Knowledge of how agricultural management interacts with weed seed banks and emergent weed communities is crucial for proactive weed management. Though studies have detailed how differences in disturbance and nutrient applications between organic and conventional herbicide‐based systems affect weed communities, few have focused on these same factors in contrasting organic systems. This study assessed the seed banks and emergent weed communities from the most recent crop rotation cycle (2017–2022) of a long‐term experiment, which compared four organic grain and forage cropping systems differing in nutrient inputs and soil disturbance. The high fertility (HF) system received high‐rate nutrient applications, low fertility (LF) received low‐rate applications, enhanced weed management (EWM) focused on weed control through frequent soil disturbance, and reduced tillage (RT) prioritized soil health with less intense or frequent soil disturbance. Soil samples for greenhouse germination assays were collected at the beginning (2017) and end (2022) of the rotation to explore how these four systems influenced seed bank dynamics over time. Weed community biomass was also sampled in each crop during this time. Treatment effects on weed abundance, taxonomic diversity, and community‐weighted means and functional dispersion of weed traits were analyzed with generalized mixed‐effect models. The RT system had the highest weed seed bank taxonomic diversity, and EWM had the lowest. RT and LF had higher functional dispersion of traits than HF in the seed bank. Weed seed bank communities in HF and RT were characterized by short, small‐seeded, and early germinating weed species. However, seed banks were also labile: Differences between systems in seed density and all other mean trait values were dependent on the crop, which preceded seed bank sampling. Likewise, differences among emergent weed communities in the four systems depended on an interaction between crop species and their planting year. Results suggest that resource availability and intensity of disturbance act as weed community assembly filters in organic cropping systems. Organic growers seeking to design systems that balance weed management and production goals can use relatively low soil disturbance and nutrient application to increase weed community taxonomic or functional diversity without necessarily increasing weed biomass or seed bank density.

中文翻译：

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肥力和耕作强度影响长期有机系统中的杂草群落多样性和功能结构


了解农业管理如何与杂草种子库和新兴杂草群落相互作用对于主动杂草管理至关重要。尽管研究详细介绍了有机系统和传统除草剂系统之间干扰和养分施用的差异如何影响杂草群落，但很少有人关注对比有机系统中的这些相同因素。本研究评估了长期实验的最近轮​​作周期（2017-2022）的种子库和新兴杂草群落，比较了养分投入和土壤扰动不同的四种有机谷物和饲料种植系统。高肥力（HF）系统接受高频率的养分施用，低肥力（LF）接受低频率的施用，强化杂草管理（EWM）侧重于通过频繁的土壤扰动控制杂草，而减少耕作（RT）则优先考虑土壤健康，不太强烈或频繁的土壤扰动。在轮作开始（2017 年）和结束（2022 年）收集用于温室发芽测定的土壤样本，以探索这四个系统如何随时间影响种子库动态。在此期间，还对每种作物的杂草群落生物量进行了采样。使用广义混合效应模型分析了处理对杂草丰度、分类多样性以及杂草性状的群落加权平均值和功能分散度的影响。 RT 系统的杂草种子库分类多样性最高，EWM 的分类多样性最低。种子库中RT和LF的性状功能离散度高于HF。 HF 和 RT 的杂草种子库群落的特点是短、小种子和早发芽的杂草物种。 然而，种子库也不稳定：系统之间的种子密度和所有其他平均性状值之间的差异取决于作物，而作物是在种子库采样之前进行的。同样，四个系统中新兴杂草群落之间的差异取决于作物种类及其种植年份之间的相互作用。结果表明，资源可用性和干扰强度在有机种植系统中起到了杂草群落组装过滤器的作用。寻求设计平衡杂草管理和生产目标的系统的有机种植者可以使用相对较低的土壤干扰和养分施用来增加杂草群落分类或功能多样性，而不必增加杂草生物量或种子库密度。