 
 
 289. 
 
 Shales (Hami 
 
 Iton. 
 
 , &c.) 
 
 60 " " 
 
 36.14 " 
 
 " 
 
 123 
 
 288. 
 
 Helderberg li 
 
 mestone. 
 
 65 " " 
 
 41.22 " 
 
 u 
 
 100 
 
 It will be seen that the amount of space assigned to these different 
 soil formations, has an important bearing on the relative rate with 
 which water will move within the different soils. The coarser text- 
 ured soils have less space and will contain less water than the clay 
 soils. The subsoil of the truck land has only 45 per cent, of space, 
 and will hold but 22.41 per cent, by weight of water, when this space 
 is completely filled. The subsoil of the Helderberg limestone has 65 
 per cent, of space, and will hold 41.22 per cent, by weight of water, 
 or nearly twice as much as the truck land. When the soils con- 
 tained only 12 per cent, of water, a quantity of water would 
 move through the truck land in 21 minutes, which would require 
 100 minutes to pass through the subsoil of the Helderberg lime- 
 stone. When, however, these soils are taxed to their utmost, 
 it will take 141 minutes for a quantity of water to pass through the 
 truck land, which would go through the limestone subsoil in 100 
 minutes. As suggested in a previous section, this undoubtedly ex- 
 plains a matter of common observation and experience, that crops on 
 these light lands are more injured by excessive wet seasons than crops 
 on heavier soils. 
 
 These calculations of the relative rate with which water will move 
 within these different subsoils, are based solely upon the skeleton 
 structure. The influence of the organic matter is not considered, and 
 the soil grains are assumed to have the same mean arrangement. 
 These two factors, the amount of organic matter and the arrange- 
 ment of the soil grains, are probably nearly alike under the normal 
 conditions which prevail in these great soil formations ; but if they 
 have not relatively the same effect in the different soils, they will 
 undoubtedly make the difference in the relation of these soils to the 
 circulation of water, still wider than the values we have assigned. 
 Each of these factors requires a distinct line of investigation, and this 
 is necessary to the practical use and application of this work. 
 
I.IBRA.IIY of 
 
 iMiassaciiiiset' 
 
 OCT 22 1910 
 
 A-grioTilt-arsu 
 
 THE SOIL, o°^-s« 
 
 CONSIDERED AS A 
 
 SEPARATE AND DISTINCT DEPARTMENT OF NATURE, 
 
 ROBERT. SEER ELL.W 00 0, 
 
 Corresponding Member of the National Institute. 
 
 WASHINGTON, MARCH, 1850. 
 
 The most palpable source of nutrition to all created beings was sup- 
 posed by the ancients to possess the attributes of vitality ; it was there- 
 fore an amiable weakness on their part to personify the Earth, and to 
 hold her in pecaliar veneration. Modern science has banished this beau- 
 tiful sentiment from its stern philosophy, but it can never invalidate the 
 fact that there are certain ingredients of the soil (whatever be their 
 origin) which claim intermediate rank between matter in such states of 
 combination as the chemist can produce by synthesis, and the lowest 
 specimens of vegetable organisms : neither has it yet successfully proved 
 that the same elements in other shape than the organic salts of humus 
 contribute with equal efficiency to the luxuriance of vegetation, although 
 there is evidence in volclmic and other localities to show, that an excess 
 of either free carbonic acid gas, or ammonia, or water, even when the 
 other minerals present suffice for the wants of plants, is injurious to the 
 highest degree. A greater proportion than at present of those gases and 
 vapours in the atmosphere, and consequently in the soil, may have favored 
 the earliest denizens of our globe : those tribes have now nearly passed 
 away, or their constitution has been modified with modifications of cli- 
 mate, &c. 
 
 A just appreciation of fossil organic remains has elicited a probable 
 trulh, that function and organization proceed through both kingdoms of 
 nature by parallel lines of advancement, observable since the different 
 periods of the world at which they respectively commenced their exist- 
 ence. It would seem as if some general law, harmonizing with the 
 earth's progress in its physical Capacity, governed the succession of these 
 products, an idea which is further supported by their gradual develop- 
 ment at the present day from the germinal to a perfect state. We should 
 also bear in mind the remarkable fact, that animals and vegetables are 
 blended together so as to render any attempt to define their distinguish- 
 
 ^ /^n 
 
2 
 
 ing properties utterly futile. Vegeto-animals have been fully recognised 
 by naturalists ; and we are next led to inquire whether the soil, forming 
 a connection between organized and unorganized matter, partakes of a 
 vegeto-minerdl character in the highest acceptation of the term. 
 
