200 AMMONIFICATION 



soil in pots and after four months the ammonifying powers deter- 

 mined. In the second and third columns are given the results from 

 actual field soil receiving each year the designated quantity of 

 manure. 



Pot Field Experiment 



Treatment Experiment Fallow Cropped 



No manure 100 100 100 



5 tons of manure 122 147 129 



10 " " " 140 



15 " " " 152 188 183 



20 " " " 160 



25 " " " 180 



Crops grown on a soil decrease its ammonifying powers. In the 

 order of their decreasing ammonifying powers came fallow, potato, 

 corn, oats, and alfalfa. 



Influence of Soil and Climatic Conditions. Lipman points out 

 that the ammonia production in a soil is affected by (1) its mechani- 

 cal and chemical composition, (2) by fertilizer treatment, and (3) 

 by methods of tillage and cropping. He further states that the 

 mechanical composition of the soil determines the proportion of 

 aerobic and anaerobic organisms in a soil. If the latter predominate, 

 the production of ammonia is comparatively rapid. Yet Fischer 

 reports a more intense ammonification of dried blood in light than 

 in heavy soils, but under this case it is possible that the loss of 

 nitrogen from the sandy soil was sufficient to account for the 

 observed difference. C. B. Lipman has shown that the order within 

 various soils differs with the various ammonifying organisms. 

 Moreover, he and Waynick found the removal of California soil to 

 Kansas increased the ammonifying powers about one-third, but 

 removal to Maryland had little effect. Whereas Kansas soil re- 

 moved to California loses greatly in its ammonifying power, yet 

 Kansas soil transported to Maryland suffers little change. We must, 

 therefore, conclude that climate exerts a great influence on the 

 ammonifying powers of the soil. 



The quantity of ammonia in a soil varies from season to season 

 and from period to period. Green found that as regards the 

 ammonification of the organic manures flesh meal, horn meal, and 

 blood meal the bacterial activities rise from August to October, 

 with a tendency to fall or remain constant in November, rising to a 

 maximum in December. This was followed by a minimum in 

 February and a low maximum in April, and from April to July there 

 was a slight fall which probably continued to a summer minimum 

 commencing in August. 



Moisture. The influence of moisture on the ammonia formed in 

 the soil is very great. Lipman and Brown found ammonification 

 in a loam soil increased with increased water content even up to 

 35 per cent, of the^eight of the soil. However, later they and 



