Dynamic Changes Of Soil Enzyme Activities And Soil Microbial Communities In Microorganism Inoculants And Chemical Fertilizers In Different Proportions After Straw Returning Soil

This study investigated the effect of different treatments on the dynamic change of soil activity, soil microbial community, soil electrical conductivity (EC), soil pH, soil density and soil physical and chemical properties in wheat and corn growth period. It is helpful to explain the process and mechanism of straw decomposition, stalk soil quality assessment and soil microbial communities well and offer important scientific value. We conducted a field experiment that included six treatments: 1) straw returning (control, CK), 2) straw returning and fertilizes (SF), fertilizes includes nitrogenous fertilizer and phosphate fertilizer, 3) straw returning, fertilizes and phosphate fertilizer (SFN), 4) straw returning, fertilizes, phosphate fertilizer and enzymes (SFNE), 5) straw returning, fertilizes, phosphate fertilizer and decomposing microbial inoculums (SFND), 6) straw returning, fertilizes, phosphate fertilizer , enzymes and decomposing microbial inoculums (SFNED). The research results are as follows:(1) According to the mean value, the soil sucrose enzyme activities of different treatments decreased in the order SFNED>SFNE>SFND>SFN>SF>CK; the soil alkaline phosphatase activities of different treatments decreased in the order SFNED>SF>SFND >SFN>CK>SFNE; the soil urease activities of different treatments decreased in the order SFNE>SFN>SFNED>SFND>SF>CK; the soil polyphenol oxidase activities of different treatments decreased in the order CK>SFNE>SF>SFND>SFNED>SFN. The significantly positive correlations were found between the activities of SFNED and CK.(2) The same trend of soil pH in different treatments and slightly rising in neutral and alkaline range. The mean value of soil pH is significant difference between the treatments of SFN, SF and CK.(3) The same trend of soil EC in different treatments. It showed a slightly downward trend and it characterized volatile early and late tended to be stable . The mean value of soil EC is significant difference between the treatments of SFND, SFNE, SFNED and CK.(4) Compared with the CK treatment, the soil bulk density of microbial agents and fertilizer application in different treatments decreased by 13.21% ~ 20.25% and the difference was very significant. The soil bulk density of different treatments after the test in the order SFNEDSFND>SFNE >SFN>SF>CK. Compared with the CK treatment, the wheat production of microbial agents and fertilizer application in different treatments increased by 17%～57%. The corn production of different treatments in the order SFND>SFNED>SFNE>SFN>SF>CK. Compared with the CK treatment, the corn production of microbial agents and fertilizer application in different treatments increased by 16%～60%.(7) The AWCD of soil microbial communities in the four treatments of CK, SF, SFN, SFND was distinctly different. The maximum growth slope of AWCD was SFND treatment and significantly positive between SFND and CK (ρ<0. 01). But they were un-remarkably between SF, SFN and CK. It explained that microbial agents were larger than chemical fertilizer on AWCD of soil microbial communities. By the principal component analysis, the variation of typical variable values was the (dispersion) minimum in treatment SFND, but the treatments of SF and SFN were contrary. This showed that the treatment SFND was the best. Compared to other treatments, treatment SFND made microbial species more abundant, the number of species more increase, individuals up and distributed more evenly.