Relay-cropping of the novel oilseeds winter camelina (Camelina sativa L.) and pennycress (Thlaspi arvense L.) with short-season crops such as soybean [Glycine max (L.) Merr.] can provide economic and environmental incentives for adopting winter cover crop practices in the U.S. Upper Midwest. However, their ability to reduce nutrient loss in surface runoff is unknown. Accordingly, surface runoff and quality were evaluated during three seasonal phases (cover, intercrop, and soybean) over 2 yr in four cover crop-soybean treatments (pennycress, winter camelina, forage radish [Raphanus sativus L.], and winter rye [Secale cereale L.]) compared with no-till and chisel-till fallow treatments. Runoff was collected with Gerlach troughs and assessed for concentrations and loads of NO3 - -N, total mineral N, soluble reactive P (SRP), and total suspended solids (TSS). Cumulative runoff and nutrient loads were greater during the winter cover phase because of increased snow melt and freeze-thaw released nutrients from living vegetation. In contrast, cumulative TSS was greater during intercrop and soybean phases due to high-intensity rainfall events with an open soybean canopy. Average TSS loads during the intercrop phase were reduced by 75% in pennycress compared with fallow and radish treatments. During the soybean phase, average TSS, total mineral N, and SRP loads were generally elevated in cover crop treatments compared with no-till. Overwintering cover crops may contribute to mobility of nutrients solubilized from living or decomposing vegetation; however, this was balanced by their potential to reduce runoff and TSS during high-intensity spring rains.

中文翻译：

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中西部北部覆盖作物-大豆系统的地表径流和养分动态


将新型油籽冬亚麻荠 (Camelina sativa L.) 和矮芥菜 (Thlaspi arvense L.) 与大豆 [Glycine max (L.) Merr.] 等短季作物套种可以为采用冬季作物提供经济和环境激励美国中西部北部的覆盖作物实践。然而，它们减少地表径流中养分流失的能力尚不清楚。因此，在 2 年多的时间里，对四种覆盖作物-大豆处理（矮芥菜、冬亚麻荠、饲料萝卜 [Raphanus sativus L.] 和冬黑麦 [Secale]）在三个季节阶段（覆盖作物、间作作物和大豆）的地表径流和质量进行了评估]）与免耕和凿耕休耕处理相比。使用 Gerlach 槽收集径流，并评估 NO3 - -N、总矿物质 N、可溶​​性活性磷 (SRP) 和总悬浮固体 (TSS) 的浓度和负荷。由于积雪融化和冻融从活植被中释放养分的增加，冬季覆盖阶段的累积径流和养分负荷更大。相比之下，由于大豆冠层开放的高强度降雨事件，间作和大豆阶段的累积 TSS 更大。与休耕和萝卜处理相比，矮芥菜间作阶段的平均 TSS 负荷减少了 75%。在大豆生长阶段，与免耕相比，覆盖作物处理的平均 TSS、总矿物氮和 SRP 负荷普遍升高。越冬覆盖作物可能有助于活体或腐烂植被溶解的养分的流动；然而，这与它们在高强度春雨期间减少径流和 TSS 的潜力相平衡。