Release Fluxes Of CO₂, N₂O From Rice-rape Rotation System In Chengdu Plain

Since late 70's of the 20th century, the Global Changes has brought extensive influence on the terrestrial ecosystem and social economic system. So it has brought regards by statesmen and scientists. The carbon and nitrogen cycling in terrestrial ecosystem is the hard-core of the global changes. Also it is the key to predict the content of CO₂ N₂O and other greenhouse gases in atmosphere and kown the reciprocity of the atmosphere and biosphere in the future.Based on the observation of CO₂ and N₂O emission from soil-vegetation systems in Chengdu Plain, diurnal and seasonal variation characteristics, influence factors were discussed in this paper. CO₂ and N₂O emission was measured by static chamber-gas chromatographic techniques (GC) in the plean area of Chengdu, China. The main results and conclusions were listed below:1) The CO₂ emission from soil-rice system verified remarkably daily from the minvalue 325 mg m^-2h^-1 at 3 P.M to the maxvalue 738.57 mg m^-2 h^-1 at 7 P.M. Relativity of quadric correlation was good between CO₂ emission and the depth of water. The average value of CO₂ emission was 257.61mg m^-2h^-1 And CO₂ emission from soil-rice was different following the sequences of bearing stage: jointing stage > milk stage > mature stage > heading stage > tillering stage > recovering stage. The characteristics of CO₂ emission from rice seasons was discribed as "The prophase lower, the metaphase higher, the anaphase lower" in the whole stage, And CO₂ emission fluctuated between 768.8⁹78.7mg m^-2h^-1 in the middle.2) CO₂ emission from soil-rice was the lowest in the recovering stage. The most significant relativity appeared respectively between CO₂ emission fluxes and the 5cm-deep-soil temperature, the 5cm-deep-soil temperature and surface ground temperature, the 5cm soil temperature, surface ground temperature and temperature inside the box since the tillering stage. Taken together, CO₂ emission varied with different lands which could be described as routine fertilized land > no nitrogen fertilized land >bare land. CO₂ net emission from rice-plant concentrated on the jionting stage and milk ripe stage; and it was lower in fallow stage than in recovering stage after the plant was cut.3) The daily N₂O emission from rice field fluctuated with discharge and absorption during the jointing stage. However, discharge was the main process. The change was mainly controlled by...