THE OAT CROP. 



159 



These results show us that the different parts of the 

 plant require not only different proportions of mineral 

 matter to carry on their growth, but also different quali- 

 ties, which materially affect their relative feeding values. 

 Thus, in the grain we find phosphoric acid and potash the 

 principal constituents; in the husk and chaff these exist 

 in but small proportions, while the silica appears in excess ; 

 again in the straw we find the proportion of silica reduced, 

 and the alkalies (potash and soda) and sulphuric acid oc- 

 cupying its place. The absence of sulphuric acid in the 

 grain, and its presence in such large proportions in the 

 other parts of the plant, is also worthy of notice, as exem- 

 plifying the varied food requirements of the plant at dif- 

 ferent stages of its growth. Messrs. Way and Ogston 1 

 estimate the quantity of mineral matter removed from the 

 soil by a fair crop of oats (48 bushels) to be as follows : 



48 bushels of oats, at 42 Ibs. per bushel, contain 60^ Ibs. of ash. ) Ibs. 



The straw and chaff will weigh 3024 Ibs. and contain 138 Ibs. of ash. i ~~~ 199 



This quantity of ash (mineral matter) contains the dif- 

 ferent constituents in the proportions given : - 



Roy. Agri, Soc. Jour., vol. vii. p. 645. 



