280 Proceedings of Indiana Academy of Science 



Plots 13 and 14 (continuous wheat, unlimed and limed respectively) 

 were lowest in average nitrate content of all the wheat plots. 



Plot 15, continuous corn, was lowest of all the corn plots with only 

 18.61 parts of nitrates per million. 



From the above facts the following conclusions can be drawn: 



(1) It seems that the following rotations ai-e effective in producing 

 high nitrifying power of the soil, in the order named: (1) Corn, wheat, 

 clover and timothy; (2) corn, oats, wheat, clover and timothy; (3) corn 

 and wheat; and (4) corn, oats and wheat. 



(2) Soil continuously cropped to either wheat or corn shows a 

 lower nitrifying power than soil cropped to any of the above rotations. 



(3) The present crop has more influence on nitrification than previ- 

 ous ci'ops. 



