SUMMARYVegetable production systems are often characterized by excessive nitrogen (N) fertilization and the incorporation of large amounts of post-harvest crop residues. This makes them particularly prone to ammonia (NH3) and nitrous oxide (N2O) emissions. Yet, urgently needed management strategies that can reduce these harmful emissions are missing, because underlying processes are not fully understood. The present study therefore focuses on the effects of residue placement on NH3 and N2O emissions. For this, cauliflower leaf residues (286 kg N/ha) were either applied as surface mulch (mulch) or mixed with the topsoil (mix) and in situ NH3 and N2O emissions were investigated. The experiment took place on a sandy soil in Northeastern Germany during summer 2012. Residue application created a high peak in N2O emissions during the first 2 weeks, irrespective of residue placement. There was no significant difference in the emission sums over the experimental period (65 days) between the mix (5·8 ± 0·68 kg N2O-N/ha) and the mulch (9·7 ± 1·53 kg N2O-N/ha) treatment. This was also the case for NH3 emissions, which exhibited a lower initial peak followed by a prolonged decline. Measured emission sums were 4·1 ± 0·33 (mix) and 5·1 ± 0·73 (mulch) kg NH3-N/ha. It was concluded that substantial NH3 and N2O emissions can occur after high input of available organic carbon and N even in a coarse-textured soil with low water-holding capacity. Other than expected, surface-application does not enhance NH3 emissions at the expense of N2O emissions compared with residue mixing into the soil, at least under the conditions of the present study.

中文翻译：

---

表面施用和掺入花椰菜叶残渣后沙质土壤中的一氧化二氮和氨的排放

摘要蔬菜生产系统的特点通常是过度施氮（N）施肥和大量收获后作物残留物的掺入。这使得它们特别容易产生氨（NH3) 和一氧化二氮 (N2O) 排放。然而，由于尚未完全了解基本过程，因此缺少可以减少这些有害排放的迫切需要的管理策略。因此，本研究侧重于残基放置对 NH 的影响3和 N2O 排放。为此，将花椰菜叶残渣（286 kg N/ha）用作表面覆盖物（覆盖物）或与表土混合（混合）和原位NH3和 N2研究了 O 排放。该实验于 2012 年夏季在德国东北部的沙质土壤上进行。残留施用在 N2前 2 周内的 O 排放，与残留物放置无关。在实验期间（65 天），混合（5·8 ± 0·68 kg N）的排放总量没有显着差异2ON/ha) 和覆盖物 (9·7 ± 1·53 kg N2ON/ha) 处理。NH也是如此3排放量，其初始峰值较低，随后长期下降。测得的排放总和为 4·1 ± 0·33（混合）和 5·1 ± 0·73（覆盖）kg NH3-N/公顷。结论是大量 NH3和 N2即使在具有低持水能力的粗质地土壤中，大量输入有效有机碳和氮后也会发生 O 排放。与预期不同的是，表面应用不会增强 NH3以 N 为代价的排放2至少在本研究的条件下，与混入土壤的残留物相比，O 排放。