ECONOMY OF FARMING. 57 



According to Schubler, of 10,000 parts of water, 108 evaporated from humus in the 

 same time that 245 escaped from 313 of garden earth. He fixes the power of liumus 

 to retain warmth at 49, while Crome sets it down at 0.72. It has httle cohesive 

 power ; if set out in the open air, of all the integral parts of the soil it absorbs the 

 most moisture. AccortUng to Schubler. 1000 grains of humus in 48 hours absorbed 

 110 grains of water. According to Korte, in 4 weeks it absorbed 6 times as much 

 moisture. Of all the constituents of the soil it is most easily decomposed in the air, 

 and absorbs a great portion of its acids. According to Schubler, in a moist state, 

 of 0.21 of oxygen existing in air, it absorbed | in 30 days. 



" Humus, combined with oxygen, is soluble in water ; and a portion of the carbon 

 of humus unites itself, with the oxygen, to carbonic acid gas. It becomes warm, when 

 set out in the sun, very rapidly and strongly ; but it also very rapidly loses its acquired 

 warmth : it is especially found in the upper strata of the earth." 



The combinations of humus with ditferent soils, clayey, sanJy, &c., deserve the 

 attention of the agriculturist, but the subject is too extensive to be entered on in 

 these brief notes. 



Liebig, speaking with reference to the action of humus on plants, says: ''The 

 opinion that the substance called humus is extracted from the soil by the roots of 

 plants, and that the carbon entering into its composition serves in some form or other 

 to nourish its tissues, is so general and firmly established, that hitherto any nev7 argu- 

 ment in its favor has been considered unnecessary ; the obvious difference in the 

 growth of plants, according to the known abundance or scarcity of humus in the soil, 

 seemed to afford incontestable proof of ils correctness. Yet this position, when sub- 

 mitted to a strict examination, is found to be untenable, and it becomes evident, from 

 most conclusive proofs, that humus, in the form in which it exists in the soil, does not 

 yield the smallest nourishment to plants." He enters into such an examination, and 

 proves that the carbon of plants must be derived exclusively from the atmosphere, 

 where it only exists as carbonic acid, and of course in combination with oxygen. 

 He also shows that the carbon of the atmosphere is more than adequate to all these 

 purposes. The influence of humus upon vegetation, he states to be, that " humus does 

 not nourish plants by being taken up and assimilated in its unaltered state, but by 

 presenting a slow and lasting source of carbonic acid, which is absorbed by the roots, 

 and is the principal nutriment of young plants at a time when, being destitute of 

 leaves, they are unable to extract food from the atmosphere." 



In reference to humus and to soils, Sprengel remarks in his most able work on 

 soils (Die Bodenkunde), p. 133, " To the growth of plants 18 or 19 elementary sub- 

 stances belong, and as whilst frequently one plant needs more of this or that substance 

 for its success than another, so a soil may be poor for this plant while it is rich for 

 another, according to the rule that a soil is the richest or most fruitful for our cultivated 

 plants which contains the most humus, and much easily dissolved humic acid ; whilst 

 that is the poorest or most unfruitful which contains little humus, and from which few 

 or scarcely any other bodies than silicious earth allow themselves to be withdrawn 

 by water." 



A distinction has been supposed to exist between a rich and a fruitful soil. "By 

 a rich soil is understood such a one as contains a great quantity of humus or organic 

 remains, whether already prepared or not for the nutriment of plants. By a fruitful 

 soil we understand, on the contrary, that in which the humus is already fully prepared, 

 or in a soluble state for the nutriment of plants." This view Sprengel pronounces 

 not wholly correct, since it is derived from an incorrect representation which is 

 generally made of humus and the nutriment of plants generally. The peat soil, for 

 instance, he says, contains much humus soluble in water, and is lor the most part 

 very unfruitful. Among his analyses of soils we find two of portions of very fruitful 

 soil from near the Ohio river. These may be interesting to some of our readers. 



1. " From the low alluvial soil on the Ohio river, distinguished for extraordinary 

 fertility 



Parts by weight. 



100,000 parts by weight of the earth consist of 



Silicious earth and very fine quartz sand, 79,538 



Alumine, 7.3O6 



Oxyde of iron and oxydulated iron (oxydul) — much magnetic iron sand, — 5,824 



Oxyde of manganese, 1,320 



Calcareous earth, 0,619 



Magnesia, 1,024 



Potash — a great part of it in union with silicious earth — . . . 0.200 



8 



