74 



EXPERIMENTS UPON BAKLEY 



limited root-range of the plant would luring 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 due to a run of les& 



GRAIN 



Bushels 

 per Acre 



562-187I 



ieS2-l9C 



Fig. 10.— Yield of Barley during successive 10-year periods (1852-1901). 



Plot 7-J.— Farmyard Manure. Plots 4 A, N, and C— Each receive Complete Minerals, 



+ X. as .\mm,-salts. Nitrate Soda, or Rape Cake. Plot 1-0.— Unmanured. 



ftivourable seasons. Both the continuously dunged plot, which 

 must be gaining fertility, and the plots which receive heavy com- 

 plete dressings of artificial manures show a similar decline in the 

 average production for the last four decades, as may be seen 



