Effect of combining straw‐derived materials and wood ash on alkaline soil carbon content and the microbial community

Abstract The return of organic materials to cultivated fields to improve soil quality and to sequester carbon are widely studied, but the effects of combining different types of organic material on soil microbial diversity and community structure are poorly understood, particularly in alkaline soils. An incubation experiment was performed to study the effects of incorporating two straw‐derived materials (fresh straw and semi‐decomposed straw) alone or in combination with wood ash. The organic carbon content of soil treated with straw‐derived materials was significantly higher than that of soil with no straw and wood addition, but there was no significant difference between the fresh straw and semi‐decomposed straw treatments. Microbial diversity was decreased by the addition of straw on day 7; however, the combination of fresh/semi‐decomposed straw with wood ash increased bacterial diversity on day 118, and the combination of semi‐decomposed straw with wood ash increased fungal diversity. Fresh straw combined with wood ash significantly increased the abundance of Ascomycota by 15.5% relative to that of soil treated with semi‐decomposed straw, and semi‐decomposed straw combined with wood ash increased the abundance of Basidiomycota by 40.5% relative to that of soil treated with fresh straw. Amendment with straw‐derived materials and wood ash shaped the bacterial community in alkaline soil by changing the soil organic carbon, dissolved organic carbon and pH, and the characteristics of straw‐derived materials and wood ash shaped the fungal community. Straw‐return modes that employ semi‐decomposed straw and wood ash addition can maintain organic carbon levels and improve the soil micro‐environment. Highlights Combining straw‐derived materials and wood ash affects alkaline soil carbon content and the microbial community. The effects of fresh and semi‐decomposed wheat straw on soil microorganisms and soil carbon content are reported for the first time. The combination of semi‐decomposed wheat straw and wood ash enhanced soil fungal diversity and Basidiomycota abundance. Semi‐decomposed wheat straw and wood ash can maintain organic carbon levels and improve the soil micro‐environment.