 The animal department, although indebted for its growth and prime 
 condition to azotized aliment approximating more or less in its nature 
 the tissues themselves, borrows, from vegetables especially, hydro-car- 
 bonaceous substances of a less complex composition, a portion of which 
 is converted into fat, another portion is directly oxidized and excreted, 
 while a third is presumed, in the case of the lowest animals, to be con- 
 vertible by means of ammonia into gelatine, &c., their integuments cor- 
 responding with those of plants as surfaces absorbent of nourishment, 
 sufficiently at least to establish a close relation between both races in 
 this respect as well as in their both inhaling oxygen.* Again, the vege- 
 table department in its highest range, although dependant upon rich 
 mould or organic manures for its most efficient support, (as man and 
 some other animals are upon flesh,) draws from the atmosphere elements 
 convertible into cellulose, &c., indicating the claims of animals upon 
 vegetables, of vegetables upon the soil, and, as I shall endeavor to show, 
 the ultimate dependance of the soil upon the atmosphere. Nature evi- 
 dently proposes more than one resource for the maintenance of her crea- 
 tures ; and unity of design, which pervades the works of creation, would 
 suggest that, although the soil receives its most unequivocal accessions 
 from the debris of plants, it nevertheless allows the crude materials of 
 air to circulate within its pores, and to form more notable combinations. 
 Animals, vegetables, and the soil are constituted in large proportion of 
 particles, which have possessed, but which no longer retain, the usual 
 characteristics of life — particles, be it observed, which threaten to resolve 
 themselves into simpler forms, unless the tendency to .disintegration be 
 
 *The oxidation of the hydrocarburets is generally believed to liberate calorie in living bodies as 
 a primary result, but I respecifullv maintain that it, in the first instance, causes the surrender of 
 electricity which w^as previously combined ; heat consequently bigjomes a secondary effect of an 
 altered consistency or composition in solids or fluids, whereby their specific capacity for caloric 
 is aflfected. The temperature of animals is exaggerated by physical exertion, which causes the 
 contraction of muscles and a more rapid circulation of the blood. A large portion of their food is 
 already combined with oxygen in the proponion to form water ; no heat is therefore evolved from 
 this source, and the separation of free water from their surfaces in the shape of vapour produces a 
 reduction of temperature perhaps equivalent to the heat generated by the conversion of venous into 
 arterial blood. The slow reactions between highly constituted substances may be identical in a 
 chemical point of view with ordinary cases of combusti.m, but the results very difl^erent ; the 
 amount of heat liberated being proportionate to the greater or less competency of conducting 
 media to carry off the electricity set free, or of other contiguous molecules in the circulation or 
 elsewhere to appropriate that imponderable by forming new combinations. And here I may be 
 permitted to add, that if the solution of a simple metal in the voltaic apparatus liberates a force 
 which, on being conducted by a special arrangement of wire around an enclosed bar of iron, mag- 
 netizes it, a fortiori the resolution of more complex particles, such as those contained in the ani- 
 mal circulation, might be supposed capable of contracting (magnetizing) a muscle enclosed with- 
 in a network of conducting nervous filaments. A ganglion is the voltaic apparatus^ certain con- 
 stituents of the blood electrolytes, the motor and sensitive nerves conducting media, and the mus- 
 cle, which is insulated by cellular matter and ligament, a magnet. The contr.action of a muscle 
 or a congeries of muscles would not necessarily diminish the volume of their mass, because their re- 
 duction of size only tends to enlarge the capacity of the surrounding cellular substance ; free in- 
 gress is therefore allowe d to the blood between the fibres, and cmisequently greater efficiency 
 produced in the parts. 
 
3 
 
 counteracted by a force of an opposite kind. The soil possesses no evi- 
 dence of organization either in mass or in detail ; but organization may 
 mark grades of development without being indispensable to characterize 
 living matter. Nothing can be more indefinite than even the essential 
 properties of life. Can physiologists determine at what precise moment 
 the vital principle is surrendered by a piece of muscle cut from the leg 
 of a healthy animal ? The separation of a part merely shortens its term 
 of existence by destroying perhaps the faculty of self-preservation or re- 
 production. Where then shall we find the first link in the self-supporting 
 chain of vital products? Are we to consider the vesicles or cells which 
 the microscope discovers almost everywhere on the earth's surface as ex- 
 hibiting the simplest manifestations of life, or may we refer its rudiments 
 to the corpuscles of blood, or to certain constituents of sap ? 
 
