适宜节水灌溉模式抑制寒地稻田N_2O排放增加水稻产量

2014年在大田试验条件下,设置控制灌溉、间歇灌溉、浅湿灌溉及淹灌4种水分管理模式,采用静态暗箱-气相色谱法田间观测寒地水稻生长季N2O排放特征,研究不同灌溉模式对寒地稻田N2O排放的影响及N2O排放对土壤环境要素的响应,同时测定水稻产量,以期为寒地稻田N2O排放特征研究提供对策。结果表明:不同灌溉模式下N2O排放的高峰均出现在水分交替频繁阶段,水稻生育阶段前期,各处理N2O排放都处于较低水平,泡田期几乎无N2O排放。与淹灌相比,间歇灌溉使N2O排放总量增加47.3%,控制灌溉和浅湿灌溉使N2O排放总量减少40.7%和39.6%。寒地稻田N2O排放通量与土壤硝态氮含量关系密切,与土壤10 cm温度显著相关(P0.05)。水稻生长期间各处理N2O排放顺序间歇灌溉淹灌,二者均显著高于浅湿灌溉和控制灌溉(P0.05)。各处理水稻产量以浅湿灌溉最低、其他方式差异不显著。可见,间歇灌溉有助于提高水稻产量,但会促进稻田N2O的排放。在综合考虑水稻产量及稻田温室效应的需求下,控制灌溉为最佳灌溉方式,应予以高度重视。该研究可为黑龙江寒地稻作区选择节水减排模式提供科学支撑。

Optimal water-saving irrigation mode reducing N2O emission from rice paddy field in cold region and increasing rice yield

Abstract: Greenhouse gas emissions from paddy field in China have aroused widespread attention. Northeast China is the most important marketable grain base in China, and the paddy fields acreage of northeast China is increasing rapidly in nearly a decade. It has only scattered reports in regard to paddy greenhouse gas emissions in the northeast cold region. The winter of northeast is very cold and long, and organic matter of farmland soil is relatively high. Nitrous oxide (N2O) emissions from fields in cold region of northeast China may play an role in climate change. In this study, a field experiment was conducted to investigate the N2O emissions from rice paddy field in cold region under different irrigation modes and its response to environmental factors. The experiment was set up in Rice Irrigation Experimental Center of Heilongjiang located in Heping town of Qing'an county in 2014 with four treatments including control irrigation, wet irrigation, intermittent irrigation and flood irrigation. The For all the treatments, drainage and drying were conducted in the lateral tillering stage and yellow ripe stage. In addition, under the control irrigation system, the soil water content was controlled at 0.7 or 0.8 times of saturated moisture content except for seeding establishment when water layer was 0-30 mm; Under the intermittent irrigation system, water layer was arranged at 0-30 or 0-40 mm for stages other than the lateral tillering stage and yellow ripe stage; Under the wet irrigation system, water layer was arranged at 0-20 or 0-30 mm for stages other than the lateral tillering stage and yellow ripe stage; Under the flood irrigation, most of stages had water layer of 0-40 mm. Each treatment was repeated three times. During the experiment, the N2O emission was measured at 10:00-14:00 using the method of static chamber-gas chromatographic techniques. Additionally, rice yield was determined at harvest. The results showed that the N2O emissions fluxes had same trend in the seasonal variation under different treatments. The peak of emissions appeared in the stage when water alteration was frequent. The N2O emission was low in the early stage of rice growth and small amounts of N2O emissions occurred in steeping field stage. Compare to flood irrigation, the total amount of N2O emissions under intermittent irrigation increased by 47.3%, but that of control and wet irrigation treatments reduced by 40.7% and 39.6%. The N2O emission flux from cold rice paddies was closely related to soil NO3-N content and soil 10-cm temperature (P<0.05). The N2O emission from rice yield would increase with soil temperature and NO3-N content. For rice yield, the treatment of wet irrigation was worse than the others and the other treatments had no significant difference. The N2O emissions per unit yield of control and wet irrigation were 40% and 30% lower than the flood irrigation. However, the rice yield of control irrigation treatment was significantly higher than wet irrigation. Therefore, the control irrigation was best irrigation mode to increase rice yield and reduce N2O emission among the four treatments. It should be heavily emphasized in future in the cold regions of China. The results can provide valuable information for selection of water-saving irrigation method in Heilongjiang cold region.