Composition of Equivalent Crops of Wheat and Barley. 89 



45801b. total produce ; which will contain, approximately, 

 the following constituents : 



TABLE XX. NITROGEN AND ASH-CONSTITUENTS IN WHEAT AND 

 BARLEY. 



It will be observed that most of the above constituents 

 occur in nearly equal amount in either crop. The total 

 barley crop, however, would remove rather more lime, but 

 considerably less silica, than the wheat crop. But, looking 

 to the grain alone, the barley is seen to remove considerably 

 more silica, and rather more of each of the other con- 

 stituents than the wheat. Therefore, where the grain only 

 is sold, and the straw is returned to the land in due course 

 as manure, the eventual loss to the soil would be upon the 

 whole greater, especially in silica, by the growth of such a 

 crop of barley than of such a crop of wheat. In the 

 experiments under notice, however, both grain and straw 

 are always removed from the land. 



The exact quantities of manures applied on a given plot 

 will be specified where necessary. The mineral or ash con- 

 stituents were supplied in the following commercial forms : 

 Potash, as sulphate of potash ; soda, as sulphate of soda ; 

 magnesia, as sulphate of magnesia (Epsom salts) ; lime, 

 as sulphate, phosphate, and superphosphate ; phosphoric acid, 

 as bone-ash, mixed with sulphuric acid in quantity sufficient 

 to convert most of the insoluble earthy phosphate of lime 