 I propose to- regard the soil as a creature sui generis, sustaining 
 living bodies whilst it is itself sustained by them. Its proportions are 
 limited by the means of increment placed at its disposal. If the 
 natural history of soil be studied, we find that although it may in- 
 crease enormously under certain conditions, and although its term of 
 maturity may be prolonged to an apparently indefinite extent, its ulti- 
 mate dissolution, in whole or in part, is a matter of as much certainty 
 as the lapse of ages. Organized bodies, however, display their power 
 of increase more particularly in their progeny, which represent the pa- 
 rent in an enlarged individuality. The soil, likewise constituted, as I 
 shall presently endeavor to show, of many individuals of different char- 
 acter, is capable of propagating its kind by a quasi-fissiparous process — 
 that is to say, a portion of veritable mould being isolated from the main 
 body and placed in a favorable situation, exerts a quickening influence 
 upon surrounding matter of elemental identity: mould, consequently, 
 either enlarges in bulk itself, or gives bulk to vegetables, just as vegeta- 
 bles, during their growth, either enlarge in bulk themselvs, or give bulk 
 to animals which feed upon them. It may be further urged, as a gene- 
 ral proposition, that animals, plants, and the soil, increase and multijsly 
 in co-ordinate ratios, and that, with the continued addition of light, a 
 much greater mass of matter will be engaged in the enjoyment of more 
 exalted faculties, either in an organized or semi-organized shape. 
 
 Aboriginal soil, then, may be attributed to the rays of the sun co-ope- 
 rating with physical changes of certain universally diffused substances, 
 which I shall presently mention — changes of form, consistency, and po- 
 sition, capable of impressing the heterogeneous residue with new affini- 
 ties. We, however, regard, as chiejiy instrumental, at the present day, 
 in the generation of humus de novo from carbonic acid and water, the 
 forces liberated by already existing humus, or by materials of higher 
 grade in the act of decomposition — forces identical with those emitted 
 from the luminous worlds around us. 
 
 Commencing with the lowest grade of progressive developments, we 
 submit for consideration : first, whether ulmin and other semi-organized 
 substances were not originally, and are not still, produced from carbonic 
 acid and water at the expense of ammonia which becomes decom- 
 posed in the ground by means of oxygen, nitrogen being liberated upon 
 the same terms which vegetables prescribe for themselves during an an- 
 
alogous process of transformation.* Secondly, whether the disintegra- 
 tion of those hydrocarburets which are formed in vegetables from ulmin, 
 such as starch, gums, oils, &c., does not promote the formation of various 
 azotized proximate principles, when ammonia, sulphur, phosphorus, and 
 some few other minerals, are present. Lastly, whether tl^e dissolution 
 of these proteine and allied compounds into less complex forms, or into 
 their ultimate elements, does not generate cellulose, &c. The idea on 
 which we particularly insist is, the reluctance on the part of bodies, 
 whether organized or unorganized, to allow their constitutional forces to 
 exhaust themselves by their component materials becoming resolved 
 into simpler combinations, as long as contiguous matter evinces the dis- 
 position of assuming an identical character or an equivalent complexi- 
 ty of constitution. For this reason, the same forces which enter into 
 the constitution of vegetables are apparently transmitted from one gene- 
 ration to another. But, on the other hand, it |nust be confessed that^ 
 were it not for the incessant appropriations of the luminous element by 
 the surface materials of our globe, no further progress in the quantity 
 or quality of chemico-vital phenomena could be anticipated. 
 
 It would likewise be unreasonable to expect the occurrence of these 
 spontaneous formations of soil, where the want of indispensable pre- 
 requisites prohibits what would be an ordinary train of events in more 
 favored regions. The fixed alkalies and - a - lkaleidg , in moderate quantity, 
 might expedite the process, and yet the same bases, or ammonia, or 
 water, in excess, effectually prevent it. To consider them as tending 
 to break up, under all circumstances, rather than to superinduce more 
 complex relations of matter, would be to adopt an error equivalent with 
 considering oxygen an element of universal destruction. 
 
 Viewed solely as an accumulation of dead or effete materials, the 
 ground presents a melancholy picture of desolation, but as a thing of 
 life it ofiers eminent support to the doctrine of development. As soon 
 as a fit habitation was prepared for land-animals and plants, they each 
 in the fulness of time entered on their career. There is an aptitude in 
 this arrangement, and no less probable is it that the first and simplest 
 forms of living matter derived their forces from existing substances of 
 lower degree in complexity, and that the light of heaven co-operated 
 then, as it does now, in the glorious consummation. Water-plants flour- 
 ished long before dry land appeared ; these must have subsisted upon 
 gases and salts dissolved in the ocean, and their debris became the source 
 of much primeval soil. This admission by no means militates against 
 the proposition that semi-organized compounds, constituting humus, may 
 also be formed in Nature's laborator}'' by a direct union of the elements 
 concerned, the most obvious cause of a primary character being the 
 redaction of ammonia, or its transformation, into water and nitrogen, 
 by means of oxygen. Whether other compounds be formed in the soil, 
 such as nitrates, which are due to progressive as well as retrograde re- 
 
