Macronutrient inputs to annual cropping systems can benefit weeds as well as crops, sometimes decreasing or eliminating the benefits of fertilization. This interaction between fertility management and integrated weed management is becoming increasingly important as these fields increase their focus on efficiency and prevention, respectively. The risk of increased weed competition reflects the fact that weed biomass and height may be highly responsive to nitrogen, phosphorus, and/or potassium. This generalization is supported by monoculture studies of species such as redroot pigweed (Amaranthus retroflexus L.), common lambsquarters (Chenopodium album L.), and barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] and by ecological theory. However, field studies indicate variation in the effects of macronutrients on weed–crop competition and crop yield, even within species groups. To address challenges in interpreting, comparing, and extrapolating from these diverse reports, we propose a conceptual framework that summarizes the mechanisms underlying observed variation within and between studies. This framework highlights functional traits and trends that help predict yield outcomes in binary weed–crop interactions. Important factors include timing of emergence, maximum heights of the weed and crop, and relative responsiveness to the added nutrient. We also survey recent work on the effects of nutrient source (e.g., the composition of organic amendments) on weed–crop competition. Because different sources vary in their nutrient release dynamics and supplied nutrient ratios, they may have dramatically different effects on weed–crop competition and crop yield. Finally, we offer a guide to best practices for studies of fertility effects on weed–crop competition. Although this review highlights several topics requiring further research, including fertility effects on multispecies interactions and interactions with other environmental factors, emerging methods offer considerable promise. Ultimately, an improved understanding of nutrient effects on weed–crop competition will contribute to the efficient and effective management of diverse cropping systems.

中文翻译：

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肥力改良对杂草生长和杂草-作物竞争的影响：综述

一年生种植系统的常量营养素投入可以使杂草和作物受益，有时会降低或消除施肥的益处。随着这些领域分别增加对效率和预防的关注，生育管理和综合杂草管理之间的这种相互作用变得越来越重要。杂草竞争加剧的风险反映了杂草生物量和高度可能对氮、磷和/或钾高度敏感的事实。这种概括得到了对红根藜等物种的单一栽培研究的支持。苋菜L.), 普通羔羊肉 (藜专辑L.) 和稗草 [稗草(L.) P. Beauv.] 和生态学理论。然而，实地研究表明常量营养素对杂草-作物竞争和作物产量的影响存在差异，即使在物种组内也是如此。为了解决从这些不同报告中解释、比较和推断的挑战，我们提出了一个概念框架，该框架总结了研究内部和研究之间观察到的变化背后的机制。该框架突出了有助于预测二元杂草-作物相互作用中产量结果的功能特征和趋势。重要因素包括出苗时间、杂草和作物的最大高度，以及对添加养分的相对反应。我们还调查了最近关于营养源（例如有机改良剂的组成）对杂草-作物竞争影响的研究。由于不同来源的养分释放动态和提供的养分比例不同，它们可能对杂草-作物竞争和作物产量产生显着不同的影响。最后，我们提供了研究生育力对杂草-作物竞争影响的最佳实践指南。尽管这篇综述强调了几个需要进一步研究的主题，包括对多物种相互作用和与其他环境因素相互作用的生育力影响，但新兴方法提供了相当大的希望。最终，更好地理解养分对杂草-作物竞争的影响将有助于高效和有效地管理不同的种植系统。我们提供了研究生育力对杂草作物竞争影响的最佳实践指南。尽管这篇综述强调了几个需要进一步研究的主题，包括对多物种相互作用和与其他环境因素相互作用的生育力影响，但新兴方法提供了相当大的希望。最终，更好地理解养分对杂草-作物竞争的影响将有助于高效和有效地管理不同的种植系统。我们提供了研究生育力对杂草作物竞争影响的最佳实践指南。尽管这篇综述强调了几个需要进一步研究的主题，包括对多物种相互作用和与其他环境因素相互作用的生育力影响，但新兴方法提供了相当大的希望。最终，更好地理解养分对杂草-作物竞争的影响将有助于高效和有效地管理不同的种植系统。