The integration of cover crops (CCs) in low-input systems is a widely adopted practice to re-capture surplus nitrogen (N) and avoid excessive losses to the environment by leaching or N₂O emissions. Closing the N cycle within an agricultural system is therefore economically beneficial and lowers the negative impact of inorganic N on soil and water bodies. However, it is debated if pollution swapping occurs to some extent and if N₂O emissions increases as a result of decreased N leaching. An experiment was conducted to systematically evaluate grass vs. non-grass CCs, frost tolerant vs. non-frost tolerant CCs as well as high residual N vs. low residual N from the pre-crop, in a low input system which receives no additional fertilizer. Furthermore, the extent to which N₂O losses occur from different seeded CC species and mixtures (Sinapis alba/Vicia sativa, Brassica rapa/Vicia villosa and Lolium perenne/Trifolium repens) was investigated over two experimental years on a sandy soil located in northern Germany. The annual N₂O emissions were investigated on a weekly basis using the static closed chamber method. The non-grass CCs had the highest annual N₂O emissions (2.5 kg N₂O-N ha⁻¹) compared to grass (1.9 kg N₂O-N ha⁻¹). The frost-killed CC led to higher N₂O emissions (3.3 kg N₂O-N ha⁻¹), especially after the first year when high residual N was still present due to the pre-crop. This indicates that the type of CC used, frost tolerance as well as residual N from the pre-crop will affect N₂O emissions. The low N₂O emissions observed in the current study indicate that pollution swapping as a result of avoided N leached due to the use of CCs, as shown in a previous paper from the same experiment, is not occurring under these low-input systems. Furthermore, grass used as CC has low N₂O emissions and a high N uptake and therefore the potential to close the N cycle and improve on-farm N budgets.

将覆盖作物 (CC) 纳入低投入系统是一种广泛采用的做法，用于重新捕获多余的氮 (N)，并避免因淋滤或 N ₂ O 排放而对环境造成过度损失。因此，在农业系统内关闭氮循环具有经济效益，并减少无机氮对土壤和水体的负面影响。然而，污染交换是否发生一定程度以及N ₂ O排放量是否因氮淋滤减少而增加仍存在争议。进行了一项实验，以系统地评估草与非草 CC、耐霜与不耐霜 CC 以及预作中的高残留氮与低残留氮，在不接受额外的低投入系统中肥料。此外，在位于北部的沙质土壤上进行了两年的实验，研究了不同种子 CC 物种和混合物（白芥子/蚕豆、白菜/野豌豆和黑麦草/白三叶草）发生 N ₂ O 损失的程度。德国。采用静态密闭室法每周调查年度 N _{2 O 排放量。与草（1.9 kg N 2} O-N ha ^-1）相比，非草CC的年N ₂ O排放量最高（2.5 kg N ₂ O-N ha ^-1）。霜冻CC导致更高的N ₂ O排放（3.3 kg N ₂ O-N ha ^-1），特别是在第一年之后，由于作物前期，仍然存在高残留氮。这表明所使用的CC 类型、抗冻性以及前茬作物中残留的N 都会影响N ₂ O 排放。当前研究中观察到的低 N ₂ O 排放表明，在这些低投入系统下，由于使用 CC 避免了 N 浸出而导致的污染交换（如同一实验的先前论文所示）并未发生。此外，用作 CC 的草具有较低的 N ₂ O 排放量和较高的氮吸收量，因此具有闭合氮循环和改善农场氮预算的潜力。