 * It may be observed that the gaseous effluvia (excretions proper) respired by the leaves of 
 plants, are for the most part simple elements, as oxygen and nitrosren, which, on assuminsr the 
 aeritorm condition, give up the electricity previously binding them with solids in t*ie closest chemi- 
 cal relations ; their ioes of ibis force redounds to the benefit of plants by the consequent fixation 
 
 of <^arhon. 
 
t 
 
 actions, must depend upon dynamic contingencies. Holding these pre- 
 mises in mind, we are led to inquire whether the decomposition of semi- 
 organized compounds did not liberate the necessary forces and introduce 
 the lowest types of vegetable organisms, under conditions of the world 
 more favorable than at present, and w^hich we can scarcely now appre- 
 ciate.* These in turn becoming decomposed, and surrendering their 
 forces, may have forwarded new combinations of vegetable matter, until 
 we reach a period of the earth's history teeming with vital phenomena 
 familiar to us. 
 
 Germs, like nuclei of lesser note, may be identical, or nearly so, in 
 their ultimate or proximate elem.ents, and j-et differ in the proportions 
 of their combined imponderables. On this hypothesis the variety of 
 vegetables and even animals is divested somewhat of mystery ; the ele- 
 ments of nutrition being the same, the congenital forces which direct 
 the earliest vital movements in each particular genus or species deter- 
 mine their subsequent figure and organization. 
 
 Af er making due allowance for climate and the immediate effects of 
 solar irradiation upon the digestive powers of plants, we attach no little 
 importance to the shape in which their food is presented to the roots. It 
 is asserted by the modern school of Agricultural Chemists, that the or- 
 ganic food of plants is exclusively carbonic acid and ammonia dissolved 
 in water, and, of course, the force of life is esteemed the chief cause of 
 all organic changes of a progressive character. With us, on the con- 
 trary, it is contended, that the substances aforesaid could not possibly be 
 metamorphosed into higher compounds except by the addition of light, 
 or of forces identical with light, derived from organized and semi-orga- 
 nized materiel in the act of decomposition. It is well known, that no 
 manure is more acceptableto vegetables than their own decaying leaves, 
 or the ciebris of a higher class of plants; the explanation now offered 
 for this fact by authors entil led to our utmost respect, is, as stated above, 
 very sample ; but unfbriunately it leaves the solution of ulterior pheno- 
 mena hopeless. To attribute the more abstruse transmutations to a force 
 of life is tantamount to an abandonment of principles applicable to all 
 
 * These conditions have reference to termer bipolar niuvements of our eirth, not of an extra- 
 vagant, but of an exaggerated kind. 1 intend, on some future occ-asi m, lo submit reasons for the 
 belief tiiiit the sun is the imtiiei iate cause of the diurnal rotation of planets within the solar sys- 
 tem, and of their annual changes of position and presentation To be more explicit : if solar 
 rays be conipnund'-d, ;is I shall araiie, of repellent and aitiactive forces neutralized by their com- 
 bination ill light, and they be decomposed on the surface "f the ear h, (tins surface being a nnxt-d 
 one of soliils, liquids, and aeriform fluids ) we can understand how more of the calorific rays may 
 be delaiiif-d on the peripheral or outer portion of oui planet, and exert an influence there, while 
 the eleciric rays, for the most pari, pass on to ihe innermost surtai:e of the soliil crust, causing ad- 
 ditional layers to be precipitated from the central fluid mass. A tempo ary loss of equilibrium 
 thus occasioned hrtween the opposite sides of the sphere, produces a cenirifusial tendency in the 
 comparatively enlarged proximal surface, and a centripetal tendency in the d stal surface, which 
 becomes, each section of it for the instant, comparatively smaller than its antipod. We further 
 surmise that the earth has reached its present rate of movement and fxtent of bipolar osoillatioii 
 after considerable diminution id intensity in the North ;iiid Soutu hemispheres respectively, at 
 different epochs ; that the approaches to a more perlect Hqnilibrium^and conse'quent alterations of 
 climate from ihis cause^have been so gradual within the historic period as to have escaped the no- 
 lice of observers in tins hrlJ of science. I am not acquainted with any more plausible explanation 
 of the undoubted changes of level in the ocean s-ince the commencement of the ternary era, as evi- 
 denced by phenomena cf universal extent. 
 
