This review explores ways that cover crops alter soil environmental conditions that can be used to decrease seed survival, maintain weed seed dormancy, and reduce germination cues, thus reducing above-ground weed pressures. Cover crops are grown between cash crops in rotation, and their residues persist into subsequent crops, impacting weed seeds both during and after cover crops’ growth. Compared to no cover crop, cover crops may reduce weed seedling recruitment and density via: i) reducing soil temperature and fluctuations thereof; ii) reducing light availability and altering light quality; and iii) trapping nitrogen in the cover crop, thus making it less soil-available to weeds. In addition, cover crops may provide habitat for above- and below-ground fauna, resulting in increased weed seed predation. The allelopathic nature of some cover crops can also suppress weeds. However, not all effects of cover crops discourage weeds, such as potentially increasing soil oxygen. Furthermore, cover crops can reduce soil moisture while actively growing but conserve soil moisture after termination, resulting in time-dependent effects. Similarly, decaying legume cover crops can release nitrogen into the soil, potentially aiding weeds. The multiplicity of cover crop species and mixtures, differing responses between weed species, environmental conditions, and other factors hampers uniform recommendations and complicates management for producers. But, cover crops that are managed to maximize biomass, do not increase soil nitrogen, and are terminated at or after cash crop planting will have the greatest potential to attenuate the weed seed bank. There are still many questions to be answered, such as if targeting management efforts at the weed seed bank level is agronomically worthwhile. Future research on cover crops and weed management should include measurements of soil seed banks, including dormancy status, predation levels, and germination.Highlights - Cover crops alter the weed seed bank environment, influencing survival, dormancy, and germination. - Weed seed germination may be reduced by decreased temperature and fluctuations thereof, light, and soil nitrogen. - Weed seed germination may be increased by greater soil moisture, soil nitrogen, and oxygen. - Management should maximize cover crop biomass, decrease soil nitrogen, and delay termination for the greatest potential. - Future research should include measurements of weed seed banks, including dormancy status, predation, and germination.

中文翻译：

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覆盖作物作为杂草种子库管理工具：土壤向下审查

本综述探讨了覆盖作物改变土壤环境条件的方法，这些方法可用于降低种子存活率、维持杂草种子休眠和减少发芽线索，从而降低地上杂草压力。覆盖作物在经济作物之间轮作种植，其残留物会持续存在于随后的作物中，影响覆盖作物生长期间和之后的杂草种子。与无覆盖作物相比，覆盖作物可通过以下方式减少杂草幼苗补充和密度： i) 降低土壤温度及其波动；ii) 降低光照可用性并改变光照质量；iii) 将氮捕获在覆盖作物中，从而减少杂草可利用的土壤。此外，覆盖作物可能为地上和地下动物群提供栖息地，从而增加了对杂草种子的捕食。一些覆盖作物的化感作用也可以抑制杂草。然而，并非覆盖作物的所有影响都会阻止杂草，例如可能增加土壤氧气。此外，覆盖作物可以在积极生长的同时减少土壤水分，但在终止后保持土壤水分，从而产生时间依赖性效应。同样，腐烂的豆类覆盖作物可以将氮释放到土壤中，可能有助于杂草。覆盖作物种类和混合物的多样性、杂草种类、环境条件和其他因素之间的不同反应阻碍了统一的建议，并使生产者的管理复杂化。但是，能够最大限度地提高生物量、不增加土壤氮并在经济作物种植时或之后终止的覆盖作物将最有可能减少杂草种子库。仍有许多问题需要回答，例如在杂草种子库层面的目标管理工作在农艺学上是否值得。未来对覆盖作物和杂草管理的研究应包括土壤种子库的测量，包括休眠状态、捕食水平和发芽。亮点 - 覆盖作物改变杂草种子库环境，影响生存、休眠和发芽。- 降低温度及其波动、光照和土壤氮可能会减少杂草种子的发芽。- 更多的土壤水分、土壤氮和氧可能会增加杂草种子的发芽率。- 管理应最大化覆盖作物生物量，减少土壤氮，并延迟终止以发挥最大潜力。- 未来的研究应包括杂草种子库的测量，包括休眠状态、捕食、