摘要:在等施氮量条件下，比较有机肥与无机肥施用后旱地玉米-豇豆复种系统土壤硝化与反硝化作用、N2O排放与作物产量的变化，有助于正确认识肥料施用对N2O排放的影响，为制定大田合理的丰产减排措施提供理论依据。本研究通过田间试验，利用静态箱技术和BaPS气压过程分离技术研究了不同肥料类型处理（无机肥、有机肥、有机无机肥配施）下玉米-豇豆种植系统土壤N2O排放、硝化与反硝化作用的变化特征。结果表明：1）相对于单施无机肥或有机肥，有机无机肥配施可显著降低土壤硝化作用速率；在玉米生长季，有机无机肥配施处理平均土壤硝化作用速率分别比化肥和有机肥处理显著降低了28.74%和13.96%，豇豆生长季显著降低了24.66%和13.28%。土壤反硝化作用速率在各施肥处理间差异不显著。2）有机无机肥配施显著降低土壤N2O排放；在玉米生长季，有机无机肥配施处理分别比无机肥处理和有机肥处理显著降低33.44%和32.29%，在豇豆生长季分别显著降低27.00%和15.14%。3）相关分析表明，土壤N2O排放与硝化作用速率呈极显著相关，而与反硝化作用速率呈不显著相关。4）有机无机配施处理玉米和豇豆产量最高。因此，有机无机肥配施能有效降低玉米-豇豆系统土壤N2O排放和提高作物产量，是一项丰产低N2O排放的施肥技术，但长期有机无机肥配施对土壤N2O排放和作物产量的影响还需要进一步研究。
关键词:玉米-豇豆复种系统/
有机无机肥配施/
硝化作用/
反硝化作用/
N2O排放/
产量
Abstract:Nitrous oxide (N2O) is an important greenhouse gas that causes stratospheric ozone destruction. Application of chemical nitrogen fertilizers in upland cultivation systems is an important source of atmospheric N2O. It is important to determine the effects of nitrogen fertilization on N2O emissions in upland field in Central China where the relative researches is less conducted. In this study, soil nitrification and denitrification rates, N2O emissions and crop yields were investigated under application of organic and inorganic fertilizers with the same amounts of N in the field. Therefore in 2017, a field experiment was conducted to investigate the effects of different nitrogen fertilizer sources[inorganic nitrogen fertilizer (I), organic nitrogen fertilizer (O) and inorganic plus organic nitrogen fertilizers (I+O)] on nitrification rate, denitrification rate, N2O emission and crop yield under a maize-cowpea cropping system in Central China. Emission of N2O was measured by the static chamber approach and the rates of nitrification and denitrification measured by Barometric Process Separation (BaPS). The results showed that the rate of nitrification ranged from 130.90 μg·kg-1·h-1 to 340.37 μg·kg-1·h-1 in maize season, and from 145.11 μg·kg-1·h-1 to 348.75 μg·kg-1·h-1 in cowpea season. Application of organic nitrogen significantly affected soil nitrification rate. Compared with I and O treatments, I+O treatment significantly reduced soil nitrification rate respectively by 28.74% and 13.96% in maize season, and by 24.66% and 13.28% in cowpea season. However, no significant differences were observed in the rate of denitrification among three treatments. Nitrogen fertilization significantly enhanced N2O flux, with N2O flux peak observed immediately after nitrogen fertilizer application. The combined application of inorganic and organic nitrogen fertilizers markedly influenced N2O emission. The mean N2O flux in maize season under I+O treatment was (279.54±116.58) μg·m-2·h-1, which was 33.44% (P < 0.01) and 32.29% (P < 0.01) lower than that under I and O treatments. In cowpea season, mean flux under I+O treatment[(188.07±57.63) μg·m-2·h-1] decreased significantly by 27.00% and 15.14%, compared with that under I and O treatments. Moreover, compared with I and O treatments, I+O treatment significantly reduced cumulative N2O emission respectively by 33.51% and 32.51% in maize season, and by 25.77% and 15.04% in cowpea season. However, there were no significant differences in N2O flux and cumulative N2O emission between I and O treatments. Linear correlation analysis showed that N2O emission was closely related with nitrification rate. Yields of maize and cowpea varied among different treatments and I+O treatment had the highest yields of maize and cowpea. Yield of maize under I+O treatment was 1.71 and 1.23 times that under I and O treatments, and yield of cowpea under I+O treatment was 13.4 and 1.17 times that under I and O treatments, respectively. No significant difference was found in cowpea yield between I and O treatments. Our results suggested that combined application of organic and inorganic nitrogen fertilizers effectively reduced soil N2O emissions and increased crop yield in maize-cowpea cropping systems in Central China. The study had important implications for high-yield, low-carbon crop cultivation in China.
Key words:Maize-cowpea cropping system/
Combined application of organic and inorganic fertilizers/
Nitrification/
Denitrification/
N2O emission/
Yield
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