A high recovery of applied fertilizer nitrogen (N) is required to minimize the environmental impact and to achieve high grain protein concentrations (GPC). Based on a long-term field trial (1976–2018) with winter wheat in northern Germany with 64 N fertilizer treatments differing in amount (0–360 kg N ha⁻¹) and distribution, the effects of N fertilizer amount and variety on the apparent fertilizer N recovery (AFR) of three application dates were determined. In addition, the relationship between grain yield (GY) and GPC was analyzed.

Apparent fertilizer N recovery was lowest for N applied at the beginning of spring growth (N1), but highest if applied at ear emergence (N3). It decreased with increasing N amounts. Newer varieties, cvs. Tommi and Julius (released in 2002 or 2008), achieved higher AFR than those released in 1993 and earlier (cvs. Diplomat, Kanzler, Orestis, Ritmo), especially that of late-season N due to both increased GY and GPC.

When estimating the correlation between GY and GPC and the effect of N3 on it, the amount of N fertilization applied before ear emergence (sum of N applied at the beginning of spring growth (N1) and N applied at the beginning of stem elongation (N2)) has to be taken into account, because N1 + N2 affects the source size of N which can remobilized and translocated into the grain. For the older varieties, a negative linear correlation between GY and GPC was found; however, in the treatments with N1 + N2 = 120, 160 and 200 kg N ha⁻¹, the newer varieties responded differently with firstly a decrease in grain protein concentration with increasing grain yield, but then achieving a plateau, namely GPC remained stable with rising GY. Probably, this was due to a more pronounced post-anthesis N uptake.

为了最大限度地减少对环境的影响并实现高谷蛋白浓度（GPC），需要高施氮肥（N）的回收。基于德国北部冬小麦的长期田间试验（1976–2018），使用64种氮肥，其处理量（0-360 kg N ha ^-1）和分布不同，氮肥用量和品种对小麦的影响确定了三个施用日期的表观肥料氮回收率（AFR）。另外，分析了谷物产量（GY）和GPC之间的关系。

在春季生长开始时施用的氮（N1）的表观肥料氮回收率最低，但在穗出苗时施用的表观肥料氮回收率最高（N3）。它随着氮含量的增加而降低。较新的品种，简历。Tommi和Julius（于2002年或2008年发行）取得的AFR高于1993年及之前（Diplomat，Kanzler，Orestis，Ritmo的发行人）发行的AFR，尤其是由于GY和GPC均增加而导致的后期N。

估算GY和GPC之间的相关性以及N3对它的影响时，在耳朵出苗之前施用的氮肥量（春季生长开始时施用的N的总和（N1）和茎伸长开始时施用的N的总和（N2） ）），因为N1 + N2会影响N的来源大小，而N会被迁移并转移到谷物中，因此必须予以考虑。对于较早的品种，发现GY和GPC之间呈负线性相关；但是，在N1 + N2 = 120、160和200 kg N ha ^{-1的处理中}，新品种的反应不同，首先是随着籽粒产量的增加而降低了谷物蛋白浓度，但随后达到了平稳状态，即GPC保持稳定。 GY上升。可能是由于花后氮吸收更加明显。