158 Kooit I'oi; Plants. 



iiK'ul)alc'(l ill llic l;il)()i:il()r\ loi- a I'cw days, escaping 

 aiinnoiiia nia\- he (Ictcctcd, and I'roiii this it is a natural 

 conclusion that wiicii large (juantitics of oi-ganic matter 

 are placed in the soil under natural conditions, some 

 ammonia will he lost hy volatilization, especially when 

 the tem])erature and nu)isture conditions are favorable. 

 This then, together with the evolution of gaseous nitro- 

 gen, would in ])art at least exi)hnn the heavy loss of 

 nitrogen where manure was used at the rate of IG tons 

 per acre. 



A discussion of this subject would not 1)e completed 

 without a ])rief reference to the effect of cultivation on 

 nitrogen losses. 



Shutt -■ for example has shown that wlu'ii the prairie 

 soils of Saskatchewan were left undisturbed the loss of 

 nitrogen was slight, but as soon as cultivation was com- 

 menced losses set in. 



Russell (4) refers further to losses of nitrogen 

 as follows : 



One of tlie Rroadliallv wheat plots receives aimnally 14 tons of farm- 

 yard manure per ac-re containing 200 pounds of Nitrogen. Only a little 

 drainage can be detected and there is no reason to suppose that any 

 considerable leaching out of Nitrates occurs, but the loss of Nitrogen 

 is enormous amounting to neai-ly 70 per cent, of the added quantity. 



The condition for this decomposition appears to be copious aeration, 

 such as is ])roduced by cultivation and the presence of large quantities 

 of easily decomitosable organic matter. Now these are ])recisely the 

 conditions of intensive farming in old countries and of pioneer farming 

 in new lands, and the result is that the reserves of soil and manurial 

 Nitrogen are evei-ywliere being de])leted at an aiijialling rate. 



Russell refers to the recuperative actions that are 

 going on, but says: " One of the most pressing prob- 

 lems at the present time is to learn how to suppress this 

 gaseous decomposition and to direct the processes 

 wholly into the nitrate channels." 



In a pa])er on the nitrate content of cultivated and 

 uncultivated soils, Blair and McLean (1 ), have called at- 

 tention to the loss of nitrogen from cultivated soils and 

 also to the low recovery- from nitrogen applied as 



^ Cited bv Russell (4). 



