Earthworms mitigate the straw-induced microbial resource limitation and increase microbial carbon use efficiency in the no-tillage system

Abstract

No-tillage with straw return is an effective strategy for improving soil quality and fostering earthworm community. Straw return could increase soil microbial resource limitations, which strongly change the processes of microbial metabolism and subsequently nutrient cycling in agroecosystems. However, the soil microbial resource limitations in response to increased earthworm community remain unclear. A microcosm experiment was conducted to quantify how earthworms regulate the effect of straw addition on microbial resource limitations and subsequent impact on microbial carbon use efficiency (CUE). Results showed that straw return enhanced microbial nitrogen (N) limitation, but this enhancement was mitigated by earthworms, primarily due to increased nutrients availability. Earthworms with straw addition significantly enhanced microbial CUE, primarily attributed to the increased nutrients availability and reduced microbial resource limitations. Overall, our results revealed that earthworms decreased straw-induced microbial N limitation and increased microbial CUE, emphasizing the importance of earthworms in balancing soil microbial resource limitations and C sequestration in the no-tillage agricultural system.