6 
 
 physical changes for the production of which chemists are unable to con- 
 trol or concentrate the usual forces of matter. 
 
 Practical agriculturists will ke«irf?adi^g>>^i™Q^vi?fe<g;ycria^^ 
 
 that proximate principles must be, and in all cases are, reduced 
 before they can be absorbed by the roots. Because analytical chfmists 
 are unabje to dissolve by artificial means divers ingredients of humus, 
 it does not follow that a force derived from the voltaic movements of 
 contiguous living tissues is incompetent to do so; neither does it follow 
 that the constituents of the ascending sap vessels, or of animal chylife- 
 rous ducts, represent matter in its identical form as appropriated from 
 the prim® viae, or the soil, because the organic portions of food may 
 become attached to the presenting superficial tissues, before the force of 
 absorption separates and reduces them to other soluble ccmpounds as 
 found in the sap and chylous lymph. Although 1 have contended ihat 
 the precipitation of the solids in living bodies is mainly due to forces 
 derived from analogous materials, yet accretions to the roots of plants 
 probably occur at all seasons ; during spring and summer, however, the 
 foliage enjoys the privilege of appropriating aeriform ibod by means of 
 light, in addition to the forces borrowed from chemical and mechanical 
 reactions. 
 
 The usual articles of food correspond more or less with the tissues 
 which prevail in living bodies; hence it happens that, when referring to 
 animals, practical as well as speculative agriculturists lay great" stress 
 upon fibrin, albumen, phosphate of lime, &c.; when referring to plants 
 they formerly paid especial regard to the ordinary ingredients of humus, 
 and while pursuing that natural system (apart from the use of highly 
 stimulating manures, both organic and inorganic) were not troubled 
 with the treatment or the discussion of modern vegetable diseases. We 
 now suspect that just as there are peculiar principles in vegetables which 
 produce constitutional effects on animals, so there are in vegetable mould 
 of good quality combinations, not the result merely of decomposition, but 
 of direct union between the elements concerned; and that these vegeto- 
 mineraL varieties are of great importance, and define the nicer qualifi- 
 cations of soil and consequent character of plants cultivated therein. 
 The nervous matter of animals taken as food appears most likely to 
 sustain the nervous system and to promote the growth of neurine within 
 our own frames. No people feeding on vegetables exclusively has ever 
 attained eminence in the scale of nations ; not because neurine cannot 
 be formed from vegetable products, but because it cannot be so bounti- 
 fulljr formed. However much disposed the digestive apparatus may be 
 to reduce the ingesta to a homogeneous fluid, certain substances pass its 
 ordeal which may eventually give flavor, color, and other characteristics 
 to both animals and vegetables.* Public opinion has changed even in 
 respect to the elements which necessarily enter into the composition of 
 
 *A very general repugnance to truik raised upon night-soil exists, and I believe the objections 
 are to a certain extent valid. When vegetables are supplied with but a moderate amount of such 
 offensive manure, the probability is, that the digestive powers of the roots will completely alter the 
 character of such portions of food as are not assimilated by the soil ; or even if any is direcily 
 absorbed into the vegetable system, it is very rapidly decomposed and passed away. The case is 
 different when plants are rendered rank and stimulated by an excess of sewage; and it is from 
 such an unnatural and continuous process of forcing growth that we instinctively revolt. 
 
vegetables, but is still adverse to an ackriowledgeitient of any advaii* 
 tage derivable from the direct absorption of compounds highly endowed* 
 We cannot detect any absolute contrast in kind, such as is alleged to 
 exist, between the materials constituting the food of animals and vege- 
 tables, but simply a difference in amount of semi-organized and mine- 
 ral nutriment appropriated by the races respectively, corresponding with, 
 their functions and the complexity of their organisms. The fungous and 
 certain parasitic tribes establish this view of the subject almost conclu- 
 sively. Light is necessary to their health and welfare in different de- 
 grees ; its influence upon the functions of the human body being small, 
 there is the greater necessity for man's securing a full supply of protein- 
 ized aliment, and a moderate allowance of those vegetable stimulants 
 and beverages which administer to his gratification. It is in vain to 
 shut our eyes to what some may consider a humiliatory fact, that diet 
 essentially contributes to our physical and mental calibre. 
 
