Response of Soil Microbial Biomass Carbon, Nitrogen and Enzyme Activity to Sophora Davidii Skeels and Pennisetum Sinese Roxb Intercropping Systems

Abstract

To understand the response mechanism of soil microbial biomass carbon content, soil microbial biomass nitrogen content and soil enzyme activities to intercropping pattern, an experiment consisting of three cropping patterns: Sophora davidii Skeels monocropping pattern, Pennisetum sinese Roxb monocropping pattern and S. davidii and P. sinese intercropping pattern had established in the southern region of Guizhou Province, China. The results showed that soil microbial biomass carbon content, microbial biomass nitrogen content and enzyme activities were gradually reduced with the depth (0-30 cm) of the soil layer increased under the three cropping patterns. The microbial biomass carbon and nitrogen content of S. davidii and P. sinese intercropping pattern were significantly higher than those of S. davidii monocropping and P. sinese monocropping pattern in 0-20 cm soil layer (P <0.05). Five soil enzyme activities were ranked: P. sinese monocropping > S. davidii and P. sinese intercropping > S. davidii monocropping in most soil layers. The soil nutrient contents (soil organic matter, total nitrogen, total phosphorus, and total potassium) and soil microbial biomass content (microbial biomass carbon and nitrogen) were highly significant positive correlation (P <0.01), while five soil enzyme activities had a significant positive correlation with each other (P <0.05). However, there was no significant correlation between soil microbial biomass content and soil enzyme activities. Additionally, there was non-significant correlation between the activiies of nitric oxide synthetase, the activiies of β-N-acetylglucosidase and the activiies of leucine aminopeptidase (P> 0.05), but the activiies of β-N-acetylglucosidase, the activiies of soil nitrogenase, the activiies of soil Leucine aminopeptidase and the activiies of soil glutamine synthetase were showed a significant (P <0.05) or very significant positive correlation (P <0.01). In summary, the intercropping pattern of S. davidii and P. sinese has a significant effect on soil quality improvement in shallow soil (0-20cm), and the microbial biomass carbon, soil microbial biomass nitrogen and soil enzymes can be used as an important index for evaluating the changes of soil quality.