Storkey and Neve (2018) hypothesised that weed seedbank diversity could be used as an indicator of agroecosystem sustainability, with cropping systems associated with higher weed seedbank diversity being more agronomically and environmentally sustainable than those with lower weed diversity. We evaluated their hypothesis using multiple years of empirical data collected from a long-term field experiment in Iowa, USA, and life cycle assessment models parameterised with data from that experiment. We found that diversifying a 2-year maize–soyabean rotation with two additional crop phases, oat and lucerne, to form a 4-year rotation (a) increased Simpson's diversity index for weed species in the soil seedbank, while (b) increasing maize and soyabean productivity, (c) maintaining total crop energy production and profitability, and (d) reducing herbicide-related aquatic toxicity, fossil energy consumption, greenhouse gas emissions, damage to human health due to fine particulate matter, and discharge of soil sediment, nitrogen, and phosphorus. Increased weed biomass production and greater weed species diversity that occurred within oat and lucerne phases of the 4-year rotation sequence did not result in a loss of weed control within maize and soyabean phases of the rotation. We suggest that while there was no cause-and-effect relationship between greater weed seedbank diversity and improved agroecosystem sustainability in agronomic, economic and environmental dimensions, all of these responses were driven in a parallel manner by cropping system diversification. Consequently, weed seedbank diversity may indeed be a useful agroecosystem sustainability indicator. Further evaluation of this hypothesis in more systems is warranted.

中文翻译：

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杂草种子库的多样性和可持续性指标，可实现简单，多样化的种植体系

Storkey and Neve（2018）假设杂草种子库多样性可以用作农业生态系统可持续性的指标，与杂草种子库多样性较高相关的耕作系统比杂草种子多样性较低的农作物在农业和环境方面更具可持续性。我们使用从美国爱荷华州的长期现场实验收集的多年经验数据评估了他们的假设，并使用该实验数据对生命周期评估模型进行了参数化。我们发现，将玉米和大豆的2年轮作与燕麦和卢塞恩这两个额外的作物种植期多样化，以形成4年轮换（a）提高了土壤种子库中杂草种类的辛普森多样性指数，而（b）增加了玉米和大豆生产力，（c）维持作物能源总产量和利润率，（d）减少与除草剂有关的水生毒性，化石能源的消耗，温室气体的排放，细颗粒物对人类健康的损害以及土壤沉积物，氮和磷的排放。在4年轮作序列的燕麦和卢塞恩阶段发生的杂草生物量产量增加和杂草物种多样性增加，并未导致玉米和大豆轮作阶段失去对杂草的控制。我们建议，虽然在农业，经济和环境方面杂草种子库的多样性与改善的农业生态系统可持续性之间没有因果关系，但所有这些应对措施都是通过种植系统多样化以并行方式驱动的。因此，杂草种子库的多样性确实可能是一个有用的农业生态系统可持续性指标。