 From these miscellaneous data we infer that, although humus con- 
 sists mainly of well-known organic matter, it contains other substances 
 which perform an office entirely overlooked by agriculturists, and ad- 
 monishes them to reconsider the necessity of frequent rotations in crops, 
 so far as permanent improvement of the soil, and not immediate profit 
 by overtaxing its every capability, is concerned. The staples of a coun- 
 try, being ascertained by experience, may be encouraged by strictly res- 
 toring to the ground the refuse of those staples as specific manure. The 
 minute products referred to exhibit to my mind degrees of chemico- vital 
 complexity and corresponding differences in their physiological relations. 
 Not the least reason, perhaps, why the cerealia in particular are disin- 
 clined to extreme climates, or certain regions of country in even temperate 
 latitudes, is the same which prevented them from sooner gracing the bosom 
 of our earth, to wir, the want or insufficiency of appropriate semi-organ- 
 ized aliment. I may be told that grain has been successfully raised with- 
 out the least portion of humus, or any of this highly-extolled materia ali- 
 mentaria. We will join issue on this point, and await the verdict of good 
 and true men. who will we'gh the evidence of unexceptionable and long- 
 continued experiments; and if the cerealia do not degenerate or become 
 diseased, as potatoes have become, by the injudicious refinements of art, 
 I shall be agreeably disappointed. There cannot, I suspect, be too great a 
 supply of mould if there be also a proper proportion of mineral ingre- 
 dients, and silica in particular, to support the luxuriant stem. While 
 calculating the value of this class of plants we should be mindful not 
 to underrate the straw, whether as food, litter, or manure, for domestic 
 consumption. The tuber of potatoes has been perhaps over-stimulated 
 by unfermented organic manures not possessing a sufficiency of mineral 
 bases to ensure hardy germs,- whereas, what seems to threaten wheat is 
 an excess of inorganic elements over the organic, so as to render 
 it eventually more grain than stem ; and thus by forcing year after year 
 exuberant seed and a precocious progeny, we endanger the permanent 
 welfare of the plant. It is true that the grain crops are not cultivated 
 for their leaves or roots, as cabbages or turnips are,- but does not the 
 constitution of the germ depend upon the efficiency of the parent's whole 
 structure ? The evil is analegous to that of breeding in and in, whereby 
 
certain organs, peculiar products, and morbid tendencies are exaggera* 
 ted to the prejudice of the other parts and functions. Such a system 
 must terminate disastrously to animals and vegetables, as it operates 
 injuriously to the healthy condition and growth of humus, when by re" 
 pea'ed over-doses of any one element, or by the total neglect of others, 
 or by allowing certain noxious elements to accumulate, we depress the 
 productive energies of the soil. 
 
 An argument is frequently raised in disparagement of mould, that an 
 excess of vegetable matter, as in swamps or heath-moors, is unfavor- 
 able to a wholesome vegetation : on the other hand, experiments have 
 proved that certain plants will thrive in pure charcoal — plants which do 
 not deserve to be styled useful except by indirection^ transplanted from 
 rich garden earth, containing abundant resources in their systems, sup- 
 plied freely with M^ater perhaps saturated with organic matter, in a 
 close atmosphere charged with concentrated nutriment, in a green-house 
 which collec'^s the rays of the sun with great effect upon growth ; plants 
 such as these, many of which cannot survive a sudden change of tem^ 
 perature, and die out or are forgotten in a few generations, are brought 
 in comparison wi'h field crops, t e support of man and his fortunes! 
 It may not he, inappropriate, by way of comparison, to direct my readers 
 to those conditions of society in which a pampered aristocracy is found 
 in juxta-posiiion with a degraded, ignorant, and vicious populace : the 
 former-are the hot-house plants, the latter those noisome weeds which 
 from their very ranknesS are cumbersome to the ground. Happy is 
 that country in w'lich neither class exists, but a population of intelligent 
 freemen, with such qualifications of mind and body as ennoblethe race. 
 
 As tar as plants administer to the food of men and domestic animals, 
 their importance may be graduated by the amount of their fecula, gum, 
 oils, &c., or of albumen, &c. In order to obtain these products tl<e plants 
 are generally destroyed, some of them in embryo as seeds and tubers, 
 some more advanced in life : but we never wait until these latter sponta- 
 neously cease to live, because at the period of their natural dissolution 
 the r hyd -o-carbonaceous deposites have been converted into lignin. The 
 pro'einized deposi'es in the cells and nitrogenous solutions in the sap 
 have also disappeared ; they have done their appropriate duty, which 
 par'ly corresponds with that performed by the adipose deposites in the 
 cellular substance of animals, or by the fatty matters of bile. Vegeta- 
 bles, with a view to their self-preservation, are known to use the hydro- 
 carbonaceous substances in their sap for building up their structures, at the 
 same time borrowing, as I conceive, the necessary forces from the azotic 
 ingredients, un il the germs divert the juices measurably from the stem 
 and branches. In consideration of the collateral uses oi'azotized matter in 
 vegetables we are too apt to regard it as forming an integral portion 
 of a plant per se. The vegetable and vegeto-mineral kingdoms economize 
 nitrogen, not for its own sake, but for the advantageous reactions which 
 it promotes: the vege o-animal and animal kingdoms appropriate hydro- 
 carburets chiefly for that purpose. The same principle-may be extended 
 to their modes of growth at the incipient stage of their existence ; phane- 
 rogamous flowei'ing plants not being fecundated until the pollen reaches 
 the blossom, nor the animal ovum until the semen masculinum quickens it. 
 
