Soil microorganism regulated aggregate stability and rill erosion resistance under different land uses

Abstract

How microbial communities respond to soil aggregation and rill erosion resistance has rarely been addressed. Such a knowledge gap hinders the practice of guiding sustainable soil management. Herein, the community composition of bacteria and fungi was evaluated by 16S rRNA gene sequencing. We measured critical shear stress (τc) and rill erodibility (kd) by self-made jet device. The effects of microorganism on soil aggregation and rill erosion resistance were quantitatively analyzed under different land uses.The results indicated that the forest soil supported the colonization and enrichment of Acidobacteria and Basidiomycota on account of the unique vegetation and higher soil organic carbon (SOC). The forest and shrubland contained higher macroaggregate and mean weight diameter (MWD) than those of cropland and bare land, while rill erodibility (kd) was the opposite. MWD and kd had a negative power function (y = 105.64x−0.69). The biotic factors explained 73.50% of the variation in rill erosion resistance and soil aggregation, indicating microorganism are more important in acting on rill erosion resistance.This study suggests that SOC had strong regulatory effects on the soil key groups of bacteria and fungi assemblages; furthermore, their interaction facilitated the formation of stable macroaggregates. The stable macroaggregate structure and vegetation cover make the erodibility of forest soil at a relatively low level. However, cropland are not conducive to stability of aggregates, which easily causes soil erosion. Improving soil SOC and maintaining the relative abundance of key groups of microorganism would be conducive to soil sustainable developing.