Microbial biomass and dehydrogenase activity in soils with varying clay contents during decomposition of crop residues

A laboratory incubation experiment for 85 days was undertaken to monitor the effect of clay contents in soils on periodical changes in soil microbial biomass carbon, nitrogen and dehydrogenase activities during decomposition of wheat and rice straws. Results have shown that incorporation of straws at 5 g kg⁻¹ soil significantly increased microbial biomass carbon, nitrogen contents and dehydrogenase activity in all the soils; and such increase was highest in soil with maximum clay content. Irrespective of clay content, increasing trend of the above parameters was observed up to 20 days and thereafter it declined gradually. It was clear that amount of clay played an important role to modify the biological activities during the decomposition of crop residues.