农田N2O排放研究进展

农田土壤是大气中N2O的重要来源，与1990年相比，2000年我国氮肥用量升高了40％，因此，迫切需要对我国农田土壤N2O的排放通量作出新的估算。土壤理化性状的空间变异和不同生态条件下进行长期的、多点的农田N2O原位监测数据的匮乏成为提高N2O排放测定精度的制约因素。目前，航空采样法-驰豫涡动技术(微气象学方法)能够成功克服空间变异，且已经被成功应用在农业生态系统N2O排放的定量化观测上；另外Century-NGAS和DNDC模型是目前应用较广泛的机理模型，但应用不同模型所获得的N2O排放量相差较大。因此，今后农业土壤N2O排放的工作重点应集中在如何提高N2O原位观测精度，寻找合适的机理模型和提出相应的减排措施。

Emission of N2O from agricultural soils

Agricultural soils are the most important source of N2O emission. N application in China in 2000 has increased by 40% as compared with that of 1990, therefore, re-estimation of N2O emission from arable is urgently needed. Spatial variability of soil properties and short of year-round monitoring data of N2O emission under a wide range of agricultural practices have been the main barriers for improving the accuracy of N2O emission estimates. Aircraft-based relaxed eddy accumulation technique in combination with tower-based N2O flux measurements can provide valuable information for testing and improving models. N2O estimates from various models are still highly uncertain, even though process-based model such as Century-NGAS and DNDC are widely used. More efforts on improving the in situ monitoring accuracy and improving process-based models are encouraged to propose the best mitigation practices.