Cover crops have been shown to be important integrated weed management tools. In addition to directly competing with weeds, cover crops can provide weed suppressive effects following incorporation through release of allelopathic compounds and/or changes to nutrient availability. Incorporation of a cover crop mixture may provide a synergistic or antagonistic effect on weed suppression by further altering nutrient dynamics. To investigate this phenomenon, we evaluated the suppressive effects following incorporation of annual ryegrass, buckwheat, brown mustard, and phacelia sown with and without field pea on germination and growth of several pernicious weed species. Further, we used the additive partitioning model to determine if pea synergistically improved biomass production and weed suppression of cover crops. Our results demonstrate that following incorporation, cover crop residues suppress weed germination and weed biomass production. According to the additive partitioning model, the addition of pea had an antagonistic effect on buckwheat and brown mustard biomass production and decreased buckwheat weed suppression by 8%. In contrast, the addition of field pea greatly enhanced biomass production of phacelia at a reduced seeding rate suggesting a positive biodiversity effect. Limited evidence was found for changes to nutrient availability following cover crop incorporation, however, a dose-dependent effect of cover crop residue on weed suppression suggests allelopathy and/or nutrient availability may have a role on weed seed germination success. Together, our results support the use of incorporated cover crop residues as an integrated weed management tool.

中文翻译：

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掺入覆盖作物残留物抑制杂草种子发芽

覆盖作物已被证明是重要的综合杂草管理工具。除了与杂草直接竞争之外，覆盖作物还可以通过释放化感化合物和/或改变养分利用率来提供杂草抑制作用。掺入覆盖作物混合物可以通过进一步改变养分动态来提供对杂草抑制的协同或拮抗作用。为了研究这一现象，我们评估了掺入一年生黑麦草、荞麦、褐芥菜和豌豆播种后对几种有害杂草的发芽和生长的抑制作用。此外，我们使用加性分配模型来确定豌豆是否可以协同提高覆盖作物的生物量产量和杂草抑制。我们的结果表明，掺入后，覆盖作物残留物会抑制杂草发芽和杂草生物量的产生。根据加性分配模型，豌豆的添加对荞麦和褐芥菜生物量生产具有拮抗作用，并使荞麦杂草抑制率降低8%。相比之下，豌豆的添加极大地提高了豌豆的生物量产量，同时降低了播种率，这表明对生物多样性具有积极的影响。关于覆盖作物掺入后养分有效性变化的证据有限，然而，覆盖作物残留物对杂草抑制的剂量依赖性效应表明化感作用和/或养分有效性可能对杂草种子发芽成功具有一定作用。一起，