inorganic food which plants require. Or it | given soil especially requires, is to be demight be a special exhaustion of some one termined by a joint consideration of the or two substances only, caused by the long kind of treatment to which the land has continued and successive growth of crops previously been subjected, and of its actual of the same kind of plant. composition, as determined by a rigorous chemical analysis. A familiar example will show how these different forms of exhaustion-both alike fatal to the fertility of the soil-may be severally produced. The grain, as we have seen, contains much phosphoric acid, and the straw much silica. Together they carry off largely from the soil all those substances for which the plant is dependent upon the soil. Carry away both straw and grain to market, and you year by year remove from the soil those things which feed both ear and straw-you will therefore gradually produce a general exhaustion. But return the straw to the soil again, in the form of manure, and you deprive it of those things only which are especially necessary to, and are present in, the grain you sell. Continue this, however, for a series of years as has been too much done in almost every country of Europe-and you will ultimately so rob the soil of those phosphates which abound in the grain, that your fields will cease to yield you a remunerating crop. The cause being known, the remedy is apparent. When the land is generally exhausted, a manure must be added which shall contain, and therefore convey to it, an adequate supply of all the things which all our crops and their parts conjointly, carry off. When it is specially exhausted, the addition of one or more of these substances will be sufficient. This principle throws further light also upon the rotation of crops. It is better to prevent the special exhaustion we have been speaking of than to cure it. It is often difficult to discover what the land really requires, and, therefore, to cure the evil when it exists. The only method of preventing it with which we are yet acquainted, is by the introduction of a skilful rotation or alternation of unlike crops. In adopting such a rotation, we only copy from nature. In the wide forest, many generations of broad-leaved trees live and die, and succeed each other; but the time comes at last when a general pestilence seems to assail them all-their tops droop and wither, their branches fall off, their trunks rot. They die out, and a narrowleaved race succeeds them. This race again has its life, of centuries perhaps ; but death seizes it too, and the expanded leaf of the beech, the ash, and the oak, again cheer the eye-playing with the passing zephyrs and glittering in the sun. So in the broad meadow, the old pasture changes, and new races of humble grasses succeed each other as the fields increase in age. The alternation of crops, therefore, asserts to itself something of the dignity of a natural law, and man is evidently in the right course when he imitates nature in a procedure like this. But upon what do its good effects depend? Why do the broad leaves alternate with the narrow in the ancient forest? Why do the grasses change in the old meadow? Why does the farmer obtain a larger produce, and for a greater number of years, by growing unlike crops alternately, than by continuing year after year to grow the same? It is not necessary now, as in the olden time, to add ton after ton of farm-yard manure, which contains a certain proportion of all that the plant requires, but does not specially abound, in the phosphates or other substances, which the soil may happen especially to be in want of. To add enough of these last, it may be necessary to lay on farm-yard manure in very large quantity, The reason is not merely that one crop and at a great cost, and after all the farmer carries off more, and another crop less, of may wonder that he has only imperfectly all those things which all our crops derive succeeded in restoring his worn out fields. from the soil, but that one crop carries off A knowledge of the composition of the ash, more of one thing, another crop more of shows us that the addition of one or two another. The grain carries off phosphorus, things may be sufficient to produce the desired the straw silica, the bulb alkaline matter. effect, and that the addition of these things After, perhaps, fifteen or twenty successive may often be made at a comparatively mod-crops of the same kind, the surface soil erate cost. What the things are which any * Phosphoric acid unites with lime, magnesia, &c., and forms Phosphates. through which the roots are spread becomes so poor in those substances which the crop specially requires, that the plant cannot obtain from it a sufficient supply to nourish and bring to maturity the full-grown plant, within the time allotted to it in our climate for its natural growth. The roots do their best; they collect as diligently as they can, but winter comes on, and the growth ends before the plant is fully matured. In the case of corn, the first effect of a scarcity, say of phosphoric acid, is to make the ear smaller and the number of grains less; the next to continue the growth into, the winter, and only when a very fine season occurs to ripen the ear at all. The addition of lime to the land has in nearly all well cultivated countries extensively prevailed at every period of authentic history. In Europe its use has been universal, and everywhere the same observation has been commonly made, and has become a proverb in almost every language. "Lime," the proverb says, "enriches the fathers, and impoverishes the sons." Laid on in repeated doses, and for a length of time, the luxu riant crops it raises at first gradually fall off, till at length even with the stimulus, as it is called, of larger doses, the land refuses to be excited. But suppose we alternate the corn crop, which in its grain carries off phosphoric acid, with a hay crop, which requires much A like result