§ 4. The importance of established principles as they are considered in the present state of agricultural knowledge, induces us then to state somewhat in detail their practical bearing.

Facts differ from principles. The latter are deductions from the former. It is often the case that what are regarded as facts are imperfect observations. Principles which may be deduced from supposed facts may be, and often are, wrong. When practice is based upon observation, it is quite necessary we should not be mistaken in our facts. We may cite one or two examples of a mistaken theory based upon imperfect observation and an ignorance of the functions which the vegetable kingdom performs. Thus the idea of an injurious acid in the soil is the basis of the application of marl and lime to correct that condition, and the inference is, that the beneficial effects of marling is due solely to the correction of acidity. The acidity itself is founded upon the growth of sheep sorrel, pine and other plants, which impart the taste of sourness to the palate. Sheep sorrel, however, grows upon poor soil—not upon an acid soil, for it often grows around lime kilns, where it is impossible that an acid should exist at all. We have seen it growing with great vigor through a stratum of air-slacked lime two inches thick, where it had been thrown from a lime kiln. We have seen sheep sorrel also covering a dry hill-side which had become poor by cultivation; whereas, it is rare to see this plant growing in moist peaty grounds, where acids from vegetable decomposition are usually expected. The fact is, in all plants which impart to the palate an acid taste, we may be assured it is not due to an acid soil, but to the action of their own peculiar organization, and this acid will be found to exist under any condition in which the plant can be grown. The soil has really no agency in its production; for sow sorrel seed in white pure sand and water, with that which is free from acidity, and the sorrel will be acid; it is characteristic of the plant, and independent of the soil in which it grows. Yet marl is useful, though our notions of its action are erroneous; still the question is highly practical; it would govern our practice in the quantity to be used; for if it is merely wanted to correct acidity, a small quantity will suffice for that. Whereas, if it is maintained that it furnished directly or indirectly food to the crop, a much greater quantity will be required.

§ 6. Soils cannot be systematically classified. We may divide them so that, considered in the extreme, the strong lines of demarkation will appear quite distinct, as a clay soil and a sandy one, but these graduate into each other and the lines of demarkation disappear insensibly. So we find peaty soils, and in districts where chalk underlies the surface soil, we may distinguish a calcareous soil, but both kinds lose their characteristics by intermixtures of clay and sand. We may however, say with truth, of any particular locality, that it has an argilaceous, calcareous or sandy soil as the case may be. Such a statement should be made, but this does not amount to a classification. We shall not, therefore, attempt the arrangement of soils into a systematic classification; it will be sufficient to indicate in our nomenclature the predominant element, whether it is clay, sand, lime or vegetable matter. It is not, however, proper to omit the statement that sand or silex is the basis of all soils except those in which organic matter greatly preponderates, for, in clay soils silex still exceeds in quantity the clay, but still clay masks the silex, though it is less than one-half, and hence has to be treated as an argilaceous soil.

But the real nature of soil is not fully stated, by any means when they are merely referred generally to the preponderating element, there is left out of view certain elements which, so far as fertility is concerned, are quite as important, though they exist only in minute proportions. We shall, however, take the ground that all the elements of a soil are important, and take away entirely any one of them and its fertility will be affected for certain crops at least, if not for all.

§ 7. The soil elements are only few, when compared with the number of known simple bodies; thus, while the known elements amount to about sixty-two or three, only about thirteen or fourteen play any considerable part for the benefit of the vegetable kingdom. The latter are embraced in the following list, viz: Oxygen, hydrogen, nitrogen, sulphur, carbon, phosphorus, the base of silex, or silicon potash, soda, lime, magnesia, clay or alumine, iron and manganese. Iodine and chorine also exist in plants and soils. Potash, soda, lime, magnesia are compounds of oxygen and a metal, whose names terminate in um—as potassium, sodium, calcium, &c. The first seven which stand in the list, are unmetalic bodies, the last seven are metals. Oxygen, hydrogen and nitrogen in their free or uncombined states, are aeriform bodies; the others are solids possessing different weights. The foregoing bodies or elements exist in the rocks which compose the earth's crust, not however as simple bodies, but in combination with each other, forming what are usually known as simple minerals. Thus, quartz, mica, felspar, hornblende, talc, serpentine, carbonate of lime consist of these elements, and furnish them when they decompose or disintegrate into soil. The foregoing minerals constitute the great mass of the earth's crust. To take an example of the number of elements which a simple mineral as hornblende furnishes may be seen by the results of analysis. Thus hornblende, felspar and serpentine are composed of