The very compound ammonia which under favorable circumstances, such 
 as an abundance of carbonaceous aliment, might forward the growth of 
 plants, under other circumstances becomes the means of disintegrating 
 their frame- work even unto utter debility and death. It is for this reason I 
 deprecate an excessive use of, or an entire dependence upon, the fertilizing 
 salts now so prevalent, which will probably cause a more rapid ex- 
 haustion of the soil unless we keep oar farm§ in good heart ; and then 
 we may lay on the minerals with a liberal hand. Thus are true econ- 
 omy and high tillage combined. Our interest demands that we foster the 
 carbonaceous elements of the soil on the Atlantic slope of this conti- 
 nent, in order to compete with the middle States of the West, notwith- 
 standing the diseases of new countries which affect both animals and 
 vegetables: nearly all of them will soon be avoided by scientific and 
 careful husbandry, more particularly by draining. The refuse of our 
 homesteads and green manures must be our chief resource, and in pro-' 
 portion as we gain carbon by any available means, we should encourage 
 its still further accumulation by an equivalent admixture of mineral 
 bases, among which ammonia is pre-eminently serviceable, both as a 
 solvent or vehicle, and as a stimulant in the manner suggested. 
 
 In reply to those who consider the atmosphere competent to supply a 
 full amount of carbon both to the leaves and roots of our field and gar- 
 den crops, and who, conformably with this doctrine, rely upon mineral 
 manures, I would ask why the ammonia which is furnished in the same 
 way does not suffice. Can the vapor of water dissolved in air, or even the 
 dew which is deposited at night, sustain under ordinary circumstances 
 the welfare of the higher class of vegetables for a season, not to mention 
 a series of years ? It might as well be contended that no rain is needed 
 anywhere, because in Egypt the periodical overflow of the Nile ren- 
 ders it unnecessary there by soaking the adjacent plains to an extra- 
 ordinary depth, as that wheat can be raised on poor soil for many 
 successive years without the slightest artificial or natural additions of 
 carbon in some of its solid or liquid forms. 
 
 We do not propose adding compounds of nitrogen to worn-out soil 
 solely for the purpose of raising vegetable mould, although the 
 improvement in the soil is the first step in the improvement of 
 our vegetables, and consequently of our animals. Whether our in- 
 crease of wealth consist of azotized food which has been acquired at 
 the expense of hydro-carbonaceous matter in vegetables, or whether it 
 consists of hydro-carbonaceous organizable matter in the soil which has 
 been acquired at the expense of ammoniacal ingredients, the chemical 
 process is identical ; and when the value of good mould is taken into 
 account, the diflerence betw^een the market prices of the organized and 
 semi-organized products is not always in favor of the first. 
 
 During the decomposition of a manure heap or a compost bed, as long 
 as ammoniacal fumes escape, provided the air be allowed to percolate the 
 mass, and there be no deficiency of fixed alkalies and alkaline earths, I 
 fully believe that a positive addition of semi-organized substances results; 
 although the retention of ammonia is doubly desirable far direct ap- 
 propriation by growing plants, a desideratum, which may be in some 
 measure effected bv artificial means. Were, however, the loss of am- 
 
10 
 
 monia complete, which it generally is not, the porous character of the 
 new-born mould would attract back again a certain proportion. Thus 
 it happens that as in the atmosphere, carbonic acid, ammonia, and vapor, 
 hold a proportionate relation to each other, so do they in the soil near 
 the surface of the ground, and it is in consequence of the natural ina- 
 bility of the mineral bases to regulate their oMm movements satisfacto- 
 rily in reference to vegetation, that man is called upon to remedy any 
 defects or excesses. It is usually asserted by those who admit the 
 sapply of carbonic acid and ammonia to the roots from decaying organ- 
 ic matter, that the atmosphere was the primeval source of those elements; 
 they therefore refer the origin of vegetables or vegetable growth to that 
 A^ast magazine, as amply empowered to sustain what it originated. We 
 admit the joint influence of gases, liquids, and solids on living bodies, and 
 this we hold to be suflicient to account for all the material phenomena 
 and reactions of life. 
 
