of 



37 



ences. Tho plots under considoration, all of which received the same 

 amount of nitrogen in manure, are there given in tlie order of their 

 average annual increased yield of nitrogen in the crops over plot 5. 

 The first column shows the estimated average annual increased yield of 

 nitrogen per acre in the crops ; the second, the estimated annual loss 

 of nitrogen as nitric acid by drainage ; the tliird, the estimated pnnual 

 excess of nitrogen in the surt'ace soil over that on plot 5 with tho 

 mineral manure alone ; and the last column shows the relation which 

 that excess in tho soil bears to 100 increased yield of nitrogen in the 

 crops 



Tahlk X. 

 .Estimated Nitrojen j)er Aero per Annum, 



It is seen that tho increased yield of nitrogen in the crops also 

 varied exceedingly with the same amount supphed in manure, accord- 

 ing to the condition as to supply of mineral constituents. Plot 10, 

 with the ammonium salts alone, gives the smallest increased yield of 

 nitrogen in the crop ; and plots 7 and 9, with the most complete 

 mineral manure, each more than twice as much; the other plots 

 giving intermediate amounts. 



The order of the estimated loss of nitrogen by drainage is almost 

 the converse of that of the increased yield in the crops. Plot 10, 

 which gives the least increased yield in the crop, shows the greatest 



<c 



