Aim

The effects of residue type and distribution, soil moisture and NO₃⁻ availability were investigated in 43 days laboratory incubations (15 °C) on emissions of N₂O, CO₂, and for some treatments NO and NH₃.

Methods

Two crop residues were considered (red clover, RC, and winter wheat, WW), and they were either mixed with topsoil, placed as a discrete layer in soil, or no addition. Soil NO₃⁻ was either at ambient level or increased. Water filled pore space (WFPS) was adjusted to either 40 or 60%. All treatments were analysed for mineral N, N₂O and CO₂ with manual sampling and gas chromatography. Selected treatments were analysed with a continuous-flow method of N₂O and CO₂ by laser spectroscopy, NO by photoluminescence and NH₃ by acid traps.

Results

The NH₃ and NO emissions was higher in mixed RC than control and WW treatment. The N₂O emission was many-fold higher with mixed than layered distribution, but only with high soil NO₃⁻ availability and high soil moisture. Emissions of N₂O from WW were an order of magnitude lower compared to RC, and decomposition was slower. Both batch and continuous-flow incubations resulted in similar emissions. Disregarding the extreme emissions in the high WFPS and NO₃⁻ treatment, the N₂O emission factors averaged 0.3 and 0.6% of residue N for WW and RC, respectively.

Conclusion

Residue decomposition was enhanced by mixing, and N₂O emissions by higher soil water and NO₃⁻ content. The results show the importance of residue distribution and soil condition on estimating N₂O emission factors for crops.

中文翻译：

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红三叶草和冬小麦残留物的一氧化二氮排放取决于分布、土壤氮可用性和水分含量的相互作用

目标

在 43 天的实验室孵化 (15 °C) 中，研究了残留物类型和分布、土壤水分和 NO ₃ ^-可用性对 N ₂ O、CO ₂以及某些处理 NO 和 NH ₃排放的影响。

方法

考虑了两种作物残留物（红三叶草，RC 和冬小麦，WW），它们要么与表土混合，作为土壤中的离散层放置，要么不添加。土壤 NO ₃ ^-处于环境水平或增加。水填充孔隙空间 (WFPS) 调整为 40% 或 60%。使用手动取样和气相色谱分析所有处理的矿物N、N ₂ O和CO ₂。通过激光光谱法对 N ₂ O 和 CO ₂的连续流动法、光致发光法分析 NO 和酸阱法分析 NH ₃对选定的处理进行分析。

结果

NH ₃和NO 排放在混合RC 中高于对照和WW 处理。混合分布比分层分布的 N ₂ O 排放量高许多倍，但仅在土壤 NO ₃ ^-可用性高和土壤水分高的情况下。WW的 N ₂ O排放量比 RC 低一个数量级，分解速度更慢。分批和连续流孵化都导致类似的排放。不考虑高 WFPS 和 NO ₃ ^-处理中的极端排放，N ₂ O 排放因子平均分别为 WW 和 RC 残留 N 的 0.3% 和 0.6%。

结论

混合可促进残留物分解，较高的土壤水和 NO ₃ ^-含量会导致 N ₂ O 排放。结果表明残留物分布和土壤条件对估计作物的N ₂ O 排放因子的重要性。