462 BOARD OF AGRICULTURE. 



The ash of wheat contains in 100 parts : 



Grain. Straw. 



Phosphoric acid 50.0 5.0 



Sulphuric acid 0.5 2.7 



Carbonic acid 0.0 0.0 



Silica 2.5 67.0 



Lime 3.5 5.5 



Magnesia 11.5 2.0 



Potash 30.0 13.0 



Soda, chloride of sodium, oxide of iron, sand, (fee. . . 2.0 4.8 



100.0 100.0 



V 



The mean produce of wheat per acre may be estimated at 25 

 bushels, which, at 60 lbs. per bushel, gives 1,500 lbs. ; and as the 

 weight of the straw is generally twice that of the grain, its pro- 

 duce will be 3,000 lbs. According, therefore, to the preceding 

 data, there will be carried away from the soil : 



In 1,500 lbs of the grain 25 lbs. of mineral food (in round numbers) 



In 3,000 lbs. of the straw 150 " " " " 



Total 175 lbs. 



On the average of the analyses, it will be found that the com- 

 position of these 1Y5 lbs. is as follows : 



In the grain. In the straw. Total. 



Phosphoric acid 12.5 lbs 7.5 lbs 20.0 lbs. 



Sulphuric acid 0.1 " 4.0 " 4.1 " 



Carbonic acid 0.0" 0.0" 0.0" 



Silica 0.6 " 100.5 " 101.1 " 



Lime 0.9 " 8.2 " 9.1 " 



Magnesia 2.9 " 3.0 " 5.9 " 



Potash 7.5 " 19.5 " 27.0 " 



Soda, chloride of sodium, oxide ) " " >-■><« 7 8" 



of iron, sand, itc 3 



25 lbs. 150 lbs. 175 lbs. 



The total quantity of ash constituents carried off the land in an 

 average crop of wlieat thus amounts to only 175 lbs. per acre, 

 whilst a good crop of clover removes as much as 672 lbs. 



Nearly two-thirds of the total amount of mineral in the grain 

 and straw of one acre of wheat consists of silica, of which there 

 is an ample supply in almost every soil. The restoration of silica, 

 therefore, need not trouble us in any way, especially as there is 

 not a single instance on record proving that silica, even in a solu- 

 ble condition, has ever been applied to land with the slightest 

 advantage to corn or grass crops, which are rich in silica, and 

 which, for this reason, may be assumed to be particularly grateful 



