| Global temperature warming caused by greenhouse effects was one of the most important environment problems that human being concerned now. Soil was the important source of atmosphere CO2, and soil respiration was also an important index of soil fertility and soil biological activity. This article was dear with soil air CO2 concentrations and soil CO2 evolution of Lou soil with different fertilizations in agriculture ecosystems in Loess plateau in Northwest China by the method of fixed position monitoring in the field and incubation experiment in laboratory, during the studying kinetics and thermodynamics theory and method ware used to describing soil respiration and soil CO2 emission. The soil CCh evolution amount in one year was determined through the monitoring, and the effect of soil air CO2 concentration on crop growth was paramilitary studied in this article, the object of this article was to obtaining useful information for determine and regulating the CO2 contribution of soil to atmospheres, and protecting the atmosphere environment from pollution and keeping the agriculture sustained development. The results was as follows:The CO2 concentration in the soil air was observed to vary over a wide range with the daytime, the season and within the soil profile. The generally patterns of soil air CCh dynamics in one day was similar to the patterns of temperature dynamics, but it 'was delayed for about 2 hours. The seasonal patterns of soil air CO2 dynamics were very complexes, the graphs shows three peak, two low and one platform. Within the soil profile the concentration of CO2 was generally observed to be lower at surface layer and higher at deeper layer. Soil water content, temperature and fertilization all obviously influenced soil air CCh concentration and its changes within soil profile and with times, and obviously interactive effects of these three factors on soil air CCh dynamics were observed. Therelationship of soil air CO2 concentration with soil water content or temperature was described by quadratic equation very well. There were strong correlations of soil air CO2 concentration with temperature, and correlations with soil water content were weak. The effects of fertilization on soil air CO2 concentration were different wirh season and withinlayer. Soil air CO2 concentration could be calculated by quadratic equation using 10cm soil temperature The annual average soil air CO2 concentration of soils with different fertilizations ( CK> NP> straw℃NP and farmyard manure℃NP) was 0.5319%, 0.6043%, 0.5393% 和0.5935% separately.There was obviously diurnal and seasonal variation in Soil CO2 efflux rate in farmland Lou soil. The diurnal variation pattern was similar to that of temperature, and was delayed for about 2 hours. The seasonal variation pattern that was controlled by temperature, water content and disastrous climate event was very complexes, and soil CO2 efflux rate in summer was as 4.37-7.42 times as that in winter. Soil CO2 efflux rate was influenced significantly by temperature, soil water content and fertilization. The relationship of soil CO2 efflux rate with soil water content or temperature was well described by a simple power function or quadratic equation. Regressed separately, strong relationship between soil C02 efflux rate and temperature accounted for approximately 27-46% of evolution variability, while very weak relationship between soil CO2 efflux rate and soil water content accounted for approximately <10% of the variability. Soil CO2 eftlux rate and amount was increased by fertilization, and was increased more in soils with chemical fertilizer and straw or manual combining applied. The annual soil CO2 efflux of soils with different fertilization treatment( CK, NP, straw℃NP and farmyard manure℃NP)was 13569,15631,17638 and 16441 kgCO2hm-2y-1 separately,The results form short-term incubation experiment (incubated 14 days in 10℃-30℃) showed that (1) Soil respiration rate and amount of CO2 emission were increased as temperature raising, and increased as soil water c...
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