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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 A familiar example will show how these chemical analysis. different forms of exhaustion—both alike This principle throws further light also fatal to the fertility of the soil—may be upon the rotation of crops. It is better to severally produced. The grain, as we have prevent the special exhaustion we have been seen, contains much phosphoric acid, and speaking of ihan to cure it. It is often the straw much silica. Together they carry difficult to discover what the land really reoff largely from the soil all those substances quires, and, therefore, to cure the evil for which the plant is dependent upon the when it exists. The only method of presoil. Carry away both straw and grain to venting it with which we are yet acquaintmarket, and you year by year remove from ed, is by the introduction of a skilful rotathe soil those things which feed both ear tion or alternation of unlike crops. and straw-you will therefore gradually In adopting such a rotation, we only copy produce a general exhaustion. But return from nature. In the wide forest, many the straw to the soil again, in the form of generations of broad-leaved trees live and manure, and you deprive it of those things die, and succeed each other ; but the time only which are especially necessary to, comes at last when a general pestilence and are present in, the grain you sell. seems to assail them all their tops droop Continue this, however, for a series of and wither, their branches fall off, their years—as has been too much done in al- trunks rot. They die out, and a narrowmost every country of Europe—and you leaved race succeeds them.
This race will ultimately so rob the soil of those phos- again has its life, of centuries perhaps ; but phates* which abound in the grain, that death seizes it too, and the expanded leaf your fields will cease to yield you a remu- of the beech, the ash, and the oak, again nerating crop.
cheer the eye-playing with the passing The cause being known, the remedy is zephyrs and glittering in the sun. So in apparent. When the land is generally ex- the broad meadow, the old pasture changes, hausted, a manure must be added which and new races of humble grasses succeed shall contain, and therefore convey to it, each other as the fields increase in age. The an adequate supply of all the things which alternation of crops, therefore, asserts to all our crops and their parts conjointly, itself something of the dignity of a natural carry off. When it is specially exhausted, law, and man is evidently in the right course the addition of one or more of these sub- when he imitates nature in a procedure like stances will be sufficient.
this. It is not necessary now, as in the olden But upon what do its good effects depend? time, to add ton after ton of farm-yard ma- Why do the broad leaves alternate with the nure, which contains a certain proportion narrow in the ancient forest? Why do the of all that the plant requires, but does not grasses change in the old meadow? Why specially abound, in the phosphates or other does the farmer obtain a larger produce, substances, which the soil may happen es- and for a greater number of years, by growpecially to be in want of. To add enough ing unlike crops alternately, than by conof these last, it may be necessary to lay on tinuing year after year to grow the same? 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 through which the roots are spread becomes
so poor in those substances which the crop * Phosphoric acid unites with lime, magnesia, specially requires, that the plant cannot ob&c., and forms Phosphutes.
tain from it a sufficient supply to nourish and
bring to maturity the full-grown plant, with- The addition of lime to the land has in in the time allotted to it in our climate for nearly all well cultivated countries extenits natural growth. The roots do their best ; sively prevailed at every period of authentic they collect as diligently as they can, but history. In Europe its use has been uniwinter comes on, and the growth ends before versal, and everywhere the same observation the plant is fully matured. In the case of has been commonly made, and has become corn, the first effect of a scarcity, say of a proverb in almost every language. “Lime,” phosphoric acid, is to make the ear smaller the proverb says, “enriches the fathers, and and the number of grains less; the next to impoverishes the sons.” Laid on in repeatcontinue the growth into the winter, and ed doses, and for a length of time, the luxu. only when a very fine season occurs to ripen riant crops it raises at first gradually fall off, the ear at all.
till at length even with the stimulus, as it But suppose we alternate the corn crop, is called, of larger doses, the land refuses which in its grain carries off phosphoric to be excited. 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 sub- gradually ceased to act, and the land was stances, we should be exhausting it more afterwards believed to be weaker and less equably of all, and we should be able, for productive than before. double the time at least, to crop it without How are these results to be explained ? the risk of its ceasing entirely to give us a Can this apparent exhaustion be prevented ? profitable return. We should gradually Can it easily be remedied ?
