Abstract: By using static chamber/gas chromatograph techniques, the N₂O emission from rice-rapeseed rotation system in Chengdu Plain of Sichuan Basin was measured from June 2005 to June 2006, with its characteristics and affecting factors investigated. The results showed that the totalemission of N₂O in a rotation cycle was (8.3±2.8) kg·hm^-2·a^-1, and the emission in rice season, rapeseed season and fallow season accounted for 30%, 65%, and 5% of the total, respectively. In rice season, the mean N₂O flux was higher during alternative drainage and irrigation than during continuous flooding and drainage, and was roughly the same during continuous flooding and drainage. N application was the main driving factor for the appearance of N₂O emission peak, and the lower moisture content in surface soil layer in rapeseed season and fallow season was the main cause inducing soil N₂O absorption. Soil moisture, soil temperature, N application, and crop involvement affected the N₂O emission to various extents, and soil moisture was the key factor affecting the N₂O emission. To avoid the high frequency of dry and wet alternation in rice season or to regulate soil moisture content to a level of 50%-70% WFPS (percentage of water-filled pore space) in rapeseed season and fallow season could effectively decrease the N₂O emission from the rice-rapeseed rotation system.

Key words: Nanchangshan Island, carbon storage, Pinus thunbergii,  Robinia pseudoacacia.