| Purple soil agro-ecosystem research center (Chinese Academy of Sciences) is situated in upriver Yangtze and southwest SiChuan hilly region. Calcium purple soil is the main soil type of that region. Research on greenhouse gas emission of dry land purple soil ecosystem has significant meaning to carbon fluxes of land ecosystem. Agro-ecosystem is the most active part of human activities, therefore, research on carbon fluxes of agro-ecosystem is essential to the study of global carbon fluxes.Using static chamber and gas chromatographic techniques, both seasonal and daily change rules of greenhouse gas emission from dry land ecosystem of mid-SiChuan hilly area were carefully monitored. Furthermore, variation characteristics of greenhouse gas emission under different climate condition were studied. Environmental factors which are responsible for greenhouse gas emission were also proposed.By means of field investigation and sample analysis, both daily and seasonal variation characteristics of greenhouse gas emission from dry land ecosystem were inquired, and environmental factors' influence on various greenhouse gases was clarified. In this study, we concerned on emission fluxes and related process of greenhouse gas in dry land ecosystem of mid-SiChuan hilly area. There were four treatment schemes involved in this experiment. Scheme one, crops were fertilized and treated as conventional, respiration effects of plant, root system and soil were determined respectively. Scheme two, the control (without plant in the static chamber), respiration effects of root system and soil were determined. The third scheme was plain field, and respiration effects of soil without plant were investigated. The fourth scheme involved plants in the chamber, but without nitrogen input, by which crops' influences on greenhouse gas emission were achieved. Results showed that emission fluxes of methane, carbon dioxide, and N2O in these area presented different seasonal change and daily change. The seasonal fluxes of methane was proved to be mainly absorbing, which could be regarded as a sink on the whole. While the seasonal fluxes of CO2 and N2O were mainly emission, which could be viewed as a source. Seasonal emission rules of greenhouse gas also showed different change trend at different season of plant growth. During the growth period of wheat, seasonal emission character of greenhouse gas showed evident correlation with the growth of wheat. Whereas during the growth season of corn, its seasonal emission character of greenhouse gas had no evident relationship with the growth of corn. However, daily variation trends were basically the same. Result indicated that emission fluxes of greenhouse gas significantly varied from each other. Generally, the emission fluxes followed the order of conventional treatment>the control>plain field treatment.Through the whole growth period of wheat, emission fluxes of CO2, N2O, and CH4 varied significantly from treatment to treatment. Emission fluxes of CO2 followed the sequence of conventional treatment>the control>plain field treatment, and different growth period could also influence the emission fluxes. The average seasonal emission fluxes of conventional treatment was 329.67 mg m-2h-1, and the average seasonal emission fluxes of the control was 175.65 mg m-2h-1 while the average seasonal emission fluxes of plain field was 89.25mg m-2 h-1, and that of non-nitrogen treatment was 359.32mg m-2 h-1 During the growth period of wheat, emission fluxes of N2O fit the trend of increase by degrees, and followed the order of conventional treatment>the control>plain field treatment. The average seasonal emission fluxes of conventional treatment was 0.0275lmg m-2 h-1, and that of the control and plain field were 0.0036 mg m-2 h-1 -0.015mg m-2h-1 respectively. As for emission fluxes of CH4 its character was irregular because dry land ecosystem lack anaerobic environment, which was essential for the forming of CH4.Carbon dioxide emission fluxes of corn in mid-SiChuan hilly area was proved to be emissi...
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