Changes in Soil Fungal Community on SOC and POM Accumulation under Different Straw Return Modes in Dryland Farming

ABSTRACT We conducted a 2.5-year field experiment to test the effects of straw incorporated evenly into the soil (EIS) on soil fungal community, SOC chemical composition, and particulate organic matter fractions via comparing with no straw returning (CK), straw mulching (SM), straw plowed into the soil (SP), and identified the linkages between soil fungal community as well as organic C accumulation and POM formation. Our results showed that EIS treatment significantly increased the concentrations of SOC and the proportion of carbohydrate C, di-O-alkyl C, and O-alkyl C in SOC structure, increased the mass proportion and OC contents of MA(c)POM and mM-POM in the upper 40 cm of soil. Meanwhile, EIS treatment increased the relative abundance of Ascomycota, Zygomycota, Chytridiomycota , and Dothideomycetes in 0–20 cm depths, and also had the highest relative abundance of Glomeromycetes and Dothideomycetes in the 20–40 cm soil. Also, our study suggests that straw return enhanced the relative abundances of fungi involved in the carbon cycle and sequestration, including Zygomycota, Chytridiomycota, and Glomeromycota, and Ascomycota. The shifts in fungal community structure can accelerate organic C accumulation and the formation of soil particulate organic matter, especially in EIS treatment.