HORNBLENDE. FELSPAR. SERPENTINE. Silex, 45.69 66.75 43.07 Alumine, 12.18 17.50 0.25 Lime, 13.83 1.25 0.50 Potash and Soda, ..... 12.00 12.75 Magnesia, 18.79 ..... 40.37 Oxide of Iron and Manganese, 7.32 0.75 1.11

A simple or homogeneous substance, therefore, furnishes many soil elements, and as rocks, such as granite, gneiss, mica slate, hornblende, are made up of several minerals in mixture, or are aggregates, we may see how a single rock furnishes all the essential elements of nutrition.

The rocks which are composed usually of simple minerals, yield one or two elements in excess: silex and alumine, and hence these necessarily predominate in most soils. Almost all of these minerals furnish other bodies in minute doses, potash, and soda, together with combinations of lime and silex, potash and soda with phosphoric acid. The latter forms such small proportions that they were at one time set down as accidental and unessential soil elements, but now they are known to be all-important.

§ 8. The mechanical condition and weight of any soil depends upon the existence of the predominating element. Sandy soils have a loose porous texture while an argilaceous one has a close one, and may be impervious to water.

The weight of soils is dependent of course upon composition:

A cubic foot of dry silicious soil weighs,* 111.3 pounds, A sandy clay, 97.8 Calcareous sand, 113.6 Loamy clay, 88.5 Stiff clay, 80.3 Slaty marl, 112. A soil richly charged with vegetable mould, 68.7 Common arable soil, 84.5

The average weight is about 94.58, and when charged with water will weigh 126.6 pounds.

§ 9. Soils which are formed from the debris of rocks, contain a large though variable proportion of sand and silex. Of one hundred and forty-six soils of Massachusetts, the average quantity of silex is 71.733. This is insoluble matter. The soluble and that which is fitted ultimately to enter into the composition of vegetables is about 15 per cent., of which 2.075 is a salt of lime. The midland counties of N. Carolina furnish coincident results. But the eastern counties, which have extensive tracts of swamp lands, differ considerably from the foregoing. The silex and alumine in many large tracts, amounts to less than 50 per cent., and sometimes is even less than five, on indeed must be classed as a peat unsuitable to cultivation.

Of lime, which is so much talked about, and is truly an essential element in soil, it appears from hundreds of analyses, that it rarely exists in large proportions. Such is the case in the soils of New York, even where they overlie a limestone, its average quantity rarely exceeds one per cent., and in large tracts it scarcely comes up to one-half of one per cent. In the western States there is about 1.50 per cent. In 48 European soils, noticed by Dana, it is 1.860. European soils agree generally with American; all things, therefore, being equal, their treatment with fertilizers will be based upon similar rules. We must not, however, disregard the influence of climate and temperature. These are important elements in agriculture, but so far as the composition of the soils of all the great geographical divisions are concerned, their differences have arisen from cultivation mainly; in their natural state they were much alike.

§ 10. Soils are analyzed for the purpose of determining their constituents. Under long cultivation some of the important elements are so much diminished that fertility cannot be claimed for them. We shall show hereafter how soils become infertile, and what becomes of the fertilizing matter. The proof that soils actually part with certain elements essential to fertility has been fully ascertained and determined. This result is certainly due to chemistry, and it is a great result; for, for a long time the contrary was maintained, and even now many believe that by a rotation of crops and good manipulation, soils may be maintained for an indefinite period in a state of productiveness. So, also, it has been believed, and is still in cerquarters, that lands thrown out to commons, or to remain a few years fallow, will recover their original fertility. The sooner, however, such opinions are abandoned the better, as they lead to an erroneous system of agriculture.

A destructive practice really grew out of the doctrine, it was the continued use of the axe and fire, followed by long fallows when exhaustion was nearly completed. It demanded extensive plantations, and had such a system of extermination of timber been followed in a more northerly clime, the loss of wood and timber would have become a severe calamity.

