不同施肥处理对红壤晚稻田CH_4排放的影响

选取不同施肥处理的双季稻田为研究对象,采用静态箱-气相色谱法对晚稻田CH4排放通量进行观测。结果表明,与不施肥对照(T1)相比,各施肥处理CH4排放通量均有不同程度增加。其中秸秆还田+化肥处理(T5)CH4平均排放通量为9.96mg.m-2.h-1,比增氮磷施肥处理(T4)和对照分别增加26.1%和120.0%;平衡施肥处理(T2)和减氮磷施肥处理(T3)CH4平均排放通量比对照增加20%左右。说明施化肥可能提高水稻植株运输能力,进而增加CH4排放,但并未发现施化肥处理(T1、T2、T3和T4)之间CH4排放存在显著差异。同时对相关环境因素的分析表明,各处理CH4排放通量与土壤5cm深处温度间存在指数函数关系,并与田间水层厚度呈正相关关系(P<0.05)。综合考虑温室效应和稻谷产量,认为T2为推荐施肥方式,即N、P2O5和K2O施用量分别为180、90和135kg.hm-2,在插秧前1d施入占总N量70%的碳铵和全部磷肥、钾肥(过磷酸钙和氯化钾)作为基肥,并在分蘖期(2008年7月19日)追施占总N量30%的尿素。

CH_4 Emission From Late Rice Field of Red Clay Soil Under Different Fertilization Treatments

Methane emission fluxes from late rice fields under different fertilization treatments were studied, using the static chamber-gns chromatograph techniques. Results show that compared to Treatment 1 (T1, no fertilization), all the other fertilization treatments increased methane emission. The average methane flux from Treatment 5 (T5, straw incorporation) and Treatment 4 (T4, increased nitrogen and phosphate) was 9. 96 and 7.90 mg·m-2·h~(-1), respectively. Treat ment 2 (T2, balanced fertilization) and Treatment 3 (T3, decreased nitrogen and phosphate) were just approximately 20% more than Treatment 1. In terms of accumulated seasonal methane emission, the treatments followed an decreasing sequence: TS>T4>T2>T3>T1, but no significant difference (P>0.05) was observed between T1, T2, T3 and T4. According to the analysis of related environmental factors, methane emission fluxes had an exponential function relationship with soil temperature at 5 em depth, and had a positive correlation with thickness of the water layer (P<0. 05). T2 was a fertilization model recommended for the local region after comprehensive consideration of the greenhouse effect and rice yield. Considering global warming potentials of CH_4 and rice yield, T2 was a recommended fertilization method under the local condition. Total fertilizer application of N, P2O5 and K2O was 180, 90 and 135 kg· hm~(-2), respectively. Ammonium bicarbonate, with a split 70% of designed N mixed with total P and K_2O (calcium superphesphate and potassium chloride) was broadcasted on the field before transplanting as basal fertilizer, and urea was topdressed with 30% of total N at the fillering stage.