ENERGY AND NITROGEN TRANSFORMATION 519 



over a longer period of time than that of an organic material con- 

 taining more nitrogen, like clover residues. The more rapid decom- 

 position of the latter is accompanied by a more rapid increase in the 

 number of microorganisms concerned in the process followed by a 

 more rapid drop. The removal of nitrate from the soil solution will, 

 therefore, not be as prolonged in the case of clover as in the case of 

 timothy residues; this tends to explain the slight depression of the 

 nitrate content of the soil as a result of addition of clover or other 

 leguminous materials than that following the addition of timothy 

 or other plant residues low in nitrogen. 23 



23 Wilson, B. D., and Wilson, J. K. An explanation for the relative effects 

 of timothy and clover residues in the soil on nitrate depression. N. Y. (Cornell) 

 Agr. Exp. Sta., Mem. 95. 1925. 



