Winter cover crop legacy effects on litter decomposition act through litter quality and microbial community changes

1. In agriculture, winter cover crop (WCC) residues are incorporated into the soil to improve soil quality, as gradual litter decomposition can improve fertility. Decomposition rate is determined by litter quality, local soil abiotic and biotic properties. However, how these factors are interlinked and influenced by cropping history is unclear. 2. We grew WCC monocultures and mixtures in rotation with main crops Avena sativa and Cichorium endivia and tested how crop rotation influences WCC litter quality, abiotic and biotic soil conditions, and litter decomposition rates. To disentangle WCC litter quality effects from WCC soil legacy effects on decomposition, we tested how rotation history influences decomposition of standard substrates and explored the underlying mechanisms. 3. In a common environment (e.g. winter fallow plots), WCC decomposition rate constants (k) correlated negatively with litter C, lignin and, surprisingly, N content, due to strong positive correlations among thes...1. 在农业生产中，冬季覆盖作物（winter cover crop, WCC）残体常被翻埋入土以改善土壤质量，因其枯落物逐步分解可提升土壤肥力。枯落物分解速率由其自身品质、区域土壤非生物与生物属性共同决定。目前尚未明确这些因素间的相互关联机制，以及其受种植历史的调控规律。 2. 本研究设置冬季覆盖作物单作与混作体系，并与主栽作物燕麦（Avena sativa）和菊苣（Cichorium endivia）进行轮作，探究轮作对冬季覆盖作物枯落物品质、土壤非生物与生物条件，以及枯落物分解速率的影响。为厘清冬季覆盖作物枯落物品质效应与其土壤遗留效应对分解过程的独立作用，我们测试了轮作历史对标准底物分解的调控作用，并探索了其潜在作用机制。 3. 在统一控制环境（如冬季休耕样地）中，冬季覆盖作物的分解速率常数（k）与枯落物碳、木质素含量呈显著负相关；令人意外的是，其与氮含量同样呈负相关，这是由于各组分间存在较强的正相关关系。