has been observed of late silica, or a root crop, to which much alkaline years from the application of gypsum, of matter is necessary-then the one crop nitrate of soda, of common salt, or of saltwould live upon and remove what the other petre. Their good effects were apparent had left in greater abundance. Instead of for a certain number of years, but they robbing the soil every year of the same substances, we should be exhausting it more equably of all, and we should be able, for double the time at least, to crop it without the risk of its ceasing entirely to give us a profitable return. We should gradually work up also every available substance in the soil, whether such as are naturally present in it, or such as we have ourselves added in the form of manure. gradually ceased to act, and the land was afterwards believed to be weaker and less productive than before. How are these results to be explained? Can this apparent exhaustion be prevented? Can it easily be remedied? Is it a necessary consequence of the use of lime, and of the other substances we have mentioned? Is the manure or the farmer to blame for the result? The plant carries away from the soil say ten substances. The soil is deficient in one of these, and the plant cannot grow. That one is lime or soda. You add it to the land, and your crops spring up luxuriantly. Rejoiced at this result, you add more lime, and your crops still grow well-for it requires the addition of three or four hundred bushels to an imperial acre to add one per cent. of lime to a soil which is twelve inches in depth. But after many crops, the lime at length ceases to benefit the land, the crops are even smaller than they were before lime was first added, and the farmer is at a dead stand. What is true of the simple alternation of a corn with a green crop, is more true still of a longer and more complicated rotation. The greater the variety of crops we grow, and the longer the interval between the successive crops of the same kind, the more perfectly do we avail ourselves of the benefits which an obedience to the suggestions of this principle is fitted to confer upon us. No rotation, it is true, however skilful, will alone prevent the land from becoming ultimately exhausted. Nothing but regular and generous manuring will do this, unless there be, in springs from beneath, or in the decaying fragments of rock mixed with the soil, or in substances brought down from Now what has he been doing all this higher grounds, or in the nature of the rains time? He has been adding one thing only that fall upon the land, some perennial in his lime-he has been carrying off ten in source of those substances which the crops his crops. Is it any wonder, then, that after always carry off from the soil. But in a a lapse of years, the land should become skilful rotation there is this virtue, that poor in one or more of the other nine? The land which is subjected to it cannot be ruin-iron-smelter throws into his furnace his ore ed in so short a time. If one tenant use it ill, it may come into the hands of another before the ruin is so far irremediable, that the farmer who has a rent to pay cannot reclaim it with a prospect of immediate profit to himself. But let us apply our principle next to the illustration of a well-known practical fact. and his coal, but he gets no metal until he puts in lime also. He adds a dose of lime, and he draws off a running of metal. He adds more lime, and he procures perhaps more iron. But he very soon finds that lime does no further good; he has melted out all the iron; he has exhausted his furnace; the stimulus of lime has no effect. He must add ore and coal again, and again he will obtain his periodical flows of metal So it is with the soil. The farmer who hopes by the continual addition of one thing, to make his land produce continual good crops, hopes and acts against reason. It is his fault that the land has become exhausted, and the cure is in his own hands. Lime, therefore, does not necessarily "impoverish the son." But any treatment will ultimately make the land poorer which does not return to the soil all the things which the crops have carried off, and at least in equal proportion. "But the land recovers from its exhaustion without any addition," says the farmer, "if I only leave it to itself for a sufficient length of time. So it does, no doubt, to a certain extent. The Deity is full of bounty to careless and ignorant and inconsiderate man, and makes all nature work to do him good, and to repair his often wilful waste. The rains brought by the sea-winds, shower down upon some spots an abundant supply of certain of those things which the crops carry off-it may be the very things in which the soil is deficient. Others, again, are replenished by springs from beneath, or by the crumbling of the rocky fragments which are mingled with their surface-soil, while on many spots the grasses and other herbage which spring up send down their hidden roots to the depths of the under soil, and slowly and gradually bring up and enrich the surface with a sufficient supply of those substances of which the numerous crops had robbed it. In all this we see infinite cause to revere the bounty and goodness of the ALL-DIRECTOR-none to justify the negligence or waste of the unskilful farmer. But from the inorganic portion or ash of the plant, let us now turn to that of the animal. The several parts of the animal body leave, when burned, a quantity of ashes. This we have already stated as establishing a general analogy between the plant and the animal. But the analogy is closer than this. For, first, the proportion of this ash varies in different parts of the animal as it does in those of the plant. The fresh bone leaves one half of its weight when burned, the fresh muscle not more than one hundredth part. Yet, as is the case with the plant, the small proportion present in the muscle is as essential to its constitution and healthy existence, as the huge quantity in the