Sustainable management of intensively managed agricultural land requires high productivity with low environmental impacts. There is a lack of understanding concerning the effectiveness of early sowing of winter cereals compared with catch crops for reducing nitrogen (N) leaching losses. To test this, an experiment was conducted over three years (2016–2019) with different crop rotations and increasing rates of N fertilisation. The experiment was done at two contrasting sites in Denmark; one of the sites was at Foulum (FU) on a sandy loam in a wetter climate and the other at Flakkebjerg (FB) on a sandy loam soil in a drier climate. The main crops were either spring barley (SB), or winter rye (WR) at FU and winter wheat (WW) at FB. The SB received four different N fertilisation rates ranging from 0 to 200 kg N ha⁻¹, and the winter cereals six different rates ranging from 0 to 255 for WR and from 0 to 300 kg N ha⁻¹ for WW. In the SB treatments the soil was either left bare over winter, or sown with volunteer barley plants or catch crops. The catch crop used at FU was ryegrass, while fodder radish was used at FB. The WR and WW were either sown timely, according to common practice at the end of September or about three weeks earlier. Neither early sowing nor the use of a catch crop affected the grain yield or the grain N concentration. Nitrate leaching was reduced on both sites by early sowing and by the use of a catch crop. Early sowing of WR at FU reduced N leaching compared to timely sowing, and had almost the same N leaching as the spring barley/ryegrass rotation. At FB, early sowing of WW also reduced N leaching compared to timely sowing, but this was only significant in one of the three years, and leaching was much higher than in the spring barley/fodder radish rotation. Both early sowing of winter cereals and the use of a catch crop in spring cereals are mitigation options for reducing N leaching.

对集约化管理的农业用地进行可持续管理需要高生产率且对环境的影响很小。对于减少谷物中氮（N）的浸出损失，与谷物相比，冬季谷物的早期播种的有效性缺乏了解。为了测试这一点，在三年（2016-2019年）中进行了一项实验，试验采用不同的作物轮作方法并增加了氮肥的施用率。实验是在丹麦的两个对比地点进行的；其中一个地点是在潮湿气候下的沙壤土上的富勒姆（FU），另一个是在干旱气候下的砂壤土上的弗拉克比约（FB）。主要农作物是FU的春大麦（SB）或冬黑麦（WR），以及FB的冬小麦（WW）。SB接受了4种不同的氮肥施用率，范围从0到200 kg N ha ^-1，以及冬季谷物的六种不同比率，WR分别为0至255和N ha ^-1为0至300 kg对于WW。在SB处理中，土壤要么在冬天裸露，要么用大麦志愿者植物或农作物播种。FU使用的农作物是黑麦草，而FB使用的是萝卜草。根据惯例，WR和WW要么及时播种，要么在9月底或大约三周前播种。早期播种和不使用连作作物都不会影响谷物的产量或氮的含量。通过早期播种和使用捕获作物，减少了两个地点的硝酸盐浸出。与适时播种相比，在FU早播WR减少了N的淋失，并且与春季大麦/黑麦草的轮作几乎相同。在FB，与适时播种相比，WW的早期播种还减少了N的淋失，但这仅在三年之一中很重要，并且浸出比春季大麦/饲料萝卜的旋转高得多。冬季谷物的早期播种和春季谷物中使用的农作物都是减少氮淋失的缓解方法。