Using dairy manure and legumes in crop rotations can reduce inorganic N inputs for corn (Zea mays L.), yet these practices can also contribute to nitrous oxide (N₂O) emissions. In two crop rotations we investigated how different (i) organic and inorganic N amendments and (ii) prior legume crops with broadcast manure influenced direct N₂O emissions from silt-loam soils planted to no-till corn. We measured N₂O fluxes from April to December for two years using closed vented chambers from soils planted to corn with no spring residue to compare inorganic N fertilizer (S-UAN) and two liquid dairy manure application methods: surface broadcasted (S-BM) and injected (S-IM). Emissions were also measured to compare the effect of crop residue of perennial forages, a green manure legume, or soybean (Glycine max L. Merr.) from soils all amended with liquid dairy manure. Nitrous oxide emissions were greatest during the 15–45 days after manure was injected compared to broadcasting, and cumulative N₂O emissions were larger from S-IM (2.8–2.5 kg ha⁻¹) than S-BM (1.4–0.7 kg ha⁻¹) and S-UAN (0.3 kg ha⁻¹). Cumulative and yield-scaled N₂O emissions did not differ among the prior legume treatments. A ranking approach based on random forests, identified the most important variable contributing to N₂O emissions in both comparisons as corn growing degree days, indicative of the asynchrony of spring legume termination and manure application with corn planting and N use; and changing environmental conditions for N mineralization and denitrification.

在轮作中使用奶牛粪肥和豆类作物可以减少玉米（Zea mays L.）的无机氮投入，但这些做法也可能导致一氧化二氮（N ₂ O）排放。在两次轮作中，我们研究了（i）有机和无机氮改良剂以及（ii）带有播撒肥料的先前豆类作物对种植于免耕玉米的粉壤土土壤直接N ₂ O排放的影响。我们测量了N ₂使用封闭的通风室从种植于没有春季残留物的玉米的土壤中抽出两年的4月至12月的O通量，以比较无机氮肥（S-UAN）和两种液体奶牛粪肥的施用方法：表面撒播（S-BM）和注入（ S-IM）。还测量了排放量，以比较均用液态奶肥改良过的土壤中多年生牧草，绿肥豆科植物或大豆（Glycine max L. Merr。）的作物残渣的影响。与广播相比，在粪肥注入后的15-45天内，一氧化二氮的排放量最大，S-IM（2.8-2.5 kg ha ^-1）的累积N ₂ O排放量大于S-BM（1.4-0.7 kg ha的）^-1）和S-UAN（0.3 kg ha ^-1）。在先前的豆类处理中，累积的N ₂ O和产量定额的N ₂ O排放没有差异。基于随机森林的分级方法，在两个比较中都将导致N ₂ O排放的最重要变量确定为玉米生长日，这表明春季豆科植物的终止以及玉米种植和氮肥的施用与施用不同步。以及改变氮矿化和反硝化的环境条件。