不同氮、磷肥用量下双季稻田的CH4和N2O排放

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、...

Observation for CH4 and N2O Emissions Under Different Rates of Nitrogen and Phosphate Fertilization in Double Rice Fields

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· (m²·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). N₂O emission was very little during mid-seasonal drainage period. In contrast, N₂O emission peaks were observed in period of alternation of wetting and drying after mid-seasonal drainage in this experiment. N₂O 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 N₂O 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 N₂O 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.