EFFECTS OF AMMONIUM-SALTS 



53 



nitrogen are used, the accumulation of nitrogen is far less] than 

 the difference between the nitrogen applied and that removed 

 would indicate. 



Total Produce 

 per Acre 



6000 I b. 



3OOO 



IOOO 



Plot 5 



Minerals 

 only. 



7 



Minerals 



+86lb.N. 



Spring. 



15 



Minerals 

 +86lb.N. 



18 



17 



Minerals 



+86lb.N. 86lb.N. 



Autumn. for Previous after Minerals only 



Crop. in Previous Year. 



'Straw per Acre, Ib. 



I Grain per Acre, Ib. 



FIG. 8. Comparative Effects on Wheat of Ammonium-salts appb'ed at different times. 

 Averages for 51 years (1852-1902). Plots 7 and 15, 25 years only (1878-1902). 



Periodical determinations of nitrogen in soil and crop 

 enable us to draw up an estimate of the nitrogen per acre 

 supplied in the manure and recovered in the crop over a fifty- 



