An increased nitrogen (N) supply was proposed to avoid grain yield (GY) reductions and successfully implement conservation agriculture (CA). We investigated interactions effects of tillage system and N supply on winter wheat (Triticum aestivum L.) at two sites in the Swiss midlands with no (0 kg N ha⁻¹) and high (150–160 kg N ha⁻¹) N supply using ¹⁵N-labelled ammonium nitrate in selected treatments. Wheat’s GY, yield components, N related traits and soil mineral N content (N_min) under conventional tillage (CT), minimum tillage (MT), and no-tillage (NT) were studied following two preceding crops: oilseed rape (Brassica napus L.) and maize (Zea mays L.). Wheat after oilseed rape had significantly higher GY and biomass than after maize while a yield decrease under NT compared with CT and MT was observed regardless of N supply level. Differences in soil N_min among tillage systems were seldom found and were inconsistent. No differences in ¹⁵N fertilizer recovery were found between NT and CT while residual N_min after harvest was lower under NT than CT or MT. In conclusion, we did not found consistent reductions in soil N availability and N uptake under NT that would justify an increased N supply for wheat under CA.

中文翻译：

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在凉爽和潮湿的条件下，免耕小麦均不需要提高氮肥利用率

提出增加氮（N）供应以避免谷物产量（GY）减少并成功实施保护性农业（CA）。我们调查了瑞士中部两个地点的耕作系统和氮素供应对冬小麦（Triticum aestivum L.）的交互作用，这两个地区的氮素供应量不高（0 kg N ha ^-1），氮素供应高（150-160 kg N ha ^-1）在选定的治疗方法中使用¹⁵ N标记的硝酸铵。小麦的GY，产量构成，N相关性状和土壤无机氮含量（N_分钟传统耕作（CT），少耕（MT），和免耕（NT）下）进行了研究以下两个前述作物：油籽油菜（甘蓝型油菜L.）和玉米（Zea maysL.）。油菜后的小麦的GY和生物量显着高于玉米，而在NT下与CT和MT相比，无论氮素供应水平如何，单产均下降。很少发现耕作系统中土壤N _min的差异，并且不一致。在没有差异¹⁵氮肥恢复被发现NT和CT之间，而残余Ñ_分钟收获后NT下低于CT或MT。总之，我们发现在氮下土壤氮素利用率和氮素吸收量没有持续减少，这足以证明在CA下小麦的氮素供应量增加。