ECONOMY OF FARMING. 



65 



changed into humus, and the humic acid so existing, not connected with a base, but 

 by water, is sucked in or evaporates, sutiering a more extended decomposition. But 

 it is also consuming, in that all the salts already found or first existing in the manure, 

 are soon carried deeper by water. To those soils which are consuming, belong the 

 dry, gravel, and sand soils, and in a lesser degree, also, the chalk and lime-stone soils. 

 The sand, and yet more the gravel soil, loses easiest of all soils the bodies existing 

 by the rotting of the manure, and which serve as nutriment for plants, and therefore 

 requires an often-repeated, but only weak manuring. 



"A soil is hungry, when it requires much manure to make it fruitful. To this class 

 belong all kinds of clay soil containing much iron, especially if they are moist. Sim- 

 ilar kinds of soil particularly require much manure, in that the humic-acid arising 

 from the decomposition of the manure is chemically connected with much alumine 

 and oxyde of iron, and that on account of the difficulty of decomposition of the exist- 

 ing humic acid salts (humate of alumine and oxy-humate of iron), the humic acid 

 is drawn from the plants." 



On p. 288 he says : '• The soil of the earth contains water in two different forms, 

 viz., in a chemical combination, as water of crystaUization, (as hydratic water) 

 and in a free state, or as capillary water (hygroscopic water)." 



'• The quantity of water chemically combined, depends principally on the quantity 

 of humic acid, humates, free alumine, and oxyde of iron, as these bodies contain much 

 water in chemical union. Besides, also, there is some hydratic water in silicious 

 earth, in gypsum and many other salts. It is in the highest degree probable that 

 plants need no water in chemical union, since their roots have no power to draw out 

 the hydrates. 



" The power of the earth to take up and hold back more or less water mechanically 

 in its pores, is of the greatest importance for vegetation, not only because the vyater 

 in and of itself contains the life of the plants, but especially, also, because it carries to 

 them means of nutriment from the soil. In the luant or excess of moisture, we frequently 

 must seek the cause of the unfruitfulness of the soil. The ease of the soil to hold mois- 

 ture, but especially the decompositions and combinations which take place, are of 

 importance, since the decomposition of the organic remains may be presented either 

 from the excess or the want of moisture. 



Professor Schubler, who tried many experiments as to the power of the earth 

 with reference to the taking up water in its pores, found the following results: 



" The humic acid has therefore the greatest power after magnesia ; still greater is 

 this power in the peaty soil, since 100 parts by weight will take up 300 to 360 parts by 

 weight of water in its pores, if it has been first artificially dried out." 



"By many experiments it has been ascertained, that most soils serving for the culti- 

 vation of grain possess a power of taking water into their pores of 40 to 70 percent. 

 If this power is much less or greater than these, the soil is more suitable for pines 

 and such like trees, and for grass cultivation. 



" To judge of the value of a soil in this respect, Ave must regard the climate, the 

 mean quantity of rain fallen, and the temperature ; as the same soil in one region may 

 be fruitful, while in yet another, under different circumstances, it is not so. A clay soil, 

 with great power of taking water into its pores (very porous), is desirable in a ho^ 



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