The Decomposability of Some Plant Residues and Their Susbsequent Influence on Soil Microbial Respiration and Biomass, and Enzyme Activity

Soil microbial activity and biochemical processes are often limited by carbon availability in arid- and semi-arid regions, probably due to the low organic matter content. Consequently, return of plant residues to soil is a convenient and effortless practice for increasing microbial activities and biochemical reactions. The primary objective of this study was to evaluate the effect of various plant residues on soil microbial respiration and biomass, and enzymatic activities as well. The experiment consisted of a completely randomized design (CRD) with three replications under laboratory conditions. Experimental treatments consisted of seven plant residues including wheat, alfalfa, corn, rice, almond, walnut and grape, common in agro-ecosystems of Chaharmahal va Bakhtiari province, with a control soil without plant residue addition. Results show that the added plant residues brought about a significant increase in microbial activity (soil respiration) and biomass with concurrent increases in enzyme activities in the studied soil. The results of the current study indicate that enzyme activities would alter with changes in substrate quality during the course of plant residue decomposition. However, the extent to which, soil microbial activity and biomass, and enzyme activities fluctuate depended largely upon the type and quality of plant residues used, and the stage of residue decomposition.