Interest in cover crops is increasing but information is limited on integrating them into crop rotations especially in the relatively short growing season on the northern Great Plains. A 3-yr research project, initiated in 2009 near Mandan, North Dakota, USA, evaluated (1) what impact cover crops may have on subsequent cash crops yields and (2) whether cover crop mixtures are more productive and provide additional benefits compared to cover crop monocultures. The study evaluated 18 different cover crop monocultures and mixtures that were seeded in August following dry pea (Pisum sativum L.). The following year, spring wheat (Triticum aestivum L.), corn (Zea mays L.), soybean (Glycine max L.) and field pea were seeded into the different cover crop treatments and a non-treated control. A lack of timely precipitation in 2009 resulted in a low cover crop yield of 17 g m2 compared to 100 and 77 g m2 in 2008 and 2010, respectively. Subsequent cash crop yield was not affected by late-seeded cover crops. Cool-season cover crop monocultures were more productive than warm-season monocultures and some mixtures in 2008 and 2010. Relative yield total did not differ from one in any cover crop mixture suggesting that overyielding did not occur. Species selection rather than species diversity was the most important contributor to cover crop yield. Cover crops can be grown following short-season cash crops in the northern Great Plains, but precipitation timing and species selection are critical.

中文翻译：

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半干旱环境中的晚播覆盖作物：超产、优势和随后的作物产量

对覆盖作物的兴趣正在增加，但关于将它们纳入轮作的信息有限，特别是在大平原北部相对较短的生长季节。一个为期 3 年的研究项目于 2009 年在美国北达科他州曼丹附近启动，评估了 (1) 覆盖作物可能对随后的经济作物产量产生什么影响，以及 (2) 覆盖作物混合物是否更具生产力并提供额外的好处覆盖作物单一栽培。该研究评估了 8 月在干豌豆后播种的 18 种不同的覆盖作物单一栽培和混合物（豌豆L.)。次年，春小麦（小麦L.), 玉米 (玉米L.), 大豆 (最大甘氨酸L.) 和豌豆被播种到不同的覆盖作物处理和未处理的对照中。2009 年缺乏及时降水导致覆盖作物单产低至 17 克2与 100 克和 77 克相比2分别在 2008 年和 2010 年。随后的经济作物产量不受晚播覆盖作物的影响。2008 年和 2010 年，冷季覆盖作物单一栽培比暖季单一栽培和一些混合作物的产量更高。相对总产量与任何覆盖作物混合物中的一个没有差异，这表明没有发生超产。物种选择而不是物种多样性是覆盖作物产量的最重要因素。覆盖作物可以在大平原北部的短季经济作物之后种植，但降水时间和物种选择至关重要。