Short-term effect of biogas residue on some soil enzymes activities under maize and clover growth in a semiarid ecosystem

Abstract

The increases in anaerobically digested organic wastes in the world created a greater attention to evaluate the impact of the residue on soil properties. The purpose of this experiment was to evaluate anaerobically digested cattle manure on some soil chemical and biological properties under maize and clover production. Biogas residue was applied as 20, 40 and 60 t ha-1 (BGR20, BGR40 and BGR60) to the plots with a control (including only chemical fertilizers). Soil samples were taken from 0-15 and 15-30 cm depths at the end of growing season of maize and clover (October). Soil organic carbon (SOC) slightly increased with biogas residue while the increase was greater in microbial biomass carbon (MBC). However, microbial biomass nitrogen (MBN) was constant through the treatments and only significant difference occurred between the plants as greater in clover plots. Dehydrogenase enzyme activity was similar in maize plots and slightly increased in clover BGR40 compared to control. β-glucosidase enzyme activity significantly increased with the amendment of biogas residue compared to control, but there is no significant change between the rates of biogas residue. Alkaline phosphatase enzyme responded greatly to the doses of biogas residue than the others. The ratio of MBC/SOC enhanced with biogas residue however, the contrasting effect for dehydrogenase enzyme activity per microbial biomass was observed. These findings indicate that the response of soil enzymes on biogas waste can vary depending on the processing of organic waste. The activities of soil enzymes are sensitive to the characteristic of organic materials.