29.8 Agricultural Chemistry. 



ments of nutrition as it •would have lost, without ammonia, in 

 100 years. 



By this application of ammonia, the field will not have pro- 

 duced more wheat, on the whole, than it would have produced 

 without ammonia, but only more in the same time. 



We can now understand, that the total produce of our fields, or 

 their fertility , must he proportional to the sum of the mineral ele- 

 ments of nutrition contained in the soil, and that the amount or 

 weight of the produce in a given time is proportional to the rapidity 

 of the action of these mineral elements in that time. 



The experiments hitherto made in farming, in reference to 

 this point, have never been made with ammonia alone, or with 

 nitric acid alone, but always with ammoniacal salts, and nitrates, 

 that is, salts of nitric acid. 



Now it is evident that if the acids which accompany ammonia 

 in the ammoniacal salts, and the bases which accompany nitric 

 acid in the nitrates, take a certain share in vegetation, they must 

 in that case act precisely as if the sum of terrestrial elements 

 had been increased, or their action accelerated, that is, increased 

 in a given time. The effect of the ammonia or nitric acid must 

 be essentially modified by the presence of the accompanying 

 substances, according to the deficiency or excess of these in the 

 soil. If an excess of sulphuric acid be present in the soil, then 

 ammonia, accompanied by sulphuric acid, will exert a less 

 influence, or yield a less produce, than muriate of ammonia 

 would do if there were a deficiency of muiiatic acid in the soil. 



The crops on fields manured with ammoniacal salts or nitrates 

 can therefore never be proportional to the supply of nitrogen in 

 the manure, but must rise and fall according to the nature and 

 action of the substances supplied along with it. The most 

 beautiful and convincing experiments, in regard to these essential 

 questions, were made in the years 1843-46, by F. Kuhlmann of 

 Lille, and Schattenmann ('Comptes Rendus,' vol. xvii. p. 1121; 

 « Ann. de Ch. et de Ph.,' vol. xviii. p. 143 ; ih. p. 279). These 

 experiments are hardly known in agricultural circles, and I 

 therefore give them here in detail. They have contributed not 

 a little to render immoveable my conviction of the truth of the 

 doctrines I hold. 



By manuring a meadow with ammonia and nitrates, Kuhlmann 

 obtained an increase in the produce of hay, in 1843, which, 

 calculated for 100 parts of nitrogen, was as follows, for equal 

 surfaces : — 



Nitrogen in the Manure. Produced increase in Crop. 



100 parts in tlie form of sal ammoniac .. .. 2439 parts of hay. - 

 „ „ sulphate of ammonia .. 2160 „ 



nitrate of soda . . . . 4005 „ 



