Abstract A significant drop of 2.4–2.9 percentage-points (%-p) in crude protein content (on dry matter basis) in Danish grain crops was observed from around 1990 to 2015. The aim of the analysis was to quantify the effect of the change in N-response of varieties of winter wheat (WW) and spring barley (SB) under farmers’ conditions based on approx. 1000 fertilizer trials with WW and 500 with SB carried out in farmers’ fields from 1987 to 2015. Results indicated that for WW receiving 129−190 kg N/ha, DM yield increased 0.8-0.9 Mg/ha. The amount of harvested N in grain increased 5−11 kg N/ha, and % N in grain dropped by 0.1-0.05 %-points; the largest drop was found for low N-additions. For SB, receiving 93−129 kg N/ha, DM yield increased by 0.9–1.1 Mg/ha. The amount of harvested N in grain increased by 4−6 kg while the N % in grain dropped 0.2-0.24 %-points. For both crops, the effect of plant breeding is likely to be confounded with the effect of increased CO2. Adding up effects of changed N-response and fertilizer rates only explained part of the observed reduction in crude protein content.

中文翻译：

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基于施肥试验中的氮响应分析 1990-2015 年丹麦粮食作物蛋白质含量的显着下降

摘要 1990 年至 2015 年左右，丹麦粮食作物的粗蛋白含量（以干物质计）显着下降了 2.4-2.9 个百分点 (%-p)。农民条件下冬小麦 (WW) 和春大麦 (SB) 品种氮响应的变化基于约 1987 年至 2015 年在农民田间进行了 1000 次施肥试验和 500 次施肥试验。结果表明，施施 129-190 kg N/ha 的 WW，DM 产量增加 0.8-0.9 Mg/ha。粮食中收获氮量增加5-11 kg N/ha，粮食中氮%下降0.1-0.05个百分点；发现低氮添加量下降幅度最大。对于 SB，接收 93-129 kg N/ha，DM 产量增加了 0.9-1.1 Mg/ha。粮食中收获的氮量增加了 4-6 kg，而粮食中的 N % 下降了 0.2-0。24%-点。对于这两种作物，植物育种的影响可能与二氧化碳增加的影响混淆。将改变的氮响应和施肥量的影响相加仅解释了观察到的粗蛋白含量减少的部分原因。