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Bottom ash (BA), a byproduct of coal combustion from electric power plants with a porous surface texture and high pH, may influence the physical and chemical properties of upland arable soil associated with nitrous oxide (N2O) emission from upland soil. This study evaluated the use of BA in mitigating N2O emissions from upland arable soil and increasing the crop yield. In a field experiment, N2O emitted from the soil was monitored weekly in a closed chamber over a 2-year period (2018–2019). BA was applied to upland soil at the rates of 0, 200, and 400 Mg·ha−1. Cumulative N2O emission significantly decreased with increasing BA application rate; it decreased by 55% with a BA application rate of 400 Mg·ha−1 compared with the control. Yield-scaled N2O emission decreased with increasing BA application rates of up to 200 Mg·ha−1. Water-filled pore spaces (WFPS) were 70.2%, 52.9%, and 45.3% at the rates of 0, 200, and 400 Mg·ha−1, respectively, during the growing season. For economic viability and environmental conservation, we suggest that BA application at a rate of 200 Mg·ha−1 reduces N2O emissions per unit of crop production.

N stabilizers such as urease and nitrification inhibitors are potential tools for mitigating N 2 O emissions and improving maize yield. However, the efficacy of N stabilizers is inconsistent across a broad range of agroecosystems. To enable the large-scale use of N stabilizers for sustainable agricultural development, it is necessary to identify the benefits of N stabilizers and the driving factors that regulate their efficiency. Here, we evaluated the efficiencies of 3,4-dimethylpyrazole phosphate (DMPP) and N-(n-butyl) thiophosphoric triamide (NBPT) in four typical ecological sites with contrasting climatic and soil conditions in the maize production area of China (Gongzhuling, Wuqiao, Xinxiang, and Wenzhou). Disparate ecological sites significantly influenced the N 2 O emissions (0.2–19.0 kg N 2 O-N ha−1) and maize yields (7.5–13.9 Mt ha−1). Also, N stabilizers reduced N 2 O emissions by 1.3–93.9 % across the four sites. Compared to NBPT, DMPP showed higher efficiency, but the joint inhibitor (NBPT+DMPP) had non-significant effects compared to DMPP. Although N stabilizers did not significantly increase maize yield, they reduced yield-scaled N 2 O emissions (YSNEs) by 3.1–83.4 % (p < 0.05) across study sites. Hotspots of N 2 O emission occurred within two weeks after N fertilization, and the mitigation of N stabilizers on N 2 O emissions was strongly reduced over time. This implies the degradation velocity of N stabilizers was critical for emissions mitigation efficiency. Meanwhile, environmental factors obviously influenced N stabilizers efficiency. Random forest and correlation analyses indicated that soil pH and sand content showed positive correlations and high importance for the N 2 O mitigation efficiencies of N stabilizers, whereas water-filled pore space and salt content showed negative correlations and high importance. In addition, N 2 O mitigation efficiencies of different N stabilizers showed a different response to environmental changes, wherein higher environmental sensitivity and easy invalidation under unsuitable conditions were observed in NBPT than in DMPP. In conclusion, DMPP effectively mitigated YSNEs in all study sites, and its efficiency was closely regulated by soil pH, water-filled pore space, and soil texture. Therefore, amending soil quality may enhance the benefits of DMPP and might decrease future N 2 O emissions in the maize fields of China. [Display omitted] • N stabilizers reduced yield-scaled N 2 O emissions with DMPP having higher efficiency across various maize cropping system. • N stabilizers showed higher benefits with N 2 O mitigation than maize yield improvement. • Degradation velocity and environmental factors markedly effect N stabilizers efficiency. • NBPT demonstrated higher unsteadiness and environmental sensitivity than DMPP. • Soil pH and air permeability amendment might be an effective strategy for improving N stabilizer benefits. [ABSTRACT FROM AUTHOR]

Bottom ash (BA), a byproduct of coal combustion from electric power plants with a porous surface texture and high pH, may influence the physical and chemical properties of upland arable soil associated with nitrous oxide (N2O) emission from upland soil. This study evaluated the use of BA in mitigating N2O emissions from upland arable soil and increasing the crop yield. In a field experiment, N2O emitted from the soil was monitored weekly in a closed chamber over a 2-year period (2018–2019). BA was applied to upland soil at the rates of 0, 200, and 400 Mg·ha−1. Cumulative N2O emission significantly decreased with increasing BA application rate; it decreased by 55% with a BA application rate of 400 Mg·ha−1 compared with the control. Yield-scaled N2O emission decreased with increasing BA application rates of up to 200 Mg·ha−1. Water-filled pore spaces (WFPS) were 70.2%, 52.9%, and 45.3% at the rates of 0, 200, and 400 Mg·ha−1, respectively, during the growing season. For economic viability and environmental conservation, we suggest that BA application at a rate of 200 Mg·ha−1 reduces N2O emissions per unit of crop production. [ABSTRACT FROM AUTHOR]