§ 11. I have observed that temperature independent of the composition of soil is an essential element in agricultural practice. It often determines the kind of crop as well as the season when it is to be planted. In England maize finds an incompatible climate, and hence, as a substitute for grain wherewith to fatten cattle, root crops as the turnip is resorted to. Maize germinates in a soil when its temperature is as low as 60°, and also when it rises to 105. Germination is however arrested when the temperature reaches 116-120. In tropical regions the order of things is somewhat changed. So much heat exists in the period answering to our summer that wheat, barley and oats are sown in the coolest months. So in mountainous regions, temperature becomes the controlling element. In the latitude of the Swiss Alps in Europe, wheat ceases to germinate at 3400 feet which corresponds to the latitude of 64°.

Oats, at 3500, corresponding to latitude, 64° Rye, at 4600, corresponding to latitude, 67° Barley, 4800, corresponding to latitude, 70°

In Northern New York at the hight of 2000 feet above the ocean, wheat is an uncertain crop, or is liable to be cut off by an early frost; while oats, barley and rye come to maturity. So far as these facts go, it appears that the solid masses of the globe as the rocks, have little influence upon crops; but at the same time cultivation never fails to produce its influence, that of impoverishing the soil.

I have shown in a former report that the soils of the Southern States are not only formed from the rocks of the country, but that they remain upon the place where they are formed or in situ. The proof may be found in every railroad cutting from Virginia to Alabama. Wherever a quartz vein penetrated the rock it remains unchanged in position, it presents the interesting and curious phenomenon of an irregular band which seems now to have been forced through yielding and soft materials. Quartz veins standing up for 20 feet unsupported except by soft yielding materials. It is rare to see any thing of the kind in New York or New England. There, at some former period such soft materials with their veins of quartz were swept off by a mighty flood of waters. This erosion no doubt extended deeply or down to the solid plane of rock. No flood however, has disturbed the debris of rocks in North-Carolina, and hence it is no doubt true that this debris is really one of the most ancient products of the globe, equaling in age the Silurian or Devonian systems; still there is no clue by which its age can be exactly determined, it is now a soil often 25 to 50 feet deep. This condition of the soil no doubt has some important influence upon its agricultural capabilities. The plough in many places must continue to bring up for years an unexhausted soil where the mass is penetrable. This new soil turned up by deep ploughing, however, is necessarily coarse, especially where it is derived from the coarse schists, as gneiss and mica slate, hence it requires before it is really prepared to receive a crop to be exposed to the chemical influence of the air and the action of frosts whose effects are mainly to increase its fineness.

§ 12. Simple bodies enumerated in a foregoing paragraph seem to require a fuller notice, particularly as to their properties or functions as soil elements. When either of them is isolated they appear to be neutral bodies; that is, they manifest but little disposition to form combinations. Nitrogen and hydrogen would remain in contact with each other for ages without entering into combination. Oxygen and hydrogen never combine when confined together in a vessel. A force is necessary to effect it in either case. A flame however, unites them suddenly, attended with a violent explosion. When burnt in streams issuing from small orifices, they combine evolving great heat and intense light. The product of combination is water, and nothing else. Most bodies have a strong affinity for oxygen; and hence, it is an element common to most solids. The air or atmosphere is composed of oxygen and nitrogen, water, of oxygen and hydrogen, iron rust of iron and oxygen; potash, of oxygen and potassium; soda, of oxygen and sodium; lime, of oxygen and calcium. The general term for compounds of the metals with oxygen is, *oxide,

* The word oxide, properly terminates in ide and not yde, because in framing the nomenclature, this termination was fixed upon; according to idiom it would be spelt oxyde.

§ 13. HYDROGEN, is the lightest body known, and is always aeiform except when in combination. It has neither taste or smell, and is never found in nature uncombined with other bodies. Although it exists in many bodies as oils, and those which are termed organic, yet water is the body in which it most abounds—not that its proportion is greatest in water, but the general diffusion of water over the globe and in most bodies, makes it the great source of this element.

§ 14. NITROGEN, is another aeriform body, neutral and of little power; it would seem almost destitute of affinty, for other bodies, if we judge of its perperties as it exists in the atmosphere. Indeed, though it has feeble affiinities, it is for that reason, an element of one of the most powerfully corrosive bodies known. Nitric acid for example is only oxygen and nitrogen, but who ventures to taste it the second time, notwithstanding we inhale the elements of nitric acid at every breath. What substance is more singular than ammonia, or harthorn, which is only nitrogen and hydrogen chemically combined. It will be seen in the sequel that nitrogen performs important functions in the soil.

