138 TALKS ON MANURES. 



Phosphoric acid 7.5 



Sulphuric acid 4.3 



Carbonic acid 18.0 



Silica 3.0 



Lime 30.0 



Magnesia 8.5 



Potash 30.0 



Soda, chloride of sodium, oxide of iron, sand, loss, etc 8.7 



100.0 



" Let us suppose the land to liave yielded four tons of clover-hay 

 per acre. According to the preceding data, we find that such a 

 crop includes 234 lbs. of nitrogen, equal to 273 lbs. of ammonia, 

 and 672 lbs. of mineral matter or ash constituents. 



In 672 lbs. of clover-ash, we find : 



Phosphoric acid 51i lbs. 



Sulphuric acid 39 " 



Carbonic acid 131 " 



Silica 30 " 



Lime 301 " 



Magnesia 57 " 



Potash 134i " 



Soda, chloride of sodium, oxide of iron, sand, etc 58 " 



672 Ib^ 



" Four tons of clover-hay, the produce of one acre, thus contain a 

 large amount of nitrogen, and remove from the soil an enormous 

 quantity of mineral matters, abounding in lime and potash, and 

 containing also a good deal of phosphoric acid. 



"Leaving for a moment the question untouched, whether the 

 nitrogen contained in the clover, is derived from the soil, or from 

 the atmosphere, or partly from the one, and partly from the other, 

 no question can arise as to the original source from which the 

 mineral matters in the clover produce are derived. In relation, 

 therefore, to the ash-constituents, clover must be regarded as one 

 of the most exhausting crops usually cultivated in this country. 

 This appears strikingly to be the case, when we compare the pre- 

 ceding figures with the quantity of mineral matters which an aver- 

 age crop of wheat removes from an acre of land. 



" The grain and straw of wheat contain, in round numbers, in 100 



parts : 



Grains of 

 Wheat. Straw. 



Water 15.0 16.0 



Nitrogenous substances, flesh-forming matter)* 11.1 4.0 



Non-nitrogenous substances 73.3 74.9 



Mineral matter, (ash) 1.7 5.1 



100.0 100.0 



* Containing nitrogen 1.78 .64 



