Agricultural Chemistry. 299 



Thus 100 parts of nitrogen, as nitrate of soda, yielded upwards 

 of 90 per cent, more increase in the produce of hay than the same 

 quantity of nitrogen, as sulphate of ammonia. 



Again, an equal surface of meadow, manured for three succes- 

 sive years, first with sulphate of ammonia, then with nitrate of 

 lime, and lastly with nitrate of soda, yielded, for 100 parts of 

 nitrogen in the manure, the following increase of produce : — 



Nitrogen in Manure. Yielded increase of Produce. 



100 parts in the form of sulpliate of ammonia .. 3140 parts of hay. 

 „. „ nitrate of lime . . . . 2593 „ 



„ „ nitrate of soda .. .. 4870 „ 



The same quantity of nitric acid, which, united to lime, had 

 yielded 2593 lbs. of liay increase, yielded, when united to soda, 

 4870 lbs. of hay, that is, upwards of 90 per cent. more. 



These results prove irrefragably that the crops on a field, ma- 

 nured with ammoniacal salts or nitrates, is not proportional to 

 the supply of nitrogen in the manure ; for the same weights of 

 nitrogen in the same field give, not equal, but most unequal 

 crops. 



It follows farther, from these experiments, that if to the ammo- 

 niacal salts we add other substances, which by themselves are 

 capable of taking a part in vegetation, that is, which can serve as 

 food to plants : that, in this case, the proportion of the crop to 

 the nitrogen supplied in the manure must again be changed ; 

 because, to the action of the nitrogen in ammonia by itself, and 

 to that of the substance accompanying it in the salt, is added that 

 of a new factor. 



By manuring a meadow with 666 parts by weight of sal ammo- 

 niac and j)hosphate of lime, Kuhlmann oljtaincd, in 1844, 1845, 

 and 1846, an excess of produce over that of an equal surface of 

 unmanured land equal to 76^6 parts, liy weight, of hav. 



An equal surface, manured with 300 parts, by weight, of guano, 

 containing 5 per cent, of nitrogen, yielded, in the same years, an 

 increase of produce equal to 2469 parts, by weiglit, of hay. 

 From these results it appears that — 



Nitrogen in Manure. Yielded increase of I'rodnce. 



100 parts in the form of sal ammoniac .. .. 2,439 parts of hay. 

 „ „ sal ammoniac with )>hoa- 



j.hate of lime .." .. 4,307 



„ „ i^iiaiic. .. .. .. l(i,4G0 „ 



In 1840, in Kuhlman's experiments, 200 parts, l)v weight, of 

 sulphate of ammonia yielded an increase equal to 2533 parts of 

 hay : and an equal surface, wiiich received 200 parts of sulphate 

 of amiiioiiia, witii the addition (jf 133 parts of common salt, 

 yielded an increase equal to 3J 73 parts of liav. The significance 

 of these results is obvious and easilv understood. 



