Comparative Study Of Qinghai-Tibet Plateau And Loess Plateau Soil Nitrogen Mineralization Process Response To Temperatures Change

One of the characteristics of global climate change is the temperature increase.Temperature increase not only will be changed the farmland ecosystem carbon, nitrogen input and accumulation, but also significantly affect soil nitrogen transformation, especially soil organic nitrogen mineralization, and then changing the soil nitrogen supply. The thesis focuses on this issue, use intermittent long-term leaching aerobic incubation method, collected 11 major arable soil species from Qinghai-Tibet Plateau and also collected 11 species in Loess Plateau. Culture these soils on constant temperature incubator 210 days in 15℃, 25℃, 35℃and 45℃. On the basis of study the temperature effect on soil organic nitrogen mineralization, Focus on the Qinghai-Tibet Plateau and the Loess Plateau, soil nitrogen mineralization to temperature differences in the response.a) Explained the differences between Qinghai-Tibet Plateau and the Loess Plateau soil leaching aerobic incubation of soil organic nitrogen mineralization and mineralization parameters. The results show that aerobic incubation of soil leaching and determination of mineral nitrogen (Nm) and organic nitrogen mineralization potential (N0) of the Qinghai-Tibet Plateau under different temperature were significantly higher than that measured for soil culture results (p <0.05): We can find from the average of the tested soil the determination of the Qinghai-Tibetan Plateau soil cultivation N0 and Nm range is 42.18 149.44mg.kg-1 and 46.81 156.49mg.kg-1, while using the Loess Plateau soil analysis results varied from 33.16 81.68 mg.kg-1 and 34.70 84.78mg.kg-1, those shown that the easier mineralization nitrogen soil in Qinghai-Tibet Plateau's content is richer than the Loess Plateau.b) When the temperature increased from 15℃to 35℃, nitrate produced by mineralization of organic nitrogen and a maximal increase slope of organic nitrogen mineralization accumulation was significantly increased with culture temperature, but when the temperature is above 35℃this effect was reduced, the Qinghai-Tibet Plateau's changed was larger than the Loess Plateau. Mineralization of ammonium accumulation in the 15³5℃on the relatively weak response to temperature change. At 35℃to 45℃on the mineralization between the cumulative amount of ammonium increased significantly with increasing temperature. And Qinghai-Tibet Plateau's rate of increase is greater than the Loess Plateau.c) The effect of temperature on organic nitrogen mineralization net rate of soil samples collected from Tibetan Plateau was larger than that of Loess Plateau.When the culture temperature is less than 35℃, Qinghai-Tibet Plateau and the Loess Plateau mineralization rates of soil organic nitrogen increased with increasing cultivation temperature, but when the temperature exceed 35℃, the organic nitrogen mineralization rate was decreased with temperature increased and the differences were significant.d) Q₁₀ values of the temperature coefficient varies with temperature, Qinghai-Tibet Plateau between 0.74 and 2.09, Loess Plateau between 0.77 and 1.83. Qinghai-Tibet Plateau and the Loess Plateau, the Q₁₀ values has significantly different between 15 25℃and 25 35℃with 35 45℃.Comprehensive analysis, Qinghai-Tibet Plateau mineralization of soil organic nitrogen is more sensitive response to temperature than the soil on the Loess Plateau. Initially proved this scientific hypothesis: Qinghai-Tibet Plateau soil nitrogen mineralization responses to temperature change is more significant than the Loess Plateau.