| The increase of greenhouse gases in the atmosphere is the main cause of global warming,and agricultural soil is an important source of greenhouse gas emissions.With the increasing area of greenhouse vegetable fields in recent years,scientific irrigation and fertilization management of greenhouse vegetable fields is particularly important.The greenhouse vegetable field has the characteristics of large fertilizer application,frequent irrigation and fertilization in the long run,which determines that the vegetable field may be an important source of greenhouse gases in agricultural soil.Therefore,more and more attention has been paid to the greenhouse gas emissions from greenhouse soils and their influencing factors.The study was based on the tomato field experiment with different irrigation regimes and nitrogen fertilizer rates for five consecutive years in greenhouse.The greenhouse gas?N2O,CO2,CH4?emission characteristics were studied by static chamber gas chromatography and its influencing factors were analyzed in greenhouse.The effects of different irrigation regimes?W1-25k Pa,W2-35k Pa,W3-45k Pa,W4-55k Pa?and nitrogen fertilizer rates(N0-0 kg·hm-2,N1-75kg·hm-2,N2-300 kg·hm-2,N3-525 kg·hm-2)on soil physical and chemical properties and the relationship between soil physical and chemical properties and greenhouse gases?N2O,CO2,CH4?were explored,and which could provide data support and theoretical basis for greenhouse gas mitigation and irrigation and fertilization management in greenhouse.The main findings are as follows:?1?The N2O emission fluxes indicated a fluctuated change under different irrigation regimes,and the cumulative N2O emission was W1>W4>W2>W3.The CO2emission fluxes decreased with the increase of irrigation regimes,and the cumulative CO2 emission was W1>W3>W4>W2.The highest tomato yield was 57.84 t·hm-2 under W2 level,and its global warming potential and greenhouse gas emission intensity were the lowest.There were negative emissions of soil CH4 flux,the variation of CH4 flux in W2 was larger and ranged from-54.61?66.47(?g C m-2 h-1).The N2O emission fluxes of different irrigation regimes were very significantly positive correlation with NO2--N,NH4+-N,WFPS and pH?p<0.01?,and were significantly negative correlation with temperature.The CO2 emission fluxes was a significantly positive correlation with NO3--N,TSN?p<0.05?,and a significant negative correlation with SON?p<0.05?.The soil CH4 emission flux was very significantly negative correlation with Eh?p<0.01?.?2?The N2O emission fluxes increased with the increase of nitrogen fertilizer rates,and its cumulative emission was N3>N2>N1>N0.The order of cumulative CO2 emission was N0>N3>N2>N1.CH4 showed low and negative values throughout the tomato growth period,and showed a weak sink of CH4.Except for the treatment of no nitrogen fertilizer,the tomato yield decreased with the increase of nitrogen rates,global warming potentials and greenhouse gas emissions intensity increased with the increase of nitrogen rates.The N2O emission fluxes were very significantly positive correlation with NO2--N,NH4+-N,WFPS and pH?p<0.01?for different nitrogen rate treatments,and were very significantly negative correlation with temperature?p<0.01?.The CO2 emission fluxes were very significantly negatively correlation with NO3--N,TSN?p<0.01?,and were significantly negatively correlation with Eh and EC?p<0.05?.Considering the greenhouse effect and tomato yield,the recommended irrigation regime of 35k Pa and the nitrogenfertilizer rate of 75kg·hm-2 could increase tomato yield,effectively reducing global warming potentials and greenhouse gas emission intensity,and which were the best treatments in this research. |
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