Planting cover crops within or following a cash crop may improve soil-based ecosystem services due to increased plant diversity and a longer duration of live vegetation coverage. We examined the effect of three different cover cropping systems on soil properties after one year of a three-year organic transition rotation at four agricultural field sites with contrasting topographical positions, namely depressions, slopes, and summits. The four studied systems were (1) cereal rye (Secale cereal L.) planted after corn (Zea mays L.) harvest (Rye); (2) a mixture of cold susceptible cover crop species, namely, oat (Avena sativa), winter pea (Pisum sativum), and radish (Raphanus sativus), interseeded into corn (WK); (3) a mixture of cold tolerant cover crop species, namely, annual ryegrass (Lolium multiflorum), Dwarf Essex rapeseed (Brassica napus), and crimson clover (Trifolium incarnatum), interseeded into corn (WH); and (4) a no-cover control (NC). While soil moisture was affected by topography, interseeding cover crops into corn did not influence soil moisture levels at the 0–10 cm depth for the studied year. Soil NO₃^- content was markedly higher in the WK system compared to cereal rye and WH cover crop treatments. The difference was especially pronounced in depressions and summits. Soil N mineralization rates followed the pattern WH>WK>Rye>NC and the effects were most pronounced in slopes. Soil microbial biomass C was the highest in depressions followed by summits and slopes, and in depressions the WH had higher microbial biomass than the other systems. There were no effects of cover crops and topography on soil C mineralization one year after the organic transition was initiated. The WH system increased the fraction of 0.053–2 mm aggregates and decreased > 2 mm aggregates in depressions. The results suggest that the effect of cover cropping can become evident already one year after the organic transition begins. The WH mixture interseeded into the cash crop was an optimal cover crop choice for improving soil characteristics as well as decreasing soil N leaching risks during organic transition in undulating agricultural terrain. However, the magnitude of the benefit provided by WH was mediated by topography.

由于植物多样性增加和活植被覆盖持续时间更长，在经济作物内或之后种植覆盖作物可能会改善以土壤为基础的生态系统服务。我们在具有对比的地形位置的四个农田地点（即洼地、斜坡和山顶）进行了为期三年的有机过渡轮作一年后，研究了三种不同的覆盖种植系统对土壤特性的影响。四个研究的系统是 (1)玉米 ( Zea mays L.) 收获后种植的谷物黑麦 ( Secale 谷物L.) (Rye)；(2) 寒冷易感覆盖作物物种的混合物，即燕麦 ( Avena sativa)、冬豌豆 ( Pisum sativum ) 和萝卜 ( Raphanus sativus)), 与玉米 (WK) 播种；(3)将一年生黑麦草( Lolium multiflorum )、矮油菜( Brassica napus )和深红三叶草( Trifolium incarnatum )等耐寒覆盖作物品种混种于玉米(WH)中；(4) 无覆盖控制 (NC)。虽然土壤水分受地形影响，但在研究年份，将覆盖作物播种到玉米中不会影响 0-10 厘米深度的土壤水分含量。土壤 NO ₃ ^-与谷物黑麦和 WH 覆盖作物处理相比，WK 系统中的含量显着更高。这种差异在洼地和山顶上尤为明显。土壤 N 矿化率遵循 WH>WK>Rye>NC 模式，在斜坡上影响最为显着。洼地土壤微生物生物量 C 最高，其次是山顶和斜坡，洼地中 WH 的微生物生物量高于其他系统。有机转变开始一年后，覆盖作物和地形对土壤碳矿化没有影响。WH 系统增加了 0.053-2 毫米聚集体的比例，并减少了凹陷中 > 2 毫米的聚集体。结果表明，在有机过渡开始一年后，覆盖作物的影响就会变得明显。将 WH 混合物播种到经济作物中是改善土壤特性以及降低起伏农业地形有机过渡期间土壤氮淋失风险的最佳覆盖作物选择。然而，WH 提供的益处的大小是由地形调节的。