Experiment For Water-Saving And Greenhouse Effect Of Irrigation Mode In Cold Rice Area

As one of the major food crops in the world, rice production faces two problems:shortage of water resources and increasing greenhouse gas emission. It is focus for both academic research and social communities concern.It chose rice crop in cold area to research on the water-saving effect and greenhouse effect of different irrigation modes by using therorical analysises、barrel experiments、field experiments and comprehensive evaluation.Based on field experiment and barrel experiment, it comprehensively analyzed the rice biomass、utilization of precipitation、WUE and irrigation water use efficiency under control irrigation、wet irrigation、intermittent irrigation and flood irrigation. It studied CH4and N2O emission regularity and discussed some factors affecting CH4and N2O emission, and assessed greenhouse effect of different irrigation modes. It used PPC based on RAGA to evaluate the different irrigation modes to further choose environmental-friendly water-saving technology which fits to rice in cold area.The main conclusions are following:1.Using same amount of water, rice with control irrigation mode can get much higher yield, flood irrigation lowest. Under control irrigation mode, irrigation water use efficiency is2.59kg·m-, water use efficiency is1.55kg·m-3; under intermittent irrigation mode, irrigation water use efficiency is2.22kg·m-3, water use efficiency is1.40kg·m-3; under wet irrigation mode, irrigation water use efficiency is1.93kg·m-3, water use efficiency is1.22kg·m-3; under flood irrigation mode, irrigation water use efficiency is1.38kg·m-3, water use efficiency is0.97kg·m-3.2.As to as the proportion of effective rainfall in the rice consumption water, under control irrigation, it is40.05%, flood irrigation29.55%, wet irrigation36.48%, intermittent irrigation36.96%;as to as utilization of precipitation, flood irrigation mode is83.51%, control irrigation mode is72.05%, wet irrigation mode is89.32%, intermittent irrigation is76.93%. 3.In the whole growth period, under flood irrigation CH4emission amount is highest, control irrigation lowest. Under flood irrigation, CH4emission flux was2.49mg· m-2· h-1, accumulated emission was6.46g·m-2,greenhouse effect is1356.51kgCO2·ha-1; under intermittent irrigation mode, CH4emission flux was2.11mg·m-2·h-1, accumulated emission was5.47g·m-2,greenhouse effect is1149.52kgCO2·ha-1; under wet irrigation mode, CH4emission flux was1.36mg·m-2·h-1, accumulated emission was3.52g·m-2,greenhouse effect is739.18kgCO2·ha-1under control irrigation mode, CH4emission flux was0.97mg· m-2· h-1, accumulated emission was2.51g·m-2,greenhouse effect is526.49kgCO2·ha-1.4.In the whole growth period, under control irrigation N2O emission amount is highest, flood irrigation lowest. Under control irrigation, N2O emission flux was29.71μg· m-2· h-1, accumulated emission was77.01mg·m-2,greenhouse effect is238.72kgCO2·ha-1; under intermittent irrigation mode, N2O emission flux was26.53μg· m-2· h-1, accumulated emission was68.47mg·m-2,greenhouse effect is213.19kgCO2·ha-1; under wet irrigation mode, N2O emission flux was26.14μg· m-2· h-1, accumulated emission was67.76mg·m-2,greenhouse effect is210.16kgCO2·ha-1; under flood irrigation mode, N2O emission flux was14.23μg·m-2· h-1, accumulated emission was36.88mg·m-2,greenhouse effect is114.32kgCO2·ha-1.5.Except for wet irrigation mode, under the other irrigation modes, CH4emission flux peak appeared in tillering stage, under wet irrigation mode, CH4emission flux peak appeared in jointing-booting stage; N2O emission had obvious two peak characteristic, the peak emission appeared in tillering stage and ripening stage; compared with flood irrigation mode, control irrigation、wet irrigation and intermittent irrigation can suppress greenhouse gas emission and reduce the total greenhouse effect of CH4and N2O.The innovation points are following:1.Two methods were used to calculate rainfall use utilization efficiency which refers to experiment and theory calculation;2.It did greenhouse gases emission experiments for paddy rice in cold area and gave the greenhouse gases emission data which filled in the blanks of greenhouse gases emission data for paddy rice in cold area.