水稻控制灌溉下华东稻麦轮作农田N_2O排放模拟

Simulation of N_2O Emission from Rice-Wheat Rotation Field under Controlled Irrigation of Rice in Southeast China

基于田间小区试验,利用DNDC模型模拟了水稻控制灌溉下的华东稻麦轮作农田N_2O排放情况,分析了DNDC模型在该地区以及水稻控制灌溉条件下的适用性。结果表明,DNDC模型能较好地模拟控制灌溉稻田N_2O排放规律,模拟值与实测值的相关系数为0.79(n=39,p<0.001);同时能较好地模拟控制灌溉稻田N_2O排放通量与土壤水分调控及施肥的关系。但模型对土壤脱水程度的响应不够敏感,导致部分峰值出现时间稍有滞后。后茬麦田N_2O排放通量的模拟值多低于实测,模拟主峰值较实测值增大了14.96%(p<0.05),模拟次峰值比实测值减小了18.10%(p<0.05)。稻季、麦季及稻麦轮作期的N_2O排放总量的模拟值与实测值的相对误差分别为5.86%、-20.17%(p<0.05)和-4.97%,可见,DNDC模型能较好地模拟控制灌溉稻田N_2O排放总量,但明显低估了后茬冬小麦田的N_2O排放总量,稻麦轮作农田N_2O排放总量的模拟值和实测值总量相差不大。因此,DNDC模型可以用来模拟华东地区控制灌溉稻田N_2O排放,但不能准确地模拟后茬冬小麦田的N_2O排放。

Based on the field plot experiments in Southeast China, N2O emissions from the rice—wheat rotation field under controlled irrigation of rice were simulated by using the DNDC model, and the applicability of this model in the region was analyzed. The results showed that N2O fluxes from controlled irrigation rice fields were generally higher than those from the following wheat fields, and the average flux was 3.0 times of that in the following wheat fields. DNDC model successfully simulated the rules of N2O emissions from controlled irrigation rice fields, and the correlation coefficient between the simulated and measured values was 0.79 （n=39, p〈0.001）. It could also simulate the relationship between the N2O fluxes and soil moisture regulation and fertilization. But the response of the model to the extent of soil dehydration was not sensitive enough, resulting in the slight lag of some N2O peaks. Simulated N2O fluxes from the following wheat fields were usually lower than the measured values. Compared with the measured values, the simulated value of the highest peak was increased by 14.96% （p〈0.05）, and the simulated value of the smaller peak was decreased by 18.10% （p〈0.05）. The relative errors between the simulated and measured values of the cumulative N2O emission during the rice season, wheat season and rice—wheat rotation period were 5.86%, -20.17% （p〈0.05） and -4.97%, respectively. These results indicated that the DNDC model can well simulate the cumulative N2O emission from the rice fields under controlled irrigation, but the N2O emissions from the following wheat fields were significantly underestimated. The difference between the simulated and measured values of total N2O emission from rice—wheat rotation field was small. Thus, the DNDC model can be used to simulate the N2O emissions from controlled irrigation rice fields in Southeast China, but it can not accurately simulate the N2O emissions from the following wheat fields. Transactions of the Chinese Society for Agriculture Machinery （CSAM）, in charged of China Association for Science and Technology （CAST）, sponsored by CSAM and Chinese Academy of Agricultural Mechanization Science（CAAMS）, started publication in 1957. It is the earliest interdisciplinary journal in Chinese which combines agricultural and engineering. It always closely grasps the development direction of agriculture engineering disciplines and the published papers represent the highest academic level of agriculture engineering in China. Currently, nearly 8,000 papers have been already published. There are around 3,000 papers contributed to the journal each year, but only around 600 of them will be accepted. Transactions of CSAM focuses on a wide range of agricultural machinery, irrigation, electronics, robotics, agro-products engineering, biological energy, agricultural structures and environment and more. Subjects in Transactions of the CSAM have been embodied by many internationally well-known index systems, such as： EI Compendex, CA, CSA, etc.