Comparison of methods of assaying urease activity in soils

Abstract

Analyses of 16 soils selected to obtain a wide range in properties showed that the results obtained by a buffer method of assaying urease activity were markedly higher than those obtained by a non-buffer method. Both methods gave reproducible results, but the non-buffer method was the more precise, and studies reported showed that it provides a much better index than the buffer method of the ability of soils to hydrolyze urea under natural conditions. The buffer method detects urease activity that does not occur when soils are treated with urea in the absence of buffer. This is a disadvantage if the purpose of the assay is to obtain an index of the ability of soils to hydrolyze fertilizer urea, but is an advantage if the purpose is to detect urease in soils or soil fractions. Use of toluene to inhibit microbial activity in assay of urease activity by the non-buffer method described did not significantly affect the results obtained by this method, but it is decreased the precision of the method.