Straw incorporation and cover cropping are important measures for reducing loss of nitrate by leaching and supporting soil quality in cereal cropping systems. However, cereal straw also represents an important source of bioenergy, while concerns still exist regarding a negative effect of annual straw incorporation on crop yields. Based on a field experiment initiated in 1981 on a sandy loam soil at Askov Experimental Station (Denmark), we examined the effect of annual addition of straw (0, 4, 8 and 12 Mg ha⁻¹), undersown cover crops (ryegrass and ryegrass-clover), and ploughing time (autumn and spring) on spring barley yields and N uptake in grain and grain-free aboveground biomass. During 1981–2019, grain yields showed an annual increase of 0.05 Mg DM ha⁻¹ while grain N concentration decreased 0.019 %-point yr⁻¹. Straw incorporation rate had a significant effect on grain yield in only six out of 31 years. The effect of increasing straw rates was slightly negative in two of the initial years but positive in the extreme drought year 2018. During 2004–2018, an undersown grass-clover cover crop increased grain yield with 0.41 Mg DM ha⁻¹ and grain N concentration with 0.13 %-point, corresponding to relative increases of 9% when compared to no cover crop. In contrast, an undersown ryegrass cover crop reduced grain yield with 0.21 Mg DM ha⁻¹ corresponding to a relative reduction of 5%, and increased grain N concentration with 0.03 %-point corresponding to a relative increase of 2%, as compared to no cover crop. The time of incorporating straw and cover crop residues had a minor effect on barley yield and quality. Our results suggest that removal of straw for bioenergy does not compromise yields of spring barley grown at this site, while an inclusion of undersown leguminous cover crops had a pronounced positive impact on crop yield and quality. However, implementation of these management measures needs to be site-specific and consider trade-offs between effects on crop yield and quality, environmental benefits, and soil quality.

在谷物种植系统中，秸秆掺入和覆盖种植是减少硝酸盐流失和支持土壤质量的重要措施。然而，谷物秸秆也是一种重要的生物能源来源，同时人们仍然担心每年秸秆掺入对作物产量的负面影响。基于 1981 年在阿斯科夫实验站（丹麦）的沙壤土上开始的田间试验，我们检查了每年添加秸秆（0、4、8 和 12 Mg ha ^-1）、下播覆盖作物（黑麦草和黑麦草-三叶草）和耕作时间（秋季和春季）对春季大麦产量和谷物和无谷物地上生物量的氮吸收量的影响。1981-2019 年期间，粮食产量显示每年增加 0.05 Mg DM ha ^-1而谷物 N 浓度下降了 0.019 %-point yr ^-1。31 年中只有 6 年秸秆掺入率对粮食产量有显着影响。在最初的两年中，增加秸秆用量的影响略微为负，但在 2018 年极端干旱年为正。在 2004-2018 年期间，播种不足的三叶草覆盖作物增加了谷物产量，0.41 Mg DM ha ^-1和谷物 N 浓度有 0.13 个百分点，与没有覆盖作物相比，相对增加了 9%。相比之下，播种不足的黑麦草覆盖作物降低了谷物产量，0.21 Mg DM ha ^-1对应于 5% 的相对减少，并且与没有覆盖作物相比，谷物 N 浓度增加了 0.03% 点对应于 2% 的相对增加。秸秆和覆盖作物残留物的掺入时间对大麦产量和品质的影响较小。我们的结果表明，为生物能源去除秸秆不会影响该地点种植的春大麦的产量，而加入未播种的豆科覆盖作物对作物产量和质量有明显的积极影响。然而，这些管理措施的实施需要因地制宜，并考虑对作物产量和质量、环境效益和土壤质量的影响之间的权衡。