Is it a neceswork up also every available substance in sary consequence of the use of lime, and the soil, whether such as are naturally pre- of the other substances we have mentioned ? sent in it, or such as we have ourselves Is the manure or the farmer to blame for added in the form of manure.
the result? What is true of the simple alternation of The plant carries away from the soil say a corn with a green crop, is more true still ten substances. The soil is deficient in one of a longer and more complicated rotation. of these, and the plant cannot grow. That The greater the variety of crops we grow, one is lime or soda. You add it to the land, and the longer the interval between the and your crops spring up luxuriantly. Resuccessive crops of the same kind, the more joiced at this result, you add more lime, and perfectly do we avail ourselves of the bene- your crops still grow well—for it requires fits which an obedience to the suggestions the addition of three or four hundred bushels of this principle is fitted to confer upon us. to an imperial acre to add one per cent. No rotation, it is true, however skilful, will of lime to a soil which is twelve inches in alone prevent the land from becoming ulti-depth. But after many crops, the lime at mately exhausted. Nothing but regular and length ceases to benefit the land, the crops generous manuring will do this, unless there are even smaller than they were before lime be, in springs from beneath, or in the de- was first added, and the farmer is at a dead caying fragments of rock mixed with the stand. 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 and his coal, but he gets no metal until he ill, it may come into the hands of another puts in lime also. He adds a dose of lime, before the ruin is so far irremediable, that the and he draws off a running of metal. He farmer who has a rent to pay cannot reclaim adds more lime, and he procures perhaps it with a prospect of immediate profit to more iron. But he very soon finds that himself.
lime does no further good; he has melted But let us apply our principle next to the out all the iron; he has exhausted his furillustration of a well-known practical fact. nace; the stimulus of lime has no effect. He must add ore and coal again, and again Again, of what substances does this ash he will obtain his periodical Aows of metal consist? It contains the same substances
So it is with the soil. The farmer who as are present in the ash of the vegetable hopes by the continual addition of one thing, food which the animal eats. There are to make his land produce continual good found in it potash, soda, lime, magnesia, crops, hopes and acts against reason. It is oxide of iron, oxide of manganese, sulphur, his fault that the land has become exhausted, phosphorus, and chlorine. Thus the analogy and the cure is in his own hands. Lime, between the soil, the plant, and the animal, therefore, does not necessarily " impoverish becomes closer and closer at every step. the son." But any treatment will ultimately But there is a striking difference among make the land poorer which does not return the three in respect to their inorganic part. to the soil all the things which the crops have Thus it may be given as a general characcarried off, and at least in equal proportion. teristic of each that “ But the land recovers from its exhaus
The soil contains silica and alumina. tion without any addition," says the farmer, “if I only leave it to itself for a sufficient
The plant contains silica and no alumina.
The animal contains neither silica nor alulength of time. So it does, no doubt, to a
mina. certain extent. The Deity is full of bounty to careless and ignorant and inconsiderate The alumina gives consistence and tenaman, and makes all nature work to do him city to the soil; the silica gives strength good, and to repair his often wilful waste. and firmness to the stem of the plant. For The rains brought by the sea-winds, shower such purposes, the animal does not require down upon some spots an abundant supply their aid, and, therefore, they do not enter of certain of those things which the crops into the constitution of the animal body. carry off—it may be the very things in which Looking back for a moment to the plant, the soil is deficient. Others, again, are we now see not only that all these substances replenished by springs from beneath, or by are essential to the growth and existence of the crumbling of the rocky fragments which the plant, but why they are and must be so. are mingled with their surface-soil, while In adorning and beautifying the earth, on many spots the grasses and other herbage plants serve only a subsidiary purpose. It which spring up send down their hidden has, indeed, pleased the Deity to invest them roots to the depths of the under soil, and with forms and colors which are grateful slowly and gradually bring up and enrich and refreshing to the eye of man, but to the surface with a sufficient supply of those impart this gratification is not the end or substances of which the numerous crops purpose of their being. Their real function had robbed it. In all this we see infinite is to prepare and minister food to the animal cause to revere the bounty and goodness of races. the all-DIRECTOR --none to justify the neg- Now, this function they could not perligence or waste of the unskilful farmer. form, unless they contained all that is re
quired to build up the several parts of the But from the inorganic portion or ash of animal body. Is it not a beautiful provision, the plant, let us now turn to that of the ani- therefore, that plants should be unable to mal. The several parts of the animal body grow where they cannot procure that which leave, when burned, a quantity of ashes. it is their natural purpose and duty to proThis we have already stated as establishing cure for the animal? To the instructed ear, a general analogy between the plant and the plant seems to have acquired a voice. the animal. But the analogy is closer than “ I need not grow here. I should be of no this. For, first, the proportion of this ash use if I did. I should only cheat the senses varies in different parts of the animal as it of the unsatisfied animal, exhibiting the does in those of the plant. The fresh bone semblance without possessing the substance leaves one half of its weight when burned, of its natural food.” The soil, therefore, the fresh muscle not more than one hun- must contain all the substances we have dredth part. Yet, as is the case with the named, because the plant refuses to grow plant, the small proportion present in the without them; the plant must contain them muscle is as essential to its constitution and all, because the animal could not live unless healthy existence, as the huge quantity in they were present in its vegetable food. the bone. The composition of each part is How much stronger at every step becomes specially adapted to the purposes it is in- the likeness between the soil, the plant, and tended to serve.
