不同灌溉模式寒地稻田CH_4和N_2O排放特征及增温潜势分析

【目的】寻求黑龙江省寒地稻田的适宜灌溉方式。【方法】采用静态箱-气相色谱田间观测的方法,设置控制灌溉、间歇灌溉和淹水灌溉3种灌溉方式,展开了对寒地水稻生长季CH_4和N_2O排放特征及其增温潜势方面的研究。【结果】(1)稻田CH_4排放主要集中在分蘖期、拔节孕穗期和抽穗开花期。与淹水灌溉相比,控制灌溉、间歇灌溉能显著减少CH_4排放量(P<0.01),其中控制灌溉减少56.29%,间歇灌溉减少26.59%。(2)土壤干湿交替的晒田期和施加穗肥7 d后是稻田N_2O排放的主要时期,返青期有明显的负排放现象发生。施加穗肥后,控制灌溉稻田N_2O排放首先达到排放高峰,比间歇灌溉和淹水灌溉提前了6 d。控制灌溉和间歇灌溉N_2O排放量与淹水灌溉相比分别增加了55.6%和56.0%。(3)淹水灌溉稻田CH_4排放量与5 cm土壤温度显著正相关(P<0.01),控制灌溉稻田N_2O排放量与15 cm土壤温度显著正相关(P<0.01)。不同深度土壤温度、气温对间歇灌溉稻田CH_4和N_2O排放均有显著影响。淹水灌溉CH_4和N_2O排放受土壤温度影响显著,其影响大小与不同灌溉方式有关。【结论】不同灌溉模式影响了寒地稻田CH_4和N_2O排放特征,控制灌溉既降低了增温潜势又增加了籽粒产量,是一种较优的灌溉模式。

CH_4 and N_2O Emission from Paddy Field in Cold Region is Impacted by Irrigation Methods

【Objective】Microbial activities involved in biochemical reactions that emit greenhouse gases are modulated by soil moisture and the purpose of this paper is to examine how irrigations affect these biochemical processes in paddy field with a view to provide a guidance for managing paddy filed in cold region in Heilongjiang province.【Method】The field experiment compared three irrigation methods: control irrigation, intermittent irrigation and flood irrigation. In each treatment, we measured the change in CH_4 and N_2O emission, as well as their warming potential using the static chamber-gas chromatograph technique.【Result】(1)In all treatments, CH_4 emitted mainly during the tillering booting and flowering stages. Compared to flood irrigation, control and intermittent irrigation both significantly reduced CH_4 emission(P<0.01), with the control irrigation reducing by 56.29%and the intermittent irrigation by 26.59%.(2)The drying period during the dry-wet alternation and one week after the third nitrogen fertilization were the main emission period of N_2O, and there was a negative N_2O emission during the seeding establishment period. The N_2O emission in control irrigation peaked after the third nitrogen fertilization, which was six days earlier than the time it peaked under the intermittent and flood irrigation. Compared with flood irrigation, the control and intermittent irrigation increased N_2O emission by 55.6% and 56.0% respectively.(3)There was a significant correlation between CH_4 emission and 5 cm soil temperature under flooded irrigation(P<0.01), while under control irrigation the N_2O emission was significantly correlated with 15 cm soil temperature(P<0.01). Soil temperature profile and atmospheric temperature combined to significantly affect CH_4 and N_2O emission under intermittent irrigation, while CH_4 and N_2O emissions under flood irrigation was significantly regulated by soil temperature.【Conclusion】Irrigations do affect CH_4 and N_2O emission from paddy field in cold region, and our results showed that control irrigation not only reduces the warming potential but also increases grain yield.