Deep fertilizer placement is a proposed strategy to increase crop yield and nitrogen (N) use efficiency while decreasing nitrous oxide (N₂O) emissions from soil to atmosphere. Our objective was to test three fertilization depth orientations to compare overall N use efficiency, based on a 2-year field trial on a mineral soil cropped with cereals in Uppsala, Sweden. The field was fertilized with ammonium nitrate at a rate of 120 kg ha⁻¹ (2016) and 105 kg ha⁻¹ (2017) and a deep fertilizer placement (DP) at 0.20 m was compared to a shallow placement (SP) at 0.07 m and a mixed-depth placement (MP) where fertilizer was halved between the depths of 0.07 and 0.20 m, and a non-fertilized control (NF). In 2016, compared to SP, MP and DP increased N content in harvested grain by 3.6% and 2.5% respectively, and DP increased grain yield by 11% (P < 0.05). In both years, N₂O emissions were similar in DP and NF, whereas SP and MP emissions were similar but generally higher than those in DP and NF. Fertilizer-induced emission factors (EF) for the growing season of 2017 decreased with fertilizer placement depth and were 0.77 ± 0.07, 0.58 ± 0.03, and 0.10 ± 0.02 for SP, MP, and DP, repectively. Although deep N placement benefits are likely dependent on weather conditions and soil type, this strategy has a clear potential for mitigating N₂O emissions without adversely affecting yield.

深层施肥是提高作物产量和氮（N）利用率同时减少从土壤到大气中的一氧化二氮（N ₂ O）排放的拟议策略。我们的目标是根据瑞典乌普萨拉的一种以谷物种植的矿物土壤进行的为期2年的田间试验，测试三种施肥深度方向，以比较整体氮素利用效率。用硝酸铵以120 kg ha ^-1（2016）和105 kg ha ^-1的速度施肥（2017年），将0.20 m处的深肥（DP）与0.07 m处的浅肥（SP）和0.07和0.20 m深度之间的肥料减半的混合深度（MP）相比较，非受精对照（NF）。2016年，与SP相比，MP和DP使收获谷物中的氮含量分别增加3.6％和2.5％，而DP使谷物产量增加11％（P  <0.05）。两年中N ₂DP和NF的O排放相似，而SP和MP的排放相似，但通常高于DP和NF。2017年生长期的肥料诱导排放因子（EF）随施肥深度的增加而降低，SP，MP和DP分别为0.77±0.07、0.58±0.03和0.10±0.02。尽管深施氮的好处可能取决于天气条件和土壤类型，但该策略在减轻N ₂ O排放而又不影响产量方面具有明显的潜力。