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 When dry bone is burned, the ash that to five years, the entire body is taken out remains behind amounts to two-thirds of its and built in again with new materials. A weight, and consists almost entirely of those continued activity prevails among the living phosphates of line and magnesia which we agencies to which this hidden work is comhave already seen to be so abundantly pre- mitted. Every day a small part is carried sent in the ash of different varieties of away, just as if a single brick were every grain. This bone-earth, as it is called, day taken out of an old wall, or a single must exist in the soil. The plant draws it wheel out of a watch, and its place supplied from the earth by its roots. The cow eats by another. it in the herbage she crops from the fields, Into the purpose for which this change and parts with it again in the milk she pro- takes place, we do not at present enter: it duces to feed her youny. The calf sucks is sufficient that the fact is certain. The the milk, and works up the phosphates it body therefore requires constant supplies, contains into the form of living bone, add- at every period of its life, of all those things ing daily to their size and weight. With of which its several parts are built up. A out bone, our present races could not exist. portion is removed every day from the bones It forms the skeleton to which the soft parts and muscles of the old animal, and is re. are attached, and by which they are sup-jected in its dung. Its food, therefore, ported; but the life of the animal being at must be able to supply the materials out of an end, the function of the bone, as a living which a new portion of bone or muscle may thing, is discharged. It falls to the earth, be formed. and new plants take up its phosphates again, How interesting-how lofty, are the reto send them forward on a new mission into flections which this fact awakens in connecthe stomachs of other living and growing tion with our frail being, and with our tenanimals. How beautiful is all this! ure 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 the soil and the animal? The her bage substance as it was yesterday, or last year which the cow eats draws phosphates from -as it was ten years ago. The form of the soil. Suppose the soil to be deficient each finger, of each nail, is the same. in these substances, then plants will grow Scars made in our infancy are still there. upon it, which require little of them, and Nothing is altered or obliterated; and yet which will therefore contain little. If the it is not the same hand. It has been re- cow be turned in upon these, she might newed over and over again since the days possibly, by hard labor, extract from thein of our youth. The skin, and flesh, and enough of every thing she requires to keep bone, have been frequently removed and re- her alive ; but she has a calf to sustain also. placed. And so it is, more or less, with She continues to form milk, therefore, to our whole body. The arms and limbs that feed and nourish her calf; and, if necessustained us in our schoolboy struggles, are sary, she will even draw a daily portion from long since consigned to the dust, have, per- 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 togethering 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 ex. dead earth on which they tread.
plained in theory, and improved in practice, It is easy to see how, out of a beautiful by the same easily intelligible principles. principle like this, when once established, For the sake of clearness, we have numerous practical applications and expla- hitherto dwelt solely upon the inorganic or nations of known facts should naturally incombustible part of soils, plants, and flow. It is self-evident, that whatever is animals; let us now turn for a little to their found in the ash of the healthy animal body organic part. must exist in the soil upon which animals 1. In the dry soil, the nrganic part are to find the means of living. If any of forms from two to ten per cent of the whole these are naturally absent or deficient in it, weight. It consists, as we have already we may be quite sure that it is necessary stated, of the decaying fragments of animals to add them, and that the soil will reward and vegetables; and among the other uses us for the gift. Has our husbandry been which it serves, is that of supplying the of a kind to exhaust it of some of these plant with a portion of those substances out things ?—then these must be first restored, of which its organic part is built up. Of before it will again carry the same amount the way in which it performs this function, of stock, or feed as many men.
we do not at present speak. Has the land, for instance, been long 2. In the dry plant, the organic part cropped with corn, the addition of bones forms from 90 to 98 per cent. of the whole. which contain the phosphates may give As regards its quantity, therefore, it is of corn crops again where they had ceased to much more importance than the inorganic grow, or may cause them to ripen where part; at all events, it is necessary to consipreviously the climate was considered un- der its nature, and the purposes it is intendpropitious. How often are the laws of ed to serve. nature blamed for what is due only to the a. If we take a quantity of saw dust, or ignorar.ce or indolence of the cultivator ! 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 long as the water passes through milky, a circumstances of age, condition, &c., in grey matter, resembling bird lime, will rewhich they may happen to be placed, main on the sieve, while the milky water or to the immediate purpose for which they will gradually deposit a white powder. are fed. We can readily select a kind of This white powder is starch; the grey sub* Johnston's Elements, p. 272.
stance left in the sieve is gluten.