§ 15. CARBON, is a solid. We feel relieved when a solid presents itself, something to be seen and handled. It is pure in the diamond; nearly so in anthracite coal, and in the purest charcoal. It has only a feeble disposition to combine with other bodies. Heat materially puts its particles in a combining state. It forms with oxygen, carbonic acid, an aeriform body sufficiently heavy to be poured from a tumbler. If poured upon flame it extinguishes it, showing that though one of its elements is a combustible and the other a supporter of it, that it is itself an extinguisher when applied to burning bodies, and hence has been and may be used to extinguish fires—when inhaled, it acts as poison to the system; and yet in all organic bodies it is a basis of support.

§ 17. The four preceding elements are often called by way of distinction, the organic elements of bodies; because all bodies which are organized are composed mainly of them. The following examples will show more clearly than any other statement, the fact alluded to. For example, hay, in 1,000 pounds, is composed of:

LBS. Carbon, 458 Hydrogen, 50 Oxygen, 337 Nitrogen, 15

§ 24. The organic part of a soil consist apparently of carbonaceous matter, and taken as a whole, it is the brown or blackish part, and which is consumed when ignited. Its appearance, indeed, is due to a species of combustion which is carried just far enough to char the vegetable matter. In warm climates it is nearly all consumed, while in cold it constantly accumulates, and forms at the surface a coat of blackish mould. The term organic applies to this part of the soil. On the mountains of this State it is often more than a foot thick. In the swamps of the eastern counties it is often ten feet thick, while in the midland counties it is only sufficient to give a brown stain to the surface. It does not seem to accumulate in consequence of a slow combustion, or as it may be termed decay which takes place.

In common language, the organic part is known under a variety of names, as humus, mould, vegetable mould. It is, however, a complex substance, and is constantly undergoing changes which promote vegetation. Chemists have obtained several distinct substances from it. It is really a mixture of organic and inorganic bodies. A portion of the organic matter is free, that is, it is uncombined with the inorganic part. Other parts are in combination with lime, magnesia, iron, potash, soda, &c. The latter are soluble, and also fertilizing matters, and play an important part in vegetation. The cause of this intermixture of organic and inorganic matter is to be traced to its origin. Thus, organic matter being the debris of the vegetables which had grown upon the soil, it must necessarily contain also the inorganic part which belonged to the living vegetables. From this fact it may be inferred that this matter is, in the proper proportions, to be employed by any subsequent crop.

§ 25. VEGETABLE MATTER after death passes through a series of chemical changes, which gives origin to the numerous compounds found in organic matter. These changes are due mainly to the absorption of oxygen. The first substance formed from woody fibre after the death of the plant, is ulmic acid. Another portion of oxygen changes ulmic acid into humic acid; and the last is changed into geic acid; on a farther oxydation it passes into crenic acid; and finally by the same process into apocrenic acid. In an old soil, all these bodies exist simultaneously. The most important, or those which are immediately active, are the three last, geic acid, crenic and apocrenic acid. All the foregoing bodies are the products of the decay of plants, when exposed in the soil to air and moisture. They cannot be distinguished by sight, and the whole mass is simply a homogeneous brown substance. But it is richly charged with the elements of fertility.

We may omit the details respecting the chemical constitution of these bodies. It will be sufficient to state in this place, that they are feeble acids; and yet possess considerable affinity for inorganic matter, lime, magnesia, ammonia, potash, soda, iron, etc.; so much so as to combine and form with them salts, which are at once in the proper state to be received as nutriment into the tissue of growing vegetables. This organic matter, however, is remarkable for its affinity for ammonia; the result, therefore, is that this important substance may be detected in vegetable mould, though it may be chemically uncombined with the foregoing acids; it may be present as a mixture, yet being present, it will be disposed and ready to combine with the crenic and apocrenic acids, in both of which nitrogen may be always detected. Organic salts, formed by the union of organic acids, with lime, magnesia, potash, ammonia, etc, are the proper food for plants; and hence, it will be a maxim with the farmer to take such measures as the nature of those substances require to increase it upon all occasions which occur. The greater the amount of these salts in his soil, the greater his crops.

§ 26. From the foregoing statements we may deduce the following principle, that there is a mutual action of the organic and inorganic parts of the soil upon each other, and that to this action fertility is, in a great measure, due.

