138 TALKS OX MANURES. 



Phosphoric acid 7.5 



Sulphuric acid 4.3 



Carbonic acid 18.0 



Silica 3.0 



Lime 30.0 



Magnesia 8.5 



Potash 20-0 



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



100.0 



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

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

 crop includes 224 Ibs. of nitrogen, equal to 272 Ibs. of ammonia, 

 and 672 Ibs. of mineral matter or ash constituents. 



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



Phosphoric acid 51i Ibs. 



Sulphuric acid 29 



Carbonic acid 121 



Silica 20 



Lime 201 



Mai;nc>i;i 57 



Potash 134* 



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



" 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 arc 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. Slraw. 



Water 15.0 16.0 



Nitrogenous substances, flesh-forming matter)* 11.1 4.0 



Nim-nitrofjenous substances 7'-.\:2 74.9 



Mineral matter, (ash) 1.7 5.1 



100.0 100.0 



* Containing nitrogen 1.78 .64= 



