Cover crops in arable lands increase functional complementarity and redundancy of bacterial communities

1. Reducing the deleterious effects of intensive tillage and fertilisation on ecosystem integrity and human health is challenging for sustainable agriculture. The use of cover crops has been advocated as a suitable technique for this purpose, but scientific evidence to support this has been scarce. 2. After four years and a complete rotation; including wheat, maize and green pea as main crops in a ploughing system, we investigated the respective and combined effects of cover crops and nitrogen fertilisation on soil chemical and biological properties using a controlled experiment combining soil chemical analyses, high-throughput sequencing and community level physiological profiles. 3. Cover crops impeded the soil carbon and nitrogen depletion induced by intensive tillage, not only in the topsoil but also within deeper soil horizons, where more specialized bacterial communities established. 4. Cover crops induced a significant shift in soil bacterial community diversity and composition, which was associated with changes in soil chemical features and bacterial metabolic activities along the entire soil profile. 5. Cover crops enhanced soil resilience to nitrogen fertilisation by increasing functional redundancy and complementarity within soil bacterial communities and across soil horizons. 6. Synthesis and applications. In the ploughing systems commonly used for intensive agriculture in Western Europe, the use of cover crops fosters a high functional diversity among soil bacteria and thus can help to achieve a more sustainable agriculture by reducing nitrogen fertilization while maintaining yields.

1. 对于可持续农业而言，降低集约化耕作与施肥对生态系统完整性及人类健康造成的有害影响，是一项颇具挑战性的课题。覆盖作物（Cover Crops）的应用被提议作为实现该目标的可行手段，但相关支撑性科学证据却较为匮乏。2. 本研究在耕作体系中以小麦、玉米与豌豆作为主栽作物开展了为期四年的完整轮作试验，通过结合土壤化学分析、高通量测序（High-Throughput Sequencing）与群落水平生理剖面的受控实验，探究了覆盖作物与氮肥施用各自及联合作用对土壤化学与生物学特性的影响。3. 覆盖作物可抑制集约化耕作诱导的土壤碳氮耗竭，该效应不仅存在于表层土壤，在深层土壤土层中亦有体现——此处会形成更为特化的细菌群落。4. 覆盖作物会显著改变土壤细菌群落的多样性与组成，该变化与整个土壤剖面的土壤化学特征及细菌代谢活性的改变密切相关。5. 覆盖作物通过提升土壤细菌群落内部及不同土层间的功能冗余性与功能互补性，增强了土壤对氮肥施用的恢复力。6. 研究总结与实践应用：在西欧集约化农业普遍采用的耕作体系中，覆盖作物的应用可促进土壤细菌群落具备较高的功能多样性，因此能够在维持作物产量的前提下，通过降低氮肥施用量，助力实现更可持续的农业生产。