| N2O, as a trace gas in the atmosphere, could cause greenhouse effect and damage the ozone lay in stratosphere. The main source of N2O is from soil, with a contribution rate of 70-90%. Investigation into N2O emission amount, emission mechanism and approaches to reduce the emission from farmland is of great significance for environment protection and economic growth. Fallow lands of winter wheat in the southern part of loess plateau with an annual precipitation of 632mm were selected as the study object, Field and lab experiments were carried out during two wheat growth periods to investigate the correlations between N2O emissions and its influential factors, quantitative model and energy characteristics.Through this experiment, the simulation equations of factors such as water content, heat, fertilizer and the depth of the tilled land that would influence N2O emissions flux were established, the dynamic N2O emissions equation concerning water content and temperature was also established. These equations would explain the zero influence of water and temperature on N2O emissions and provide relevant parameters. The critical soil water content and N2O emissions critical minimal and maximal temperature contributing to the zero influence on N2O emissions. It also was found that N2O emissions in deeper soil would change with the temperature. 15@ is the emission retardation temperature in deep soil layer; 20@ is the turning temperature for the increase of N2O emissions; 25癈-30癈 is the boosting range for the emission. It has proved that the period from wheat booting to blossoming is the boom period for N2O emissions. Temperature and C source matters are the key factors that would influence N2O emissions in this region. This paper also put forwards that urease activity at the soil depth of 0-20cm could be used as the biological indicator of N2O emissions in wheat field and has proved its feasibility. In addition, by using biological active energy and thermo-chemical energy parameters, the paper also discussed N2O emissions mechanism.The progress and innovative thinking are as followings:1. During the growth period of winter wheat, the N2O emission from wheat field and the fallow land is 5.22-70.92ug/m2and 4.7-60.2ug/m2, respectively N2O emission in wheat land is larger than that in the fallow land; N2O emission during the period from booting to blooming is larger than that in any other growth periods, with an average amount of 20.7-70.92ug/m2 During the two experimenting periods (2001, 2002), the emission flux of different growth stages is insignificantly correlated to the corresponding average daily temperature within ten days of each month. However, in 2001, the average emission flux is closely related to the rainfall in the corresponding ten days of each month, the correlation in 2002 is not significant. Compared with that in 2002, the rainfall in the growth periods in 2001 is smaller, but this fact did not have a significant influence on N2O emission flux, but nitration function had a significant influence on N2O emission. N2O emission flux in farmland isn't significantly related to the water content in tilled layer, theinteraction between water and heat, but apparently has liner relation with the temperature in the soil layers at the depth of 10cm and 20cm. The correlation is less significant that with fallow land. N2O emission is also positively related to the N/C ratio, this ratio is regarded to be the key factor that affects N2O emission. Increase the application of organic fertilizer and other C source substances may promote N2O emission in soil.2. The impact of soil depth to N2O emission in arid wheat field is greatly influenced by water content and the temperature conditions. When the water content in the soils is 14.5%, the sample soil depth coefficient of the average N2O emission flux (dY/dh) is the function of Y and would increase with the Y value, it has no correlation with the depth of soil; the temperature for N2O emission retardation is at 15℃, soil at the depth of 5-10cm has t...
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