156 REPOET OF THE COMMISSIONER OF AGRICULTURE. 



Knopp, Henneberg, Stolunan, Brustlein, Peters, Voelckers, Warring- 

 ton, aud other chemists. 



These several investigations have shown that the property or ab- 

 sorbing, retaining, and modifying the composition of manures belongs 

 to every soil in a greater or less degree. 



ABSORPTION OF AM]U:0NIACA1, SALTS BY VARIOUS SOILS. 



The ammonia floating in the atmosphere is continually being waf*h«Hl 

 into the soil carried into it by the rains. The clay, oxide of iron, and 

 the organic matter contained in the soils, perform the important func- 

 tion of absorption. This property of clay may be one of the reasons 

 why clay lands are more suitable to wheat than are sandy soils. Al- 

 though clay has this property of retaining more of these alisorbed sub- 

 stances than sands or loams, yet it is evident that these latter soils must 

 receive the same amount of fertilizing matter from the rains, only they 

 have less ability for retaining or storing it up. 



In regard to the absorption of ammonia and its salts by various soils, 

 the following summary is taken from Dr. Voelckers' paper " On the 

 chemical properties of soils : "• 



(1) All of the soils experimented upon had the power of absorbing ammonia from 

 its solution in water. 



(2) Ammonia is never completely removed from its solution, however weak it may 

 be. On passing a solution of ammonia, whether weak or strong, through any kind of 

 soil> a certain quantity of ammonia invariably passes through. No soil has the power 

 of fixin g completely the ammonia with which it is brought in contact. 



(3) The absolute quantity of ammonia which is absorbed by a soil is larger when a 

 stronger solution of ammonia is passed through it, but relatively weaker solutions are 

 more thoroughly exhausted than stronger ones. 



(4) A soil which has absorbed as much ammonia as it will from a weak solution, 

 takes up a fresh quantity of ammonia when it is brought into contact with a stronger 

 solution. * 



(5) In passing solutions of salts of ammonia tlirough soils, the ammonia alone is ab- 

 sorbed, and the acids pass through, generally, in combination with lime, or, when 

 lime is deficient in the soil, in combination with magnesia or other mineral bases, 



(6) Soils absorb more ammonia from stronger than from weaker solutions of sul- 

 phate of ammonia, as of other ammonia salts. 



(7) In no instance is the ammonia absorbed by soils from solutions of free ammonia, 

 or from salts of ammonia, so completely or permanently fixed as to prevent water from 

 washing out appreciable quantities of ammonia. 



(8) The proportion of ammonia which is removed in the several washings is small 

 in proportion to that retained by the soil. 



(9) The power of soil to absorlj ammonia from solutions of free or combined ammonia 

 i» thus greater than the power of water to redissolve it. 



It may be concluded from the above that in ordinary seasons no fe^rs 

 need be entertained that occasional heavy rain storms will remove much 

 ammonia from ammoniacal top-dressings, such as sulphate of ammonia, 

 soot, guano, and similar manures, but in excessively rainy seasons or in 

 disujcts that have a large rainfall considerable quantities ma> be re- 

 moved from land top-dressed with ammomacaJ manures, even iu the case 

 of stiff clay lauds. 



GENERAL CONCLUSIONS IN REGARD TO THESE POWERS. 



The general conclusion that may be drawn from the different investi- 

 gations show that when the surface waters charged with the products 

 of vegetable decay are brought into contact with argillaceous sediment, 

 they part to some extent with their potash, ammonia, silica, i)hosphorio 



* Jour. Boyal Agricultnial Society, vol. zxi, p. 123. 



