不同氮、磷肥用量下双季稻田的CH_4和N_2O排放

Observation for CH_4 and N_2O Emissions Under Different Rates of Nitrogen and Phosphate Fertilization in Double Rice Fields

以红壤双季稻田为研究对象,采用静态暗箱-气相色谱法对2009年水稻生长期内不施肥(CK),平衡施肥(BF)、减氮磷一(DNP1)、减氮磷二(DNP2)和增氮磷(INP)等5个处理的CH4和N2O排放通量以及环境因素进行观测.结果表明,早稻生长期间BF、DNP1、DNP2和INP的CH4平均排放通量为4.57、5.42、4.70和4.65 mg.(m2.h)-1,较CK分别增加39%、49%、41%和40%;晚稻生长期间CH4排放量普遍高于早稻排放,BF、DNP1、DNP2和INP较CK增加11%、1%、26%和-4%.与CK相比,施氮磷肥均提高早、晚稻返青期的CH4排放.早、晚稻生长期内所有施肥处理间CH4平均排放通量差异均不显著(p>0.05).双季稻田晒田期无N2 O排放峰值,而晒田后的干湿交替阶段出现较高排放.早、晚稻生长期内N2 O排放量占氮肥投入量的0.18%.环境因素分析表明,气温、土壤Eh和土壤湿度决定了稻田CH4排放的季节变化,而N2O排放与水、热等相关环境因子无相关性.CH4是早、晚稻田主要的温室气体,对二者整体温室效应的贡献约占90%,减排措施应针对CH4排放为主.综合考虑温室效应和水稻产量,当地早稻施肥量以BF为宜(N-P2O5-K2O用量150-90-90 kg.hm-2),而晚稻施肥量可以在BF(N-P2 O5-K2 O用量180-90-135 kg.hm-2)基础上少量增加氮磷用量.

Two non-CO2 greenhouse gas emissions（methane and nitrous oxide） and related environmental factors were measured within rice growing season under five treatments including non-fertilization（CK）,balanced fertilization（BF）,decreased nitrogen and phosphate 1（DNP1）,decreased nitrogen and phosphate 2（DNP2） and increased nitrogen and phosphate 1（INP） in double rice fields of red clay soil in 2009,using the method of static chamber-gas chromatograph techniques.The results showed that the average CH4 emission fluxes for treatments of BF,DNP1,DNP2 and INP were 4.57,5.42,4.70 and 4.65 mg·（m^2·h）^-1 during early rice growing period,which increased by 39%,49%,41% and 40% compared with non-fertilizer treatment,respectively.The average CH4 emission fluxes in late rice growing season was higher than preseason＇s.Compared to CK,CH4 emission increased by 11%,1%,26% and-4% in treatments of BF,DNP1,DNP2 and INP within late rice growing season.Applying nitrogen and phosphate enhanced CH4 emission in turning green period for early and late rice.No significant difference was observed between the CH4 emissions of five treatments during early and late rice growing season（p〉 0.05）.N2 O emission was very little during mid-seasonal drainage period.In contrast,N2 O emission peaks were observed in period of alternation of wetting and drying after mid-seasonal drainage in this experiment.N2 O emission was,on average,equivalent to 0.18% of the nitrogen applied in double rice growing season.Statistically,air temperature,soil Eh and soil moisture（water-filled pore space,WFPS） at 0-10cm depth significantly affected the fluctuations of the seasonal CH4 flux,but no significant correlationship has been found between N2 O flux and related environmental factors.CH4 was the dominated greenhouse gas in double rice fields which contributed approximately 90% for the integrated global warming potential of CH4 and N2 O released during the rice growing season.Therefore,the mitigation options should focus on how to reduce CH4 emission in local area.The result indicates that BF is a recommended fertilization method for early rice production,and a optimum fertilization for late season can increase rates of nitrogen and phosphate fertilizers on the basis of BF treatment slightly by considering total global warming potential and grain yield.The rates of BF treatment were 150-90-90 kg·hm^-2 N-P2O5-K2O for early rice,and 180-90-135 kg·hm^-2 N-P2O5-K2O for late rice,respectively.