74 



EXPERIMENTS UPON BARLEY 



wheat plot. The more limited root-range of the plant would 

 bring about a complete exhaustion of the available soil much 

 sooner with barley than with wheat, but there is evidence that 

 the decline in the yield of these barley plots is to some extent 



GRAIN 



Bushels 

 per Acre 



60 - 



50 



40 



30 



20 



10 



7-2 



mean of 

 4A,AA&C 



1852-1861 



1862-1871 



1872-1881 



1882-1891 



1892-1901 



1902-1911 



FIG. 10. Yield of Barley during successive 10-year periods (1852-1911). 



Plot 7-2. Farmyard Manure. Plots 4 A, AA, and C. Each receive Complete Minerals, 



+ N. as Amm.-salts, Nitrate Soda, or Rape Cake. Plot 1 O. Unmanured. 



due to a run of less favourable seasons. Both the continuously 

 dunged plot, which must be gaining fertility, and the plots 

 which receive heavy complete dressings of artificial manures 

 showed a similar decline in the average production from 1862 

 to 1902, though for the last ten years the yield on the latter 



