Soil

SOIL. Soil is distinguished from earth in that it contains a greater quantity of organic vegetable matter than the sands, gravels and clays, which constitute so large a portion of the upper surface of the earth's crust. The earths originally were composed of the detritus or decom position of the various rocks. Until this wear ing away and decomposition became partial at least no vegetation could subsist. This is pri marily brought about by the action of the oxygen of the air, by the action of rain, running water, floods, but more generally by the grinding power of glacial action which at some time seems to have been present on nearly every portion of the earth's surface. Upon the relations of Geology to Agriculture—Hon. James Shaw, in an address to the Northern Illinois Horticultural Society, truly said: Soils are derived from the decomposi tion of the rocks. The silent processes of nature, to-day, as in past geologic ages, are grinding rocks into soils, and re-cementing and hardening soils into stratified rocks. There was a time when the earth was, indeed, rock-ribbed; but atmos pheric and chemical agencies and aqueous forces kept in constant action, processes of slow decay, and the soils were gradually formed as precipi tates and sediments in ancient geologic seas. We all know the old proverbs about the constant dropping that wears away the stone, and the file of time that wears and makes no noise; but few realize how important a part these peaceful agen cies have taken in the creation of the present order of things. The frost and the rain, and other like agencies and energies of nature, are all powerful to bring about the mightiest results. If undisturbed by mechanical forces, the superficial clays, foams, sands, subsoils and soils covering the underlying rocks would be nothing but the residuum left after the removal by the percola tion of the water of the more soluble portions of the rocky ledges, which had decayed. The soil would be in situ. It would bear a close resem blance to the rocks from which derived. The geologist, by an examination of the rocks, could tell the nature of the soil with which they were covered, and,. by an examination of the soils, could designate what rocks they concealed. Pri marily, all soils are derived from fire rocks; sec ondarily, many of them are derived from water rocks. The• first resemble, in composition, the primary rocks; the second, having first been granites, then, by the decay of the granites and the transportation of water, becoming stratified rocks, whose decay and chemical combinations and separations, separated and assorted by the elements, oftentimes do not resemble the first at all. The general proposition is, however, true, that rocks differ from each other, and soils also resemble the rocks from which they are derived. In small patches, and to a limited extent, this . is true of the soils of the West. The alluvial bottoms of our rivers are generally, sedi mentary Tile, sometimes hungry sandy soils, but often black, fat, sedimentary deposits. The latter produces great crops of Indian corn, when dry enough to cultivate; but, when low and wet, it grows heavy crops of the coarse prairie and slough grasses. But the most marked illustra tion of the proposition under discussion, may be noticed in localities underlaid by the Cincinnati shales. Here the soil and subsoil, if undisturbed, is a close grained, finely comminuted, buff or straw-colored clay. It is so compact and tenacious that it becomes water-soaked, and has not the power to rapidly absorb surplus moisture. The best soil is the formation known as Loess, by western geologists. It caps, and in most cases, makes up a large proportion of the bluff ranges along the Missisippi river, and some of the inter nal streams in that part of Illinois; it sometimes extends back for some miles from the bluffs into the interior; but, in the latter case, it is seldom pure, but is mixed with other sands and clays. It is white, buff-colored silt, of extreme fineness of texture, where purely developed; but it often consists of marshy, sandy deposits, and various mixtures and clayey combinations—for vines and deep-rooted trees no better deposits exist in the State. It owes its origin to the silt washed up by broad sea-like lakes and wide lake-like rivers. It affords little resistance to the penetrating root lets of trees, is well-drained, and is unsurpassed, Other for wheat, fruits, grapes or vegetables. The foregoing remarks are based on the argu ment that soils are derived from the decay of the underlying rocks. An examination of the soils of the prairie.region of the West, however, will soon convince any one that this statement, as a matter of fact, is true to only a limited extent; it will do for fragmentary patches and driftless regions. Over wide stretches of country the decay of the rocks has not formed the soils them. Transportation of soils, a uni versal mingling of materials derived from widely -different sources, is a fact susceptible of easy demonstration. That tremendous force which tore the bowlders from their parent outcrops in the distant Lake Superior regions, and drifted them along on their southward journey, which grooved and planed the surface of the solid rocks, which strewed, for hundreds of miles, beds of clay and sand and gravel, whether floes and bergs of ice, borne by winds and currents loaded with stones and detrital matter, or strong water currents mingling and wearing the moving beds of abraded materials, or the procession of the slow, silent, all-powerful glaciers, grinding the solid stones into soils, as wheat is ground to flour between the upper and nether mill-stones, whe ther one, or all these causes combined, it mingled. mixed, transported and formed the soils to such an extent as to well nigh destroy their separate and characteristictic origin, and greatly increase the difficulty of their proper classification. In attempting to classify soils and earths thus made and mingled there is no end to the distinctions and divisions. Soils are light or heavy, warm or cold, dry or wet, compact or porous, fine or coarse, hungry, leachy, loamy, sour, sweet, clayey, sandy, limy, marly, and various combin ations of these too numerous to mention. Silica, or the earth of flints; alumina, lime, magnesia, potash, and various salts and metalloid com pounds unite in various combinations to make up these soils. The humus, which gives rich ness and blackness of color, is chiefly derived from successive growths and decays of grasses and other vegetations. The question as to what soils will produce and mature good and constant crops depends not only upon the nature of the soils themselves, but also upon climatic influ ences, and upon the nature and properties of subsoils. If the subsoil is gravelly, marly, por ous, leachy, sandy, or of such a texture as not to retain water too easily, almost any soil will pro duce trees and fruits. But, if a hardpan, or other tough, impervious clay, happens to be the subsoil, so as to retain the surplus moisture, the best soil in the world unless a very deep one, will not respond to a liberal cultivation, with a generous supply of good, vigorous, healthy, and sure crops. The best soils for wheat are dry,

