DNDC模型对川中丘陵区稻田CH_4、N_2O排放的模拟对比分析

利用IKONOS高分辨率（1m）卫星遥感图,进行典型抽样和地形→土地利用→土地覆盖→综合信息提取的方法,选定了代表川中丘陵区类特征的四川省金堂县为研究区域,通过对研究区域中不同固定耕作制度下代表性田块的选取,于2005年5月—2006年5月对田块管理者进行作物田间管理、作物产出等农业生产实际情况调查和分析,进行土壤理化性状、水样的测定,并结合当地的气象资料,利用DNDC模型模拟川中丘陵区不同耕作制度下稻田温室气体的排放情况。结果表明：冬水田-水稻田（PF）水稻生长期CH4排放通量为2.24 kg.hm-2.d-1,占年排放量的80.73%;水稻生长期和冬闲期N2O通量分别为0.033和0.003 6 kg.hm-2.d-1,水稻生长期排放量为4.28 kg.hm-2,占年总排放量的83.59%。CH4和N2O排放量在水稻整个生季节存在明显的互为消长关系。油菜-小麦田（RR）水稻生长期CH4排放通量为1.16 kg.hm-2.d-1,是休闲期的20.71倍,水稻生长期CH4排放量占年排放量的90.48%;水稻生长期和非水稻生长期N2O排放通量分别为0.070和0.027 kg.hm-2.d-1,水稻生长期N2O排放量为8.01 kg.hm-2,占年排放量的54.19%。小麦-水稻田（RW）水稻生长期CH4排放通量为1.24 kg.hm-2.d-1,是休闲期的21.02倍。水稻生长期CH4排放量占年排放量的89.75%;水稻生长期和非水稻生长期N2O排放通量分别为0.089和0.030 kg.hm-2.d-1,水稻生长期N2O排放量为9.61 kg.hm-2,占年排放量的55.23%。PF年CH4排放量是RR和RW的近3倍,且少一季作物产量,应尽量将冬水田改为两季田。

Research of tillage-cropping systems on CH_4 and N_2O emission from permanently flooded rice fields in a central Sichuan hilly area of southwest China

Used the high resolution（1 m） IKONOS satellite,selected representative of the middle Jintang hilly area feature as the study area.Researched of CH4 and N2O emissions from three kinds of paddy-rice fields-permanently flooded paddy fields（PF）,rapeseed-paddy rice fields（RR） and winter wheat-paddy rice fields（RW） from May 2005 to May 2006.Had some detailed farmer investigations,include crop type,tillage,fertilizer,manure type,irrigation,output.And determined and statisticsed soil pH,N con-centration in rainfall,meteorological data and so on.The results show that： The average CH4 fluxes from a permanently flooded rice field with a single middle rice crop and flooded with PF were 2.24 kg·hm-2·d-1 and 0.512 kg·hm-2·d-1 during rice-growing and non-rice growing periods,respectively.The annual CH4 emission was mainly occurred in the rice growing period,being only 29.27 % of the total annual CH4 flux emitted from the non-rice growing period,though the latter occupied two thirds of a year.The annual average flux of nitrous oxide was 0.014 kg·hm-2·d-1.N2O emission also intensive in the rice growing period.However,being only 16.41 % of total annual N2O flux emitted from the non-rice growing period.There was a clear trade-off between CH4 and N2O emis-sion in paddy fields during the growth period of paddy-rice.CH4 emission flux in rice growth stage of RR was 1.16 kg·hm-2·d-1,it was 20.71 times of leisure period.CH4 emissions of rice growth stage account for the total emissions was 90.48%.N2O emission flux in rice growth stage and leisure period of RR were 0.070 and 0.027 kg·hm-2·d-1,respectively.N2O emissions of rice growth stage account for the total emissions was 54.19%.CH4 emission flux in rice growth stage of RW was 1.24 kg·hm-2·d-1,it was 21.02 times of leisure period.CH4 emission of rice growth stage account for the total emissions of RW was 89.75%.N2O emission flux in rice growth stage and leisure period of RW were 0.089 and 0.030 kg·hm-2·d-1,respectively.N2O emissions of rice growth stage account for the total emissions was 55.23%.CH4 emissions of PF was nearly 3 times of RR and RW,and less one season of crop yields.Should as far as possible to change PF to RR and RW.