EXPERIMENTS ON CLOVER. 139 



I 



" The ash of wheat contains, in 100 parts : 

 i Grain. 



Phosphoric acid 50.0 



Sulphuric acid 0.5 



Carbonic acid 



Silica 2.5 



Lime 3.5 



Magnesia 11.5 



PoUsh 30.0 



Soda, chloride of sodium, oxide of ii"on, sand, etc 2.0 



Total 100.0 



" The mean produce of wheat, per acre, may he 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 lbs. of mineral food, (in round numbers). 



Total 175 lbs. 



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

 position of these 175 lbs. is as follows: 



Total. 



Phosphoric acid 12.5 lbs. 7.5 lbs. 20.0 lbs. 



Sulphuric acid 0.1 " | 4.0 " 4.1 ' 



Carbonic acid. 



Silica 0.0 " 100.5 " 101.1 



Lime 0.9 " \ 8.2 " 9.1 



Magnesia 2.9 " 3.0 '• .5.9 



Potash T.5 " I 19.5 " 27.0 



Soda, chloride of sodium, oxide of iron, sand, etc.! 0.5 " 7.3 " 7.8 



175. lbs: 



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

 average crop of wheat, 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, there- 

 fore, need not trouble ns in any way, especially as there is not a 

 single instance on record, proving that silica, even in a soluble 

 condition, has ever been applied to land, with the slightest advan- 

 tage to corn, or grass-crops, which are rich in silica, and which, for 

 this reason, may be assumed to be pai'tieularly grateful for it in a 

 soluble state. Silica, indeed, if at all capable of producing a bene- 

 ficial effect, ought to be useful to these crops, either by strengthen- 

 Uig the straw, or stems of graminaceous plants, or otherwise hene- 

 Iting them; but, after deducting the amount of silica from the 