In order that these mutual actions may be better understood, we proceed farther and state, that those substances which are called silicates, have but a slight if any tendency to act upon each other. They are, however, gradually decomposed by carbonic acid, the effect of which is to form with the base of the silicate a carbonate. Thus in the case of granite and similar compounds, the felspar and mica which are silicates, are slowly decomposed, and the alkali, as potash, or alkaline earths, as lime and magnesia, or even iron and manganese of the rock, lose their silica, or are disengaged therefrom; and the carbonic acid combines with them. These being soluble compounds, are liable to be washed out and carried to the sea, while the insoluble silicate of alumina, or its pureform, remains behind. The consequence of this is, that the soil is relatively richer in clay than before, and the longer the chemical changes are going on, the larger the quantity of clay in the soil; and it is agreeable to experience that soils become stiffer by cultivation. By this process they become less adapted in the course of time to certain crops in consequence of this change of constitution. Large districts which once grew the peach luxuriantly, seem to have lost in part the power or ability, or, at any rate, the peach tree does not thrive so well in the oldest districts of New York and New England, as it did in the early period of their settlement. It is not possible probably to be satisfied fully with respect to the cause why the peach is cultivated with difficulty, but the fact that the soil by cultivation becomes more close and compact, may be remotely connected with the change we have stated. It has been attributed to a change of climate, but it is not true that the climate has changed, and hence we are disposed to refer the change in question to a change in the soil.

§ 27. In North-Carolina the natural supply of fertilizers exists in the marls of the lower counties, together with the organic matter of the swamps and bogs. The two exist often in juxtaposition. Experience has proved that marl applied to exhausted lands is often injurious. Now this exhaustion extends to the organic matter, though it also exists in its inorganic also. But experice further proves, that however large a quantity of the latter is applied, little benefit is secured so long as the first deficiency exists. We may see the reason why no organic salts can be formed in the absence of organic matter. The inorganic matter cannot find the proper elements with which to combine, and which the constitution of the vegetable requires. The practical inference is, that marls should be composted with organic matter, as leaves, straw, and weeds, which are free from seeds, or anything which has lived. Or, another plan may be pursued—supply the organic matter from a green crop, as a crop of peas, ploughed in. In certain parts of the State, clover or buck-wheat may be resorted to. The gain arising from the latter practice, arises from the ability of these crops to take from the atmosphere the organic elements, and deliver them to the soil, a process over which the planter or farmer has no control, except the institution of means. Under many circumstances, the organic matter may be supplied more cheaply by sowing seed than by composting.

The importance of organic matter in soils has been sustained by the experience of ages; but there was a time when this point was denied by the ablest Chemists of the age. It was maintained, that the ash or the inorganic part gave to the soil all that was important, and hence certain practices were recommended which were in accordance with this theory, such as burning manures, burning turf and the like. Happily, this question has been set at rest, and the best Chemists admit those views which the experience of ages has confirmed independently of chemistry.

§ 28. But the point which bears more immediately upon the principle respecting mutual actions, comes in play subsequently to the decomposition of the silicates; which, so far as inorganic matter is concerned, are inert; but the lime and alkalies once freed from their original combinations with silica, becomes fitted to act at once upon organic matter, and form with it salts. This decomposition may take place where no organic matter exists by the carbonic acid of the atmosphere, but it happens that organic compounds furnish also carbonic acid to the soil; for it is displaced when carbonate of lime or potash is acted upon by an organic salt. Crenic acid, acting upon carbonate of lime, sets free the carbonic acid, and this, in its turn, acts upon the silicates to decompose them, and thereby sets the alkalies and alkaline earth also free. There is then a double mutual action, as it were, constantly going on in the soil, by which nutriment is furnished to the crop. Some physiologists maintain that the presence of a living body, as the root of a growing plant, effects decomposition similar to the action of sulphuric acid in converting starch into sugar. However this may be we are inclined to believe that the root has power to act and effect changes upon the elements of soil which are unknown in the laboratory of the chemist; and many substances which are insoluble by chemical agencies, become soluble by the action of the roots of vegetables.

§ 29. The foregoing facts and principle do not change at all the action of the farmer; they go to sustain his practice in providing fertilizers by means of composts, formed by mixing the organic and inorganic bodies together, and for the purpose of giving them time and opportunity to effect those chemical changes, of which we have spoken. These never fail, while fertilizers in other states do. The foregoing are some of the chemical changes which take place in the soil, and which are mostly due to the presence of organic matter. All the facts go to prove the importance of organic matter, and the necessity, therefore, to supply it when from any cause it is wanting or deficient in quantity.

