ECONOMY OF FARMING. 119 



condition of the field in which it is left by the culture of the preceding 

 fruit shall be most suited to the succeeding fruit, and most profitable for 

 itself. 



14. Those plants bear the most manure which form a thick and stiff 

 stalk, or grow low in the field, moreover all root-vegetables. To these 

 belong maize, beans, head-cabbage, hemp, potatoes, turnips, &ic., he. 



Culmiferous grain (i. e. having a haulm or hollow-jointed stalk,) easily suffers 

 injury from fresh manure, as it shoots up too tender and too high, easily lodges, 

 and has feeble ears, or becomes rusty and blighted ; whilst maize, and beaiis, head- 

 cabbage, and the root-vegetables, yield in the same proportion a greater product ac- 

 cording as one employs the more manure for these fruits. 



15. The usual culmiferous and pod-bearing plants need less manure, and 

 buckwheat the least. 



16. But above all, the amount of the product of all the plants is in ex- 

 act proportion to the amount of those before-existing in the soil in a dis- 

 solved state, assimilating to themselves a quantity of organic nutriment of 

 plants ; and we shall obtain a harvest so much the richer, the more we take 

 care that the field shall always contain that quantity of manure which is 

 most suited to the nature of the plants. 



Many are of the opinion that one kind of grain needs more, another less manure, 

 not so much in an absolute as in a relative point of view, in order to produce a defi- 

 nite weight of straw and grain ; others suppose that plants assimilate to themselves 

 difterent parts of the humus, and that we must ascribe it to this last circumstance, 

 that we suffer first wheat and then oats to follow one another in the field ; and others 

 still, that a course of fruits with a proportionate succession, with a given manuring 

 will produce more organic matter than with a disproportionate one. But I hold on 

 this subject, that the product of all fruits is greater in the same mass, as they find in 

 the soil more humus in a state easy to be dissolved, which they suck in, and out of 

 which they form the different particular parts of plants. On this account only, we cause 

 wheat to come in the field earlier after the manuring than oats, because the increased 

 product of the wheat-plants in a strong field, has a greater cash-value than that which 

 the oat-plant produces, though this generally produces a greater volume, and is earlier 

 in a rich soil and later in a poorer soil. Plants, like beasts, first take the nourishment 

 appointed for them to themselves, arid then secrete in their interior parts, by assimi- 

 lation, those substances which they need for the formation of the organic material ; 

 and as from hay, with the cow, is formed milk, with the fattening-ox, tallow, and with 

 the sheep, wool, by the process of life of the beasts ; so from the same hunms dissolved 

 in water, according as a plant sucks it in, a vegetable product contains sometimes 

 more, sometimes less gluten, farina, sugar, slime, oil, &c. But this product is al- 

 ways in that proportion of quantity which corresponds to the amount of dissolved 

 humus in the soil. 



[LiEBiG pronounces the theory respecting the rotation of crops, the only one which 

 rests on a firm basis. Decandolle supposed that the roots of plants, in extracting so- 

 luble matter of various kinds from the soil, absorbed a variety of substances which 

 were not fitted for their own nutriment, and that therefore these were ejected, and re- 

 turned back to the soil. Of course, the soil thus filled with this ejected matter would 

 be unfit for another crop of the same plant. But these very substances might be a 

 suitable nutriment to other plants of a diflerent species, and by being absorbed from 

 the soil it might again be rendered proper for the plants before raised on it. He cites 

 as confirmatory of this theory also the experiments of Macaire Princep. This theory 

 of Decandolle, and also the one to which our Author alludes above, which merely 

 considers the innutritions matter as not at all extracted from the soil, but left in it, 

 Leibig thinks do not explain how afield is improved by lying fallow, and this accord- 

 ing as it is improved, nor how a soil gives carbonaceous matter by the cidtivation 

 of luzerne and sainfoin. He says that the advantage of the alternation of crops pro- 

 ceeds from two causes: '• A fertile soil ought to afford to a plant all the inorganic 

 bodies indispensable for its existence in sufficient quantity and in such a condition 

 as allows their absorption." 