bone. The composition of each part is specially adapted to the purposes it is intended to serve. Again, of what substances does this ash consist? It contains the same substances as are present in the ash of the vegetable food which the animal eats. There are found in it potash, soda, lime, magnesia, oxide of iron, oxide of manganese, sulphur, phosphorus, and chlorine. Thus the analogy between the soil, the plant, and the animal, becomes closer and closer at every step. But there is a striking difference among the three in respect to their inorganic part. Thus it may be given as a general characteristic of each that The soil contains silica and alumina. The alumina gives consistence and tenacity to the soil; the silica gives strength and firmness to the stem of the plant. For such purposes, the animal does not require their aid, and, therefore, they do not enter into the constitution of the animal body. Looking back for a moment to the plant, we now see not only that all these substances are essential to the growth and existence of the plant, but why they are and must be so. In adorning and beautifying the earth, plants serve only a subsidiary purpose. It has, indeed, pleased the Deity to invest them with forms and colors which are grateful and refreshing to the eye of man, but to impart this gratification is not the end or purpose of their being. Their real function is to prepare and minister food to the animal races. Now, this function they could not perform, unless they contained all that is required to build up the several parts of the animal body. Is it not a beautiful provision, therefore, that plants should be unable to grow where they cannot procure that which it is their natural purpose and duty to procure for the animal? To the instructed ear, the plant seems to have acquired a voice. "I need not grow here. I should be of no use if I did. I should only cheat the senses of the unsatisfied animal, exhibiting the semblance without possessing the substance of its natural food." The soil, therefore, must contain all the substances we have named, because the plant refuses to grow without them; the plant must contain them all, because the animal could not live unless they were present in its vegetable food. How much stronger at every step becomes the likeness between the soil, the plant, and animal-how much closer their connection -how much more indissoluble the union [haps, lived over again more than once in that binds them together? plant, or flower, or animal. In from three to five years, the entire body is taken out and built in again with new materials. A continued activity prevails among the living agencies to which this hidden work is com away, just as if a single brick were every day taken out of an old wall, or a single wheel out of a watch, and its place supplied by another. When dry bone is burned, the ash that remains behind amounts to two-thirds of its weight, and consists almost entirely of those phosphates of lime and magnesia which we have already seen to be so abundantly pre-mitted. Every day a small part is carried sent in the ash of different varieties of grain. This bone-earth, as it is called, must exist in the soil. The plant draws it from the earth by its roots. The cow eats it in the herbage she crops from the fields, and parts with it again in the milk she produces to feed her young. The calf sucks the milk, and works up the phosphates it contains into the form of living bone, adding daily to their size and weight. Without bone, our present races could not exist. It forms the skeleton to which the soft parts are attached, and by which they are supported; but the life of the animal being at an end, the function of the bone, as a living thing, is discharged. It falls to the earth, and new plants take up its phosphates again, to send them forward on a new mission into the stomachs of other living and growing animals. How beautiful is all this! Into the purpose for which this change takes place, we do not at present enter: it is sufficient that the fact is certain. The body therefore requires constant supplies, at every period of its life, of all those things of which its several parts are built up. A portion is removed every day from the bones and muscles of the old animal, and is rejected in its dung. Its food, therefore, must be able to supply the materials out of which a new portion of bone or muscle may be formed. How interesting-how lofty, are the reflections which this fact awakens in connection with our frail being, and with our tenure of this mortal life! "We die daily," It may be reasonably asked, why the food receives here a new sense. Day by day we we eat, the bread and the flesh-meat alike, lay down in the dust a new portion of our should necessarily contain, at every period earthly substance. Day by day we gather of our lives, a certain supply of these phos- up the fragments of former bodies, to build phates. We can readily understand the up anew our wasting frames. How are we necessity for their presence in the milk thus daily reminded of our true origin,— and other natural food of young animals, "He formed man out of the dust of the which are daily adding to the size and earth;" of our true nature," Dust thou strength of their bones, but why need they art;" and of our speedy fate,-" To dust be eaten by animals which are full grown- shalt thou return." Our connection with in which the bones have already attained the dead earth is never for a moment their full size and weight? The explana- loosened. We draw upon it for our hourly tion of this is to be found in an interesting food. In the midst of our most vigorous law of animal existence. life, we are connected with it by a chain The bodies of animals are continually which cannot for a moment be broken. undergoing a series of invisible changes of It cannot be broken, that is, without cersubstance, of which they are entirely un-tain death. For what follows if we merely conscious. We look at our hand to day, attempt to