摘要:农业氨减排是雾霾治理最经济有效的方法，而农田肥料施用造成的氨排放是农业氨排放的重要部分。本研究旨在探讨冬小麦-夏玉米复种体系下土壤氨排放对秸秆还田的响应，为减少农业氨排放和控制雾霾提供理论依据。本试验于2018年6月—2019年6月在陕西关中杨凌地区，对土壤氨排放、0~40 cm土壤无机氮以及产量进行了测定分析。试验采用双因素裂区设计，主区为秸秆还田方式，设不还田（S0）、半量还田（S0.5）和全量还田（S1）3个水平；副区为施肥，设不施肥（F0）、减量施肥（F0.8）、常规施肥（F1）3个水平。结果表明：秸秆还田与施肥及两者互作对夏玉米季土壤氨累积排放量（C）有显著影响。秸秆还田对冬小麦季土壤氨累积排放量无显著影响。整个麦玉复种体系的氨累积排放量为1.31~19.26 kg·hm-2，占施肥量的2.17%~4.69%，各处理之间表现为：S0F1 > S0.5F1 > S1F1 > S0F0.8 > S0.5F0.8 > S1F0.8 > S1F0 > S0.5F0 > S0F0。在不施肥情况下，秸秆还田能增加土壤氨累积排放量，但秸秆还田配施氮肥较不还田处理显著减少土壤氨累积排放量和氨损失率，秸秆全量还田和半量还田之间的氨排放无明显差异。其中S1F0.8和S0.5F0.8处理在整个复种体系中减排效果最为显著，分别较S0F0.8处理（11.62 kg·hm-2）减排38.64%和37.35%。相比于只施氮肥，秸秆还田配施氮肥能显著减少土壤中无机氮，显著提高夏玉米产量6.23%~20.20%，冬小麦产量16.60%~28.17%。通过PCA分析发现，S1F0.8和S0.5F0.8处理是减排增产的最优组合。综合考虑土壤氨排放和作物产量，长期秸秆还田配减量施肥处理，能在保证作物高产的基础上减少土壤氨排放，可在关中地区实施。
关键词:麦玉复种/
氨排放/
产量/
减量施氮/
秸秆还田
Abstract:Reducing agricultural ammonia emissions is considered the most economical and effective method to mitigate haze pollution. Notably, ammonia emissions caused by fertilizer application in agricultural practices are a significant contributor to atmospheric ammonia. In this context, this study aimed to explore the effect of straw returning on ammonia emissions from soil using a winter wheat-summer maize multiple cropping system to provide a theoretical basis for reducing agricultural ammonia emissions to control haze pollution. The study was conducted from June 2018 to June 2019, in the Shaanxi Guanzhong region, China. The experiment used a random block design encompassing different straw returning treatments—no straw returning (S0), half straw returning (S0.5), and full straw returning (S1), as main treatments; and different fertilizer applications—no fertilization (F0), 20% fertilizer reduction (F0.8), and conventional fertilization (F1), as sub-treatments. Soil ammonia emissions, inorganic N (in 0-40 cm of soil), and crop yield, were measured for all treatments. The results showed that straw returning and fertilization, and the interaction between the two, had a significant effect on cumulative ammonia emissions (C) in the summer maize season. Conversely, straw returning had no significant effect on C in the winter wheat season. The C of the entire wheat-maize multiple cropping system was 1.31-19.26 kg·hm-2, accounting for 2.17%-4.69% of the fertilizer application. Performance among the treatments was as follows: S0F1 > S0.5F1 > S1F1 > S0F0.8 > S0.5F0.8 > S1F0.8 > S1F0 > S0.5F0 > S0F0. Notably, straw returning showed an increase in C without fertilization. However, when compared with no straw returning, straw returning combined with fertilization significantly reduced the C and the amount of ammonia loss that occurred. There was no significant difference in ammonia emissions between full and half straw return treatments. Notably, the ammonia emission reduction effect of S1F0.8 and S0.5F0.8 treatments were the most significant for the study, reducing 38.64% and 37.35% from S0F0.8 treatment, respectively. Straw returning combined with N fertilizer also demonstrated a significant reduction in NO3--N and NH4+-N in soil, while increasing the yield of summer maize by 6.23%-20.20%, and winter wheat by 16.60%-28.17%. Further to this, PCA analysis indicated that S0.5F0.8 and S1F0.8 treatments were the optimal treatment combinations of those tested for the study, providing a balance between ammonia emission reduction and increased crop production. Therefore, our findings indicate that long-term straw returning combined with fertilizer reduction could improve crop yield as well as reduce soil ammonia emissions, suggesting an agricultural practice that can assist in the reduction of agricultural ammonia emissions, and thus help mitigate haze pollution in the Guanzhong region.
Key words:Wheat-maize multiple cropping system/
Ammonia emission/
Yield/
Nitrogen fertilizer reduction/
Straw returning
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