Effects Of Simulated Acid Rain On Greenhouse Gases (CO2and N2O) Emissions From Farmland And Influence Mechanism

Acid rain and global warming are the most important problems in the world. And farmland ecosystem occupies an important positon in global greenhouse gas balance. In order to investigate to the effects of acid rain on emissions of respiration and N2O from soil-crop system, the experiment was carried on with winter-wheat and soybean.3blocks were arranged and there were4acid rain treatments, which were coded as C (pH=6.4), T,(pH=4.0), T2(pH=3.0) and T3(pH=2.0) in each block. Static chamber-gas chromatography method was used to analyze respiration and N2O emission. At meantime, the plant growth, plant nitrogen metaboliam index and the indicators of product N2O substrate in the soil were analyzed. It provided the scientific basis to objective evaluate the ecological effect of acid rain, as well as to estimate the effects of acid rain on the greenhouse eimission from farmland.Results showed that:Simulated acid rain did not change the seasonal pattern of respiration rate from soil-winter wheat system. T2increased the respiration significantly (p=0.046) during turning green stage. T2and T3significantly declined the respiration rate during maturation stage (p=0.020,p=0.018). T3significantly declined the cumulative amount of CO2emission (p=0.034) of the whole growth period. Simulated acid rain did not change the seasonal pattern of N2O emission from soil-winter wheat system. During the whole growth period, T3significantly declined the average N2O emission for24.75%(p=0.038). Simulated acid rain did not change the seasonal pattern of repiration from soil-soybean system. T2sinificantly declined the repiration (p=0.013) of soil-soybean system during trileaf-branching stage. During the whole growth period, T3significantly declined the average repiration rate (p=0.005) and the cumulative amount of CO2emission (p=0.006). Simulated acid rain did not change the seasonal pattern of N2O emission from soil-soybean system. T2and T3significantly increased the average N2O emission (p=0.018,p=0.003) of the whole growth period. T1significantly declined the cumulative amount of N2O emission (p=0.011) during flowering-bearing pod stage. T2and T3significantly increased the cumulative amount of N2O emission (p=0.001,p=0.003) during flowering-bearing pod stage. During the whole growth stage, T2and T3significantly increased the cumulative amount of N2O emission (p=0.013, p=0.006). The respiration and the cumulative amount of CO2emission of soil-soybean system were higher than that of soil-winter what system. But the average N2O and the cumulative amount of N2O emission of soil-soybean system were lower than that of soil-winter wheat system.It observed an obvious diuranal varation of respiration rate of soil-winter wheat system, and simulated acid rain did not change the pattern. The law of diranal varation of N2O emissions in soil-winter wheat system was performanced for the random.