§ 30. In addition to the lime and other mineral bodies which the organic salts furnish to plants, it is plain that carbon is also one of the elements supplied. To make this plain we annex the composition of one or two of these organic bodies. Humate of ammonia consists of:

Carbon, 64.75 Hydrogen, 5.06 Oxygen, 26.22 Nitrogen, 3.97

Humate of ammonia, it will be perceived, contains more than half its weight of carbon, which may be taken up in the circulating sap.

Humic acid is composed of:

Carbon, 65.30 Hydrogen, 4.23 Oxygen, 26.82

It will follow, from the foregoing, that carbon, which forms the largest part of a vegetable, is not derived entirely from the atmosphere. The soil, through the medium of the roots of the plant, furnishes at least a part of this essential element. In certain plants, as wheat, rye and oats, it is very possible that all the carbon is derived from the soil; while in beans, clover, lucerne, etc., a large proportion may be derived from the atmosphere.

§ 31. The mechanical or physical conditions of soils differ according to their composition, and these physical differences must not be disregarded. It is well known that a clay soil contains under ordinary circumstances, more water than a mixture of clay and sand, and much more than sand alone. This fact may or may not become a serious injury to growing crops. It will depend upon the season. If it is very wet serious injury may be expected, or if it is very dry the crop will suffer, but not in the same way. All surfaces, whether composed of clay or sand, become dry by the evaporation of water, and the evaporation not only effects the surface but extends to a great depth; water seems to rise up to the surface from beneath to supply the waste. In confirmation of this view it is not uncommon to find a saline matter upon the surface in dry weather, which has been in solution in the water brought to the surface by this process. In many places in Wake county, N. C., the naked soil in ditches is covered with an incrustation of sulphates or iron and alumine, an astringent salt injurious to vegetation. This incrustion is formed only when there is a drouth; it is a gradual process. In countries where a whole season is dry, the soil becomes whitened with salts. Rains dissolve them and they sink again into the soil, though a portion will be carried away by water. An effect of a drouth upon a clay soil is to cause a shrinkage of the mass. It will then become still more difficult for roots to penetrate it, and hence, when drouth occurs early in the season, the crop is starved for want of nutriment, the roots cannot spread through an impervious mass. But sand simply dries without diminishing its bulk, but this process takes place with greater rapidity than upon clay soils, the latter being close and more retentive of moisture than the former.

§ 32. The rise of water to the surface from beneath, is familiarly illustrated by the putting of water into the saucer of a flower pot; its rise to the surface is well known. Flower pots are watered with common rain water or charged with fertilizing matter which is conveyed to the roots. In long continued drouths when the water rises from a depth of 4 or 5 feet, instead of carrying up matter compatible with the nature of the plant, the astringent salts take their place, injurious effects to vegetation take place in addition to those which arise directly from e want of rain. These injurious salts are easily corrected by the use of lime or marl. When they reach the neighborhood of the roots if lime is present, it will decompose the salts and form gypsum. Fruit trees which send their roots deeply into the soil are often injured by the presence of these salts. From the foregoing facts it is evident that the subsoil should be examined for poisonous salts, and when the ditches or deep layers are exposed in cuttings for roads, and should become partially incrusted with astringent salts, it will be important to institute means for correcting this condition of the deep subsoil.

§ 33. The foregoing remarks apply to those varieties which are purely clay or sand. Composition may modify results materially; if for example a soil whose composition retains a preponderance of clay and yet has a due admixture of organic matter and lime, its ability to stand a drouth is greatly increased—for organic matter and lime not only retain moisture strongly, but they affect the texture favorably, and counteract the tendency to excess in shrinkage.

§ 34. As drouths in North-Carolina are much more injurious than excess of rain, it becomes a question of importance to know how to guard against their effects. The first point to be attended to, is to drain deeply. This will affect gradually the texture of the clay; it will become more porous, while its natural affinity for water will not be diminished; that is, it will be sufficiently retentive while the excess of water will be drained off. Clay may be regarded as requiring a specific amount of water; but at the same time its capacity for receiving and holding a greater quantity than this, is proved by experience. Another change may be affected by the free use of organic matter, which, when mixed with the soil, makes it porous. In the cultivation of not only clay soils, but sandy ones, crops should be planted as early as possible, that the surface may be protected by the shade of the growing crop. To be able to plant early, in clay soils especially, the water must be disposed of by drainage. Two weeks may be saved in many cases by drainage; that is, the land will admit of the plough two weeks earlier in drained, than in undrained lands. Give a crop of corn two weeks more of growth than another piece equally well prepared, and the former will live through an ordinary drouth without injury, while the latter will not become half a crop.

