EFFECT OF NITROGENOUS MANURES 161 



will be seen that, large as is the amount of nitrogen applied 

 to Plot 9, the increased quantity on Plot 11-1 has its 

 effect in an increased crop. On Plot 9 the hay has averaged 



Without Nitrogen. 

 A 



With Nitrogen. 



Cwt. per Ac 

 SO 



Plots 



3&I2 



FIG. 21. Effect of the various Ash constituents with and without Nitrogen on the 

 produce of Hay per acre. Average over 47 years (1856-1902). 



Plots 3 and 12. Unmanured. 



Plot 4-1. Superphosphate. 

 Plot 8. Minerals without Potash. 

 Plot 7. Complete Mineral Manure. 



Plot 4-2. Super, and Amm.-salts = 86 Ib. N. 

 Plot 10. Minerals (without Potash) and 



Amm.-salts = 86 Ib. N. 

 Plot 9. Complete Mineral Manure and 



Amm.-salts = 86 Ib. N. 



54 cwt. over the whole period, on Plot 11-1 the crop is 

 increased to more than 66 cwt.* Comparing these results with 

 the 41 cwt. obtained from Plot 7 (minerals without nitrogen), 

 it will be seen how great is the effect of nitrogen in the produc- 



* The figures are taken from Table LVII. ; they differ very slightly from 

 those in the above diagram, which gives the figures up to 1902. 



L 



