[Effects of Carbon-based Fertilizer on Soil Physical and Chemical Properties, Enzyme Activities and Microbial Communities in Maize Fields in Arid Regions].

This study investigates the impact of biochar-based fertilizer on soil environmental factors and microbial communities to address how biochar-based fertilizer can improve soil conditions in arid regions and promote sustainable agricultural development. To achieve these goals, maize "Xianyu 335" was selected as the test variety and a random block design was adopted to set up five treatments： CK （conventional fertilizer at 450 kg·hm）, T1 （biochar-based fertilizer at 1 125 kg·hm）, T2 （biochar-based fertilizer at 1 013 kg·hm）, T3 （biochar-based fertilizer at 900 kg·hm）, and T4 （biochar-based fertilizer at 788 kg·hm）. Soil samples were collected from mature corn fields and analyzed for changes in soil physicochemical properties, soil enzyme activities, and microbial diversity under the different biochar-based fertilizer treatments. The results showed that： ① Compared with that using chemical fertilizer alone, the application of biochar-based fertilizer significantly reduced the soil bulk density, increased the soil porosity and field water capacity, and increased the soil nutrients and enzyme activities. The contents of organic carbon, total nitrogen, and total phosphorus in the T1 and T2 treatments were significantly increased by 13.68%-32.63%, 25.00%-26.79%, and 35.00%-47.50%, respectively. The activities of urease, sucrase, and alkaline phosphatase were significantly increased by 49.04%-91.35%, 48.88%-58.71%, and 20.69%-31.03%, respectively. ② The T3 and T4 treatments reduced the Chao1, Shannon, Simpson, Faith_pd, and Pielou_e indices of microorganisms. The dominant bacteria of each treatment were Proteobacteria, Actinobacteria, and Acidobacteria, with relative abundances ranging from 71.50%-86.66%. The T1 and T2 treatments significantly increased the relative abundance of Proteobacteria and Actinomycetes and decreased the relative abundance of Acidobacteria. No significant difference was observed in the relative abundance of amino acid metabolism, carbohydrate metabolism, energy metabolism, genetic information processing, and metabolic function, all of which were between 18.12% and 21.34%. ③ Correlation analysis showed that in addition to soil bulk density, soil physical properties, soil nutrients, and soil enzymes were significantly positively correlated with each other, and significant differences were present in the relationship between different dominant bacteria and soil environmental factors. The six functional pathways of microorganisms were significantly positively correlated with soil nutrients. PLS-SEM analysis showed that biochar-based fertilizer directly or indirectly affected the microbial community by regulating soil physical properties, soil nutrients, and soil enzymes, and soil nutrients were the main driving parameters of soil microbial community succession. Finally, PCA analysis showed that the comprehensive fertility of soil was T2>T1>T3>CK>T4. Overall, biochar-based fertilizer improved the physical, chemical, and biological properties of soil in arid regions, thereby enhancing soil fertility. A biochar-based fertilizer application rate of 1 013-1 125 kg·hm is recommended for promoting corn cultivation in arid areas.