 Whether this theory be right or wrong, no injury can accrue from the 
 adoption of a practice founded on its requirements. We should by no 
 means place our sole reliance upon the natural but slow formations of 
 soil as food for our cultivated crops, any more than we should rely upon 
 the organic elements of the atmosphere, or of the same elements absorb- 
 ed by ground kept in fine tilih. For precisely similar reasons we should 
 object to feeding our domestic animals upon food slightly azotized, if our 
 aim be to gain flesh and nerve. Under favorable conditions then, and 
 by the aid of light, the pulverized surface of worn-out soil becomes slow- 
 ly self-renovated, provided its texture be porous and yet sufficiently re- 
 tentive; and this recuperation proceeds the more rapidly in proportion 
 to the amount of semi-organized substances already existing. A nucleus 
 assists, without being necessary to, formative action. We may not at 
 first, or at once, attain a pabulum adapted to sweet vegetation ; indeed 
 Ave might never succ'eed without slight extraneous additions. I therefore 
 do not recommend any purely natural sj^stem of agriculture for civi- 
 lized communities; but as a question of physiolog}^ I contend, that 
 as a coarse vegetation precedes the development of nobler plants, 
 so the commonest earthy bases, in conjunction with water and the 
 elements of the atmosphere, serve to prepare poor land for future 
 usefulness, by a succession of higher and higher subterranean products; 
 and among the elements of air I include phosphorus, sulphur, and some 
 other minerals, either in solution or mechanically suspended. 
 
 It is, moreover, questionable, whether the organfic acids in combination 
 with mineral bases, or oth er still more abundant ga^emcKS^Bibefca^s^i^aai con- 
 stituents proper of soil, are so unstable as generally supposed ; a doubt 
 which may be extended to the constituents proper of living vegetables and 
 animals, as long as easily-decomposable matters^in the circulation or other- 
 wise favorably located, are available for functional purposes; whether, 
 for instance, the exposure of those hydrocarburets to the atmosphere, by 
 repeated fallows, necessarily entails their speedy loss in the absence or 
 comparative paucity of growing plants ; the latter alternative, of course, 
 resulting in no necessary loss, provided the plants be allowed to rot on 
 the ground or within the furrow. My own impression is, that under the 
 circumstances stated, and as long as mdisture is maintained, partial de- 
 
11 
 
 ^f^d-jfr^''**^ .ai^M^6.«>.*<lf ^jr^-^i^OK. ^e*.,.^^^--^^ 
 
 composition is adequately compensated by ^ao^^Kaiaj^segteaiJZ^J^^EQi^^ 
 ^wne, these again to be supplanted in natural order by original hydrocar- 
 bonaceous deposites at the expense of the atm,osphere. Uncropped land 
 which has been kept constantly worked for several successive seasons, 
 or which has been lying waste for five or ten years, may be gradually 
 accumulating vegeto-mineral products peculiar to the climate, to such 
 an extent that the application of a little guano alone will ensure a re- 
 munerating crop of grain. This is no argument in disproof of my main 
 position, for I have uniformly discovered that, where the ground was de- 
 cidedly worthless and bare, the whole class of mineral manures disap- 
 pointed me ; but where a scanty allowance of humus gave them a chance 
 of turning that pittance to immediate account, the crop spoke for itself, 
 if the season was favorable ; although, as I have before remarked, it 
 was tasking the ground to its utmost strength for the purpose of giving . 
 the crop a good start. 
 
 The constitutional depravity of the middle regions in Maryland and 
 Virginia must be assigned to the exhaustion of available alkalies 
 and alkaline earths, and to the too rapid withdrawal of sulphur and 
 phosphorus. Let the proper mineral bases bear the right proportion in 
 a raw surface composed of rock lately disintegrated, and if the climate 
 be genial, there can be little doubt of a soil-formation, and subsequent 
 vegetation based upon it, even on a solitary island in the midst of the 
 Atlantic ocean. 
 
 The conclusion to which we arrive is, that animals, vegetables, and 
 the soil hold certain properties in common, alike affecting their growth 
 and the means of obtaining nutriment. When circumstances admit, 
 they all appropriate materials but little if at all removed in composition 
 from their own substance ; but they also are enabled to generate within 
 their system more or less compounds suitable to their immediate wants 
 from the same elements in simpler states of combination. The more 
 capital, therefore, we judiei^iiy invest in organic manures, or in mineral 
 manures with a view of fostering humus, the more deeply w« plough 
 and pulverize the soil within prudential limits, the larger interest accrues, 
 not only by the increased weight and quality of produce above ground, 
 but also below the surface. 
 
 Mount Hermon, Washington County, March, 1850. 
 
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