Abstract Cover crop (CC) benefits and adoption in crop rotations may be limited by the short planting window after the cash crop. Interseeding or relay intercropping of CC is a technique that could overcome short planting windows constraints and allow CC establishment and growth. However, in Mediterranean regions this technique has been poorly implemented. Field experiments were established in Central Spain during two consecutive growing seasons to assess the performance of different species as interseeded crops into irrigated maize (Zea mays L.). The treatments included annual ryegrass (Lolium multiflorum L.) and eight legumes: burr medic (Medicago polymorpha L.), barrel medic (Medicago truncatula L.), yellow sweetclover (Melilotus officinalis L.), berseem clover (Trifolium alexandrinum L.), balansa clover (Trifolium michelanium L.), red clover (Trifolium pratense L.), Persian clover (Trifolium resupinatum L.), and common vetch (Vicia sativa L.). A bare soil was included as control treatment. After the maize harvest, the four species with the best performance were planted as autumn cover crops in adjacent plots. The ground cover was studied throughout the experimental period, and biomass and N content for each species were determined in the autumn and in the following spring prior to the cover crop termination. The soil inorganic N content was determined in spring. Barrel medic, yellow sweetclover, common vetch and annual ryegrass were the species with the best performance in terms of soil coverage during the summer. Red clover and Persian clover had good establishment in one out of two years. None of the interseeded species impaired maize grain yield or quality. Interseeded species achieved better soil coverage and increased the biomass accrued at autumn compared to cover crops sown in October. Therefore, interseeded species ensured longer ground coverage, increasing the potential for soil quality improvement or weed suppression. Moreover, the higher biomass achieved by interseeded species ensured the survival of yellow sweetclover, which was winter killed when planted in the autumn. Interseeded cover crops enhanced the potential of N leaching reduction compared to autumn cover crops. This experiment confirms the suitability of different species interseeded in summer into irrigated maize in Mediterranean regions, and highlights the extra benefits of this practice in annual rotations.

中文翻译：

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将覆盖作物播种到玉米中：地中海条件下物种表现的特征

摘要 覆盖作物 (CC) 的好处和轮作中的采用可能会受到经济作物种植时间短的限制。CC 的间种或中继间作是一种可以克服短种植窗口限制并允许 CC 建立和生长的技术。然而，在地中海地区，这种技术的实施效果不佳。在西班牙中部连续两个生长季节进行了田间试验，以评估不同物种在将作物间种到灌溉玉米 (Zea mays L.) 中时的性能。处理包括一年生黑麦草 (Lolium multiflorum L.) 和八种豆科植物：毛刺草 (Medicago polymorpha L.)、桶草 (Medicago truncatula L.)、黄三叶草 (Melilotus officinalis L.)、三叶草 (Trifolium alexandrinum L.) , balansa 三叶草 (Trifolium michelanium L.), 红三叶草 (Trifolium pratense L.)、波斯三叶草 (Trifolium resupinatum L.) 和野豌豆 (Vicia sativa L.)。包括裸土作为对照处理。玉米收获后，将表现最好的四个品种作为秋季覆盖作物种植在相邻地块中。在整个实验期间对地被植物进行了研究，并在秋季和次年春季覆盖作物终止前测定了每个物种的生物量和 N 含量。土壤无机氮含量在春季测定。木桶草、黄三叶草、紫云英和一年生黑麦草是夏季土壤覆盖率表现最好的品种。红三叶草和波斯三叶草在两年内有很好的建立。种间种种均未损害玉米籽粒产量或质量。与 10 月份播种的覆盖作物相比，种子间种实现了更好的土壤覆盖，并增加了秋季产生的生物量。因此，种子间种确保了更长的地面覆盖率，增加了土壤质量改善或杂草抑制的潜力。此外，种子间种获得的较高生物量确保了黄色甜三叶草的存活，秋季种植时冬季死亡。与秋季覆盖作物相比，间种覆盖作物增强了减少氮浸出的潜力。该实验证实了夏季在地中海地区将不同物种间种到灌溉玉米中的适用性，并强调了这种做法在年度轮作中的额外好处。因此，种子间种确保了更长的地面覆盖率，增加了土壤质量改善或杂草抑制的潜力。此外，种子间种获得的较高生物量确保了黄色甜三叶草的存活，秋季种植时冬季死亡。与秋季覆盖作物相比，间种覆盖作物增强了减少氮浸出的潜力。该实验证实了夏季在地中海地区将不同物种间种到灌溉玉米中的适用性，并强调了这种做法在年度轮作中的额外好处。因此，种子间种确保了更长的地面覆盖率，增加了土壤质量改善或杂草抑制的潜力。此外，种子间种获得的较高生物量确保了黄色甜三叶草的存活，秋季种植时冬季死亡。与秋季覆盖作物相比，间种覆盖作物增强了氮浸出减少的潜力。该实验证实了夏季在地中海地区将不同物种间种到灌溉玉米中的适用性，并强调了这种做法在年度轮作中的额外好处。秋天种植时被冬天杀死。与秋季覆盖作物相比，间种覆盖作物增强了氮浸出减少的潜力。该实验证实了夏季在地中海地区将不同物种间种到灌溉玉米中的适用性，并强调了这种做法在年度轮作中的额外好处。秋天种植时被冬天杀死。与秋季覆盖作物相比，间种覆盖作物增强了氮浸出减少的潜力。该实验证实了夏季在地中海地区将不同物种间种到灌溉玉米中的适用性，并强调了这种做法在年度轮作中的额外好处。