Total Produce 

 per acre. 



70001b. 



6000 



5000 



4000 



3000 



2000 



1000 



Plots 3 4 



Grain per Acre, lb. HHi Straw per Acre, lb. 



Fig. 39. Diagram showing effect of increasing amounts of nitrogenous 

 manures on the yield of wheat. Broadbalk field, Rothamsted. 

 (Average 61 years, 1852-1912.) 

 Plots 3 and 4. Unmanured. 



Plot 5. Potash and phosphates but no nitrogenous manure. 

 6. Potash and phosphates and sulphate of ammonia containing 



43 lbs. N per acre. 

 7. Potash and phosphates and sulphate of ammonia containing 



86 lbs. N per acre. 

 8. Potash and phosphates and sulphate of ammonia containing 



129 lbs. N per acre. 

 The columns represent total produce per acre, but the figures in the 

 dia-nond spaces give bushels of grain and cwts. of straw per acre 