firm, -but easily disintegrable, and rather com pact soils, such as contain a good proportion of lime and clay. The best Indian corn is raised upon the deep humus, prairie soils and river bot toms of the West, but a good wheat soil is also a good corn soil if the summer is long enough to ripen the crop. In this connection the classifica tion of soils, their composition and their organic and inorganic matter will give a good idea of what constitutes soils for cereal crops. A loess soil, as heretofore stated, is admirable for the grains, grasses, and for fruit. The classification of Boussingault is excellent and is as follows: Specific gravity is also one of the tests of a good soil, since it will show if the soil be finely comminuted the presence of a good proportion of clay. The percentage of clay and sand in various soils from pure clay (pipe clay), to humus soils and peaty soils is as follows: Pure clay, pipe clay, sixty per cent. silica, forty per cent. alumina, oxide of iron chemically combined. Strongest clay soil, brick clay, pure clay with five to ten per cent. of sand which can be separated. Clay loam fifteen to thirty per cent. fine sand and pure clay. Loamy clay thirty to sixty per cent. sand and pure clay. Sandy loam sixty to ninety per cent. sand and pure clay. Sandy soil containing no more than ten per cent. of pure clay. Manly soils, in which the proportion of lime is more than five, but does not exceed twenty per cent. of the whole weight of the dry soil. Calcareous soils, in which the lime exceeding twenty per cent. becomes the distinguishing constituent. Vegetable soils from garden mold, which con tains from five to ten per cent., to the peaty soil in which the organic matter may amount to sixty or seventy per cent. These soils again may be clayey, loamy, or sandy, according to the pre dominant character of the earthy admixtures, A fertile soil, therefore„ consists of three earths, clay, sand, and lime mechanically combined, organic matter from the decay of plants, etc., which may be resolved into carbon, oxygen, hydrogen and nitrogen, and the inorganic ele ments, in combination, chemically, with metals, hydrogen, oxygen, chlorine, and sulphur. These are in small quantities. Thus chlorine produces the chlorides, iodine, the iodides, sulphur, the sulphurets, and sulphuric acid; phosphorus, the phosphoric acid; potassium, the potash; sodium, the soda and common salt; calcium, the lime; aluminum, the clay; silicon, the sand; and iron and manganese, oxides and sulphurets. The mechanical texture of the soil has a strong influ ence upon itt practical fertility, very heavy clay, and very light sands, being both, for opposite reasons, apt to produce badly. The soil in which the particles are the finest, so that the air can enter, and the roots spread without difficulty, is, other things being equal, the best. In clay soils this division of the particles must be pro duced by the plow and other mechanical means; while in loose sands it is too great, and must be amended by an admixture of clay and other sub stances. The cause of the great and lasting fertility of prairie soils, is, first, its extreme com minution—fineness—and its large proportion of clay, sand, and organic and inorganic elements. The color of the soil is not always an indication of its fertility. As a rule, however, dark soils are the most fertile. The absorbing power of soils is another indication of fertility, since a porous, or other soil that will easily absorb water and hold its vapor, is generally a fertile soil. The following table from Schubler, shows the rela tive absorbing power of the soils named: Thus while sandy lands may suffer from long continuance of dry weather, a neighboring field abounding in humus may absorb sufficient mois ture from the air to serve all the requirements of vegetation. The power of saturation by water, and the retention of moisture, vary in the same manner, and nearly in the same degrees. Au other important property of soils is their power to absorb oxygen from the air. According to Schubler: Soils lose, in drying, the property of absorbing oxygen from the air, but regain it in the same proportion as before, on being moistened. The action of organic manures, and the production of carbonic acid, depend on the existence of oxygen in the soil. Capillary attraction or power, means the power by which a liquid ascends in the interior of a capillary tube, or tube of small bore, above the surface of the liquid which sur rounds it. The phenomenon occurs in solid bodies which are capable of being wetted. Thus, when water is poured into the basin of a flower pot, the soil gradually sucks it in, and becomes moist even to the surface. The same lakes place in the soil in the open fields. The water from beneath—that contained in the subsoil—is gradually sucked up to the surface. Where water is present in excess, this capillary action keeps the soil always moist and cold. Evapora tion takes place from the surface of the land, and as each atom of moisture is taken up into the atmosphere, its place is supplied by another atom, communicated by the contact of the particles of soil, the more superficial acting on the deeper particles like so many pumps, to elevate the water, and supply the loss. Thus a naturally porous soil may be kept injuriously wet by an impervious subsoil several feet below. Drainage counteracts this. The capillary action of the soil, however, is an important action of the soil, since thus the vapor of water is con stantly passed upwards from below, to supply that lost by evaporation at the surface during droughts. A moderately compact, and yet por ous soil, has strong capillary power; and hence, again, another reason for its fertility, since a soil, when abundantly dry, is always unpro ductive; and for one principal reason, that it is only in a soluble form, that is in combination with water, that the elements of plant food can become available. Thus, given a virgin and fer tile soil, capable of producing those crops nat ural to a climate, it would seem to be of the utmost importance that the farmer keep it up to the original standard. This is accomplished by fallowing, manuring, or by a proper succession of crops, or, better, by a combination of the three. (See articles Fallow, Manure, and Rota tion.) There is another agent fully as impor tant, and that is disintegration. This enables natural agents to act promptly in restoring lost fertility, both summer and winter. These are heat, electricity, moisture, carbonic and other acids formed in the soil, and the complex chem ical changes constantly going on in a soil in which heat, moisture, and porosity are present in normal conditions. This being the case and the elements of fertility present in due propor tion we have a fertile soil.