§ 35. Absorption of moisture from the air takes place principally during the night, and unabsorbative power is less in sandy than clayey soils. This respite from heat, which causes so much evaporation during the day is of the highest importance. Even when dew does not fall, soils take a small quantity of water from the atmosphere. A stiff clay, it is said, sometimes absorbs one-thirtieth part of its own weight. Dry peat will also absorb nearly as much, but its power depends upon its condition; if very fine it absorbs more than clay; if coarse, less. The best condition of a soil is without doubt a mixture of clay and organic matter, where it is necessary to guard against droughts.

§ 36. The surface temperature of soils differ according to their composition. Water in all soils favors a low temperature because the evaporation carries off heat in the invisible vapor which rises from the surface. So long as an active evaporation goes on the surface continues cold, hence in swamps and bogs where the supply is inexhaustible, very slight changes only occur during the summer. When the surface becomes dry it begins to rise, and if the air is only 60° or 70° in the shade, the soil will absorb and accumulate heat and may rise to 90° or 100°.

Color has much effect upon temperature. The darker the color, all things being equal, the greater is the absorbative power. The correctness of the common opinion with respect to the natural coldness of light colored clay soils is correct.

§ 37. It is stated by good authority that the amount of evaporation from an acre of fresh ploughed land is equal to nine hundred and fifty pounds per hour for the first and second days after plowing. The rapid evaporation diminishes every day. Evaporation begins again by hoeing, but the moist surface thus exposed has other functions besides the evaporative one. Moist surfaces are much better absorbents of ammonia from the atmosphere than dry ones, and one of the most important effects of stirring the soil often, arises from its increase in absorbative power. Water in the soil is disposed of by forest leaves or by the vegetable kingdom. A single tree 8½ inches in diameter and 30 feet high expired from leaves in 12 hours 333,072 grains of water.

§ 38. An acre of woodland evaporates 31,000 pounds in 12 hours. During the summer, embracing 92 days, the whole amount of evaporation will amount to 2,852,000 pounds. Forests and vegetation generally largely aid the disposal of excessive water in the spring. Water of course accumulates in the soil during winter. Our wells receive their supply and springs have their sources of water replenished.

It is true, however, that the removal of forests presents a seeming anomaly, for where large tracts of country are shorn of their trees and forests, there the head-waters of our rivers fail or diminish. Evaporation is greatest from a shorn surface, and a country is on the road to ruin when its woodlands are mostly destroyed or consigned to the axe.

But woodlands require a change. Rotation is as necessary to the forest as to the successive crops of the farmer. We see this in the death of pines over large areas of this State. The idea that death was caused wholly by insects is fallacious. In it we see, in part at least, a natural effort to change the kind of vegetation. Oaks and hickory replace the pines. For hundreds of years pines had been the staple products of large tracts in this State. Is it therefore remarkable that a light soil containing the true pabulum of life for the pine, should have been nearly exhausted and the pine should have thereby become weakened and more liable to disease than formerly?

§ 39. The absolute weight of different soils is also variable. A cubic foot of clay, with its moisture, weighs about 115 pounds. The same quantity of damp sand 141; while peat, with its water, weighs only about 81 pounds. The weight of soils affects the labor of tillage. More force is required to lift a sandy soil than a clay. But the texture or compactness of an undrained clay soil more than makes up for its less weight.

In every point of view the farmer is encouraged to ameliorate the mechanical condition of his plantation. The first point requiring attention is its water or drainage, for when a soil is water soaked, good crops are only to be made in the most favorable season.

A subsoil of clay beneath sand is ameliorated by draining, though the top may appear to be sufficiently dry; for the clay may be regarded as a reservoir of water, just as the filled saucer beneath the flower pot.

