[Effects of Different Fertilization Measures on Microbial Community and Enzyme Activities in Brown Soil]

The aim of this study was to explore the effects of different fertilization measures on nutrients and winter wheat yield in brown soil fields， analyze the characteristics of soil extracellular enzymes and microbial communities， and provide a theoretical basis for effectively improving soil fertility and winter wheat yield in brown soil fields. Based on seven consecutive years of positioning tests from 2017 to 2024， including five different fertilization measures， soil nutrient content， extracellular enzyme activity， and bacterial and fungal community structure and function were analyzed by using high-throughput sequencing technology and the ecological network method in a no fertilization treatment （CK）， conventional fertilization treatment （NPK）， optimized fertilization treatment （NPKM）， single organic fertilizer treatment （OM）， and conventional fertilization + straw direct return treatment （NPKS）. The results showed that：① Different fertilization measures （NPK， NPKM， NPKS， and OM） could improve soil fertility， wheat yield， and extracellular enzyme activity， among which the NPKS treatment had the most significant effect. ② Different fertilization measures changed the composition of the soil bacterial community， and the relative abundance of Proteobacteria and Bacteroidetes was increased， while the relative abundance of Acidobacteria was decreased. SOC， UE， and TP were important factors affecting the composition of bacterial communities. ③ The dominant phyla of soil fungi were Ascomycetes， Basidiomycetes， and Mortieromycetes. The relative abundance of Ascomycetes and Mortierella was increased. DHA， AP， and UE were important factors affecting the composition of the fungal community. ④ Different fertilization measures increased the complexity of the soil bacterial community network and decreased the complexity of the soil fungal community network. ⑤ FAPROTAX bacterial function prediction results showed that different fertilization measures improved soil carbon and nitrogen cycling-related functions. FUNGuild fungal function prediction showed that returning straw to field could inhibit the growth of soil pathogens， while applying organic fertilizer could promote the growth of saprophytic fungi. Different fertilization measures could improve soil fertility and extracellular enzyme activity， increase the abundance of beneficial bacteria， significantly change the structure and composition of the soil microbial community， and promote soil carbon and nitrogen cycling. Straw returning to field could inhibit the growth of soil pathogens. The effects of organic and inorganic combined application （NPKS and NPKM） were better than those of NPK and OM. Organic and inorganic combined application was conducive to improving soil quality， promoting carbon and nitrogen cycling， and increasing crop yield， so as to achieve sustainable development of dry farming.