Integrating cover crops (CCs) into dryland crop rotations could provide options for herbicide-resistant (HR) weed control in no-tillage (NT) systems. Field experiments investigated weed suppression potential of spring-planted CCs and their effects on plant available water, crop yields, and net returns. The CC treatments were implemented during the fallow phase of NT wheat (Triticum aestivum L)–sorghum (Sorghum bicolor Moench)–fallow rotation at two locations: Brownell and Colby, over 3 yr in western Kansas. Treatments were oat–triticale (OT), oat–triticale–pea (Pisum sativum; OTP), spring pea, and fallow. Spring pea aboveground biomass was 3,290 kg ha⁻¹, whereas OT produced 5,640 kg ha⁻¹ and OTP produced 5,260 kg ha⁻¹. Regardless of location, weed biomass was reduced between 86 and 99% with CCs relative to weedy fallow. Cover crops reduced plant available water at winter wheat planting in three out of the six site-years. Averaged across years, CCs reduced winter wheat yields by 18% compared with fallow at Brownell but not at Colby. Replacing fallow with spring pea increased gross revenue but generated negative net returns because of high cost of herbicide and pea seed. Net return with OT or OTP CCs were negative in four out of six site-years when used strictly for weed suppression. However, net returns were mostly positive when OT ($110–876) or OTP (−$110–832) CCs were used as forage. Our results showed replacing fallow with spring-planted CCs for weed suppression in dryland cropping system is profitable only when the CCs are used for forage.

中文翻译：

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春季覆盖作物对免耕旱地作物生产中杂草抑​​制、作物产量和净收益的影响

将覆盖作物 (CCs) 整合到旱地轮作中可以为免耕 (NT) 系统中的抗除草剂 (HR) 杂草控制提供选择。田间试验研究了春季种植的 CCs 的杂草抑制潜力及其对植物有效水、作物产量和净收益的影响。CC 处理是在 NT 小麦 ( Triticum aestivum L)-高粱 ( Sorghum bicolor Moench)-休耕期在两个地点实施的：Brownell 和 Colby，在堪萨斯州西部超过 3 年。处理方法是燕麦-小黑麦 (OT)、燕麦-小黑麦-豌豆 ( Pisum sativum ; OTP)、春豌豆和休耕。春豌豆地上生物量为 3,290 kg ha ^-1，而 OT 产生 5,640 kg ha ^-1OTP 生产了 5,260 公斤公顷^-1. 无论位置如何，与杂草休耕相比，CCs 的杂草生物量减少了 86% 到 99%。在六分之三的种植地点覆盖作物减少了冬小麦种植时的植物可用水量。多年平均而言，与布朗内尔的休耕相比，CCs 将冬小麦产量降低了 18%，而在科尔比则没有。用春豌豆代替休耕增加了总收入，但由于除草剂和豌豆种子的高成本，产生了负的净回报。当严格用于杂草抑制时，使用 OT 或 OTP CC 的净回报在六分之四的站点年中为负。然而，当使用 OT ($110–876) 或 OTP (-$110–832) CCs 作为草料时，净回报大多为正。我们的结果表明，在旱地种植系统中，用春播的 CCs 代替休耕来抑制杂草只有当 CCs 用于草料时才是有利可图的。