Fields are typically kept fallow after winter wheat (Triticum aestivum L.) grain harvest in the U.S. southern Great Plains (SGP). Introducing summer cover crops to the system could increase soil conservation and farm profitability if grazed. The objective of this research was to evaluate cover crops’ forage yield, residue cover potential, weed suppression, and effect on wheat production. Monocultures and grass–legume mixtures of cover crops were established in mid‐June of 2016 and 2017 near Chickasha and Perkins, OK. At 6 weeks after planting (WAP), three cutting regimes based on stubble height were used: severe (2.5 cm), recommended (legumes: 7.5 cm, grasses and mixtures: 15 cm), and no cutting. Cover crops regrowth was chemically terminated at 14 WAP; winter wheat was no‐till seeded in mid‐October; then harvested in early‐June 2017 and 2018. Cultivar Triple Treat sorghum−sudangrass [Sorghum bicolor (L.) Moench × S. bicolor var. sudanese] and grass−legume mixtures showed the greatest available forage dry matter. Grasses and grass−legume mixtures had greater forage dry matter residue and weed suppression than legumes. Results indicated that exceeding 6.4 ± 1.2 Mg ha⁻¹ of total dry matter (TDM) produced during the summer, a wheat grain yield penalty of −50.1 ± 15.8 kg ha⁻¹ resulted for each increment of 1.0 Mg ha⁻¹ of TDM produced. Also, a wheat protein content penalty of −1.9 ± 0.5 kg ha⁻¹ resulted in each increment of 1.0 Mg ha⁻¹ of TDM produced when exceeding to 5.7 ± 1.0 Mg ha⁻¹ TDM threshold. Findings suggest N uptake by high‐biomass grasses and mixtures might result in deficient water and N availability for wheat production.

中文翻译：

---

在俄克拉荷马州的冬小麦系统中引入可食草覆盖作物

冬小麦（Triticum aestivumL.）美国南部大平原（SGP）的谷物收成。如果放牧，将夏季覆盖作物引入该系统可以提高土壤保护和农场的盈利能力。这项研究的目的是评估覆盖作物的草料产量，残留物覆盖潜力，杂草抑制作用以及对小麦产量的影响。2016年6月中旬和2017年在俄克拉荷马州奇卡夏和珀金斯附近建立了单作作物和覆盖作物的草-豆混合物。种植后第6周（WAP），根据残茬高度使用了三种切割方式：严重（2.5厘米），推荐（豆类：7.5厘米，草和混合物：15厘米）和不切割。覆盖作物的再生长在14 WAP时化学终止。冬小麦在10月中旬开始播种。然后在2017年6月上旬和2018年6月初收获。品种三重对待高粱-苏丹草[高粱双色（L.）Moench× S. bicolor var。苏丹草和豆类混合物显示出最大的可用牧草干物质。草和豆类混合物比豆类具有更大的草料干物质残留和杂草抑制能力。结果表明，夏季生产的总干物质（TDM）超过6.4±1.2 Mg ha ^-1，则每增加1.0 Mg ha ^-1产生的小麦籽粒产量损失为-50.1±15.8 kg ha ^-1。。而且，小麦蛋白含量罚-1.9±0.5公斤公顷^-1导致1.0镁公顷的每个增量^-1超过5.7时TDM的产生±1.0镁公顷^-1TDM阈值。研究结果表明，高生物量草和混合物吸收的氮可能导致小麦生产中水分和氮的有效性不足。