ECONOMY OF FARMING. 63 



before mentioned, that the great effect of the humus is to furnish a supply of carbonic 

 acid to the plants, though Liebig's theory is disputed by some — Tr. j 



5. The same quantity of manure produces, therefore, in the course of 

 the time of its decomposition, a greater product of plants in a clayey than 

 in a sandy soil, provided the warmth of the climate is in a suitable propor- 

 tion to the tightness of the soil. 



Herein consists the essential cause that the product of the sandy soil is every- 

 where so small, and that a clayey soil, with an equal cost of manure, yields a greater 

 product. II a person would raise grain on a sandy soil continuously with profit, he 

 needs extraordinary aids ; either such a rotation of crops in which a certain extent is 

 devoted to the culture of plants for fodder, or ii^ the field is only sown with grain, then 

 are large pastures, foreign materials for litter, and much meadow requisite. If a man 

 has not these, the product of the field will diminish from year to year, and finally, it 

 will be necessary to let a part of the field lie fallow, in order to hold at his com- 

 mand the requisite aid to keep the other under cultivation, or he must lay out artificial 

 pastures, and try the Koppel-system of husbandry.— (See 6 : 7, 9, 27, below.) 



6. In a cold climate we generally use for the production of the same 

 crop more manure than in a warmer, and more in a heavy tiian in a mellow 

 soil ; because the dissolution of the humus is less favored in the former of 

 these cases, and the cold soil must be warmed by the greater quantity of 

 manure. 



The manure does not itself directly warm the soil, for the decomposition goes on 

 in the field so slowly that the warmth which is thereby occasioned is imperceptible : 

 it only takes place indirectly, because, not reflecting back the sun's rays, it absorbs 

 their warmth and imparts it to the surrounding earth. Hence the reason that one 

 notices no extraordinary accumulation of humus in the oft-manured fields of high and 

 coldly-situated countries, must be ascribed to their inclined position on the mountains, 

 in which a greater part of the dissolved manuring substances is carried away by the 

 rain. On the plains, we always observe an accumulation of black mould. 



7. By how much the more the humus is rendered easy of decomposition 

 by the repeated ploughing and loosening of the earth, by so much the more 

 easily it gives itself out of the soil. 



When a more excellent grain grows after an unmanured fallow than one obtains 

 with such fallow preparation, the reason of this is partly from the green manure which 

 exists there, often, indeed, in a small quantity, and in a great measure from the 

 dissolution of the old humus, which, by the repeated upturning of the soil in all 



fiarts of the strata of the earth, is brought into connexion with the air, and heat and 

 ight. But we always observe that those farms which lie fallow three years, and the 

 fallow field is wholly manured, as well as those which lie fallow twice in six years, 

 and are only once manured, produce less in proportion to the manure expended on 

 them than those which, with like amount of manure, are not suffered to lie idle ; from 

 which we may undoubtedly conclude, that a great part of the humus evaporates 

 uselessly by the labor on the fallow. If the plants are hoed and hilled, they give, 

 unquestionably, a greater product than if these labors of culture are neglected, since 

 thus the dissolution of the humus is aided, and it is brought by the hilling into the 

 nearest vicinity of the plants. But because at the hilling the plants are in their 

 greatest growth, therefore all the dissolved nutriment is for their benefit which cannot 

 be in the case of a fallow, since in the same years when the field is often tilled with 

 the greatest care, and is manured already in the summer, the seed first comes into it 

 in the autumn, and all the manuring substances which were dissolved in the first 

 years, can only in a small part be sucked in by the tender plants, and must therefore 

 evaporate uselessly. Fruit that is hoed gives a greater product, but in a larger pro- 

 portion draws nourishment from the soil, than that which is not hoed ; because by this 

 loosening a great part of the humus is evaporated before it is sucked in by the roots 

 of the plants. The proportionally greater need of manure there is in those farms 

 which cultivate much hoed fruit, is therefore not only to be ascribed to the larger 