§ 40. We may recognise in all these facts two currents which may be found in soils; a downward current, which disposes of surface water, and an upward current, when the surface water has become exhausted. This arrangement is a wise one, for if there were no upward currents plants would perish, both for want of nutriment and water during drouths. This result would be far more likely to happen in the case of the cereals and cultivated crops, than in the plants which grow naturally in the soil.

§ 48. The mechanical condition of a soil can rarely be ameliorated by mixture. Those which really require mixture are stiff clays and loose sands. If a mixture can be effected by the plow, it will no doubt pay. But it becomes quite questionable, whether a farmer can haul sand to mix with the clay, or clay to mix with the sand. The cost of hauling is too great. A gardner may make the necessary mixture. At any rate, before a farmer attempts to change a field of ten acres by mixing clay with sand, or the reverse, he had better count the cost beforehand. Now although a barren sand will not probably be benefitted by draining, yet the texture of the stiffest clays will be; and as clays are mixtures of silex and alumine, and as they are often, if not generally supplied with the alkalies and alkaline earths, the most direct as well as the cheapest mode to cure a clay of its stiffness, will be to remove the water by under drainage.

As it regards sand, it will be cheaper to employ calcareous fertilizers with forms of muck than to mix with it clay.

The theory of amendment by mixture is perfectly satisfactory; but in practice, it will be found a losing business, where either material has to be carted many rods.

§ 49. To recur once more to the subsoil plow in connexion with the clays too stiff to cultivate; it has been stated, that the subsoil plow should not be used until the land has been well drained. When considerable moisture exists in the clay, it unites and becomes solid and impervious, so that little benefit has been experienced in certain cases from subsoiling; but when the water has been drained off and the clays have become loose and porous, the masses raised by the plow still remain in this condition, or become still more porous, so that the beneficial effects of subsoiling a stiff under clay will not be secured till after the land has been well drained.

§ 50. It is scarcely necessary to speak of hoeing or the use of the cultivator. They are needful operations and no one omits them; but why hoe? is it simply to kill weeds? Hoeing kills weeds and pulverizes the soil, but it has an effect which is unseen except from its effects which are liable to be misinterpreted. The good effects of hoeing arise from the moist surface created, and which absorbs ammonia. That the beneficial effects do not all arise from the destruction of weeds and pulverization is evident from the fact that the more frequently the surface is stirred and a moist surface exposed, the more vigorous the growth of the crop. The properties of ammonia remove all doubts respecting the effects of hoeing. Let the vapor of hartshorn in a receiver or tumbler be placed over a vessel of quicksilver, and then introduce a mass of moist soil, and see with how much rapidity the whole of the ammonia will be absorbed by the moist soil. Ammonia always exists in the atmosphere, and it is obtained in dry weather by exposing a fresh surface of soil to the atmosphere. Hoeing is a cheaper way of obtaining ammonia than buying it in guano; we get it in dry weather, and it is agreeable to the experience of all good observers, that hoeing in dry weather is followed with greater benefits than if the weather is wet. Gardens are hoed more frequently than field crops, though it may be supposed that the vigorous growth in the former is due to a rich soil. Still, the good effects of hoeing are too demonstrable to the eye to admit of doubt. Hoeing, however, is laborious, and too much time is consumed to admit of its repetition in field crops. To supply the place of the hoe the cultivator comes in, and no doubt its more frequent employment in dry weather, not simply to kill weeds and break sods, but to create a moist surface which will absorb ammonia, and which is now known to be so needful to all crops. Dry surface has little or no absorbative power as may be shown by introducing a ball of dry earth into a tumbler, or receiver of hartshorn in vapor.

It is highly probable too, that a farmer might produce results as beautiful as the florist, by pursuing like means; applying his fertilizers in a state of extreme dilution, in which case it is evenly distributed to roots and in a state in which it can be taken up. Facts constantly occurring in the analysis of soils, favor, and even sustain the doctrine. For how much soluble matter is there in one thousand grains of soil? It is possible to obtain one and one and a half per cent, consisting of 12 to 14 substances. Nature seems to dole out her treasures; instead of dealing liberally as befitting her, she gives atoms. There are practical principles in the facts developed. If soluble substances are employed, they too must be dealt out in atoms only. A few atoms at a time only are found in solution in the soil. The vegetable organism is only fitted to receive atoms; and in this we see adaptations which must be repeated. It is true, turkeys, swine and men may be crammed and fattened; but this system will not succeed in raising wheat, cotton or corn.