loosen the natural bond between as we write, and we fancy it is the same in substance as it was yesterday, or last year -as it was ten years ago. The form of each finger, of each nail, is the same. Scars made in our infancy are still there. Nothing is altered or obliterated; and yet it is not the same hand. It has been renewed over and over again since the days of our youth. The skin, and flesh, and bone, have been frequently removed and replaced. And so it is, more or less, with our whole body. The arms and limbs that sustained us in our schoolboy struggles, are long since consigned to the dust, have, per the soil and the animal? The herbage which the cow eats draws phosphates from the soil. Suppose the soil to be deficient in these substances, then plants will grow upon it, which require little of them, and which will therefore contain little. If the cow be turned in upon these, she might possibly, by hard labor, extract from them enough of every thing she requires to keep her alive; but she has a calf to sustain also. She continues to form milk, therefore, to feed and nourish her calf; and, if necessary, she will even draw a daily portion from the substance of her own bones, to minister to the growing bones of her young. But this | vegetable food which shall either promote interesting provision is only temporary. It in the greatest degree the production of an is an adaptation in the economy of the cow, enriching milk, or shall make the growing suited to any sudden emergency by which bones of the calf stronger or slighter acthe health of the suckling might be endan-cording to the purpose for which we wish gered. Let the deficiency of bone-earth, to rear it. therefore, in the food continue, and mother Thus the manuring of the soil, the raisand young will become weak together-ing of corn and grass, the production of both will lessen in weight and strength-milk, the fattening of cattle, and the rearthey will droop and die. They cannot be ing of young stock-all the branches of huslong independent of the quality of the bandry-are connected together, are exdead earth on which they tread. plained in theory, and improved in practice, by the same easily intelligible principles. It is easy to see how, out of a beautiful principle like this, when once established, numerous practical applications and explanations of known facts should naturally flow. It is self-evident, that whatever is found in the ash of the healthy animal body must exist in the soil upon which animals are to find the means of living. If any of these are naturally absent or deficient in it, we may be quite sure that it is necessary to add them, and that the soil will reward us for the gift. Has our husbandry been of a kind to exhaust it of some of these things?-then these must be first restored, before it will again carry the same amount of stock, or feed as many men. Has the land, for instance, been long cropped with corn, the addition of bones which contain the phosphates may give corn crops again where they had ceased to grow, or may cause them to ripen where previously the climate was considered unpropitious. How often are the laws of nature blamed for what is due only to the ignorance or indolence of the cultivator! For the sake of clearness, we have hitherto dwelt solely upon the inorganic or incombustible part of soils, plants, and animals; let us now turn for a little to their organic part. 1. In the dry soil, the organic part forms from two to ten per cent. of the whole weight. It consists, as we have already stated, of the decaying fragments of animals and vegetables; and among the other uses which it serves, is that of supplying the plant with a portion of those substances out of which its organic part is built up. Of the way in which it performs this function, we do not at present speak. 2. In the dry plant, the organic part forms from 90 to 98 per cent. of the whole. As regards its quantity, therefore, it is of much more importance than the inorganic part; at all events, it is necessary to consider its nature, and the purposes it is intended to serve. a. If we take a quantity of saw dust, or chopped straw, or chaff, or bran, and boil it Or has the land been long submitted to first in water, and afterwards successively dairy husbandry, and does it now produce in vinegar, spirit of wine, and ether, each a poor herbage?-do the cows give little of these liquids will dissolve something out milk, and are the calves stunted?-then it of it; but by far the largest portion will reis probable, that the land has become poor main undissolved. This white insoluble in the materials of bones. A single milk cow matter forms the substance of the cells and removes from the soil every year in its vessels of plants, and is known by the name milk and annual calf, what is equivalent to of woody fibre. It is of great importance to fifty pounds of bone dust.* This must, af- the plant, and forms a large portion of its ter a time, affect the herbage; and through substance; but except in its very young state, it, the milk of the cow, and the growth of is, for the most part, indigestible in the stomthe calf. To add bone to the calf, therefore, ach of animals; and after being eaten, is you must add bone dust to the land. How principally rejected again in the excretions. curious is this! b. If wheaten flour be made into a Or if our cattle are stall fed, this know-dough, and if this dough be washed upon a ledge of what the animal requires teaches us sieve under a small stream of water, as to select our food according to the special circumstances of age, condition, &c., in which they may happen to be placed, or to the immediate purpose for which they are fed. We can readily select a kind of * JOHNSTON'S Elements, p. 272. long as the water passes through milky, a grey matter, resembling bird lime, will remain on the sieve, while the milky water will gradually deposit a white powder. This white powder is starch; the grey substance left in the sieve is gluten. |