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.
The differences in C isotope ratio of C 3 and C 4 plant species have been used to determine relative contributions of carbon (C) sources to total CO 2 efflux. The objective of this study was to estimate the contribution of soil organic C and C 3 sugar to total CO 2 of corn and wheat monocultures during a short-term incubation. Control soils and soils amended with sugar were incubated at 25°C for 48 hours and total CO 2 concentration and δ 13 C values of evolved CO 2 were measured. The proportional contribution of C sources on CO 2 efflux was determined by using isotopic composition of soil organic C and C 3 sugar. δ 13 C values of soils are highly affected by the type of vegetation and the soil management. The C 3 sugar addition in soils double the CO 2 efflux in the corn soil, but it did not affect CO 2 efflux in the wheat soil. This indicated a larger turnover of microbial biomass in the corn soil. The greatest significant (P < 0.05) difference in δ 13 C values between the control and sugar added soils occurred at 12 hours in the corn soil (11.2‰) and at 24 hours in the wheat soil (9.4‰). The estimated relative contribution of sugar to CO 2 efflux was stronger at 12 hours incubation in the corn soil.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.