Cover crops (CC) can be used to reduce soil inorganic N (SIN) losses from agricultural soils. However, challenges exist in establishing CCs after corn (Zea mays L.) harvest in regions with a limited window for fall CC growth. One solution to this constraint is to establish a CC by interseeding into a standing corn crop. This experiment aims to assess the effect of interseeding CCs on the N cycle. Within organically managed corn grain and silage systems, we implemented three CC treatments: interseeded annual ryegrass (Lolium multiflorum Lam.), postharvest seeded cereal rye (Secale cereale L.), and a no-CC fallow. We applied fertilizer at a standard level (336 kg N ha⁻¹) and at a high level (420 kg N ha⁻¹). Silage was harvested in October and grain in November. Corn yields were not affected by CC treatments. In the fall in the silage system, the interseeded treatment had reduced SIN compared with the postharvest seeded treatment. In the spring, both interseeded and postharvest seeded treatments had less deep SIN than fallow in grain and silage. Under high N conditions in the spring, interseeded treatments had greater microbial biomass than all other treatment combinations. Both CC treatments and applied N levels affected microbial taxonomic groups. In terms of N retention services, interseeded CCs do have potential to outperform a postharvest seeded CC with a longer window for unshaded fall growth (as in a silage system) and may perform just as well as a postharvest seeded CC in the spring.

中文翻译：

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有机玉米系统中的间种覆盖作物提供的氮服务

覆盖作物 (CC) 可用于减少农业土壤中的土壤无机氮 (SIN) 损失。然而，在秋季 CC 生长窗口有限的地区，在玉米 ( Zea mays L.) 收获后建立 CC 存在挑战。这种限制的一种解决方案是通过将种子播种到站立的玉米作物中来建立 CC。本实验旨在评估播种 CC 对 N 循环的影响。在有机管理的玉米谷物和青贮饲料系统中，我们实施了三种 CC 处理：间种一年生黑麦草 ( Lolium multiflorum Lam.)、收获后播种的谷物黑麦 ( Secale graine L.) 和无 CC 休耕。我们以标准水平（336 kg N ha ^-1）和高水平（420 kg N ha ^-1）。10 月收获青贮饲料，11 月收获谷物。玉米产量不受CC处理的影响。在青贮系统的秋季，与采后播种处理相比，播种处理降低了 SIN。在春季，插播和采后播种处理的 SIN 深度均低于谷物和青贮饲料的休耕。在春季高氮条件下，间种处理比所有其他处理组合具有更大的微生物生物量。CC 处理和应用的 N 水平都影响微生物分类群。在氮保留服务方面，间种 CC 确实有可能优于采后播种 CC，具有更长的无遮蔽秋季生长窗口（如在青贮饲料系统中），并且可能与春季采后播种 CC 一样好。