长期秸秆还田对农田土壤水分运动与热力学函数关系初探

利用长期定位试验的土壤,研究了温度、水分、热力学函数之间的关系。结果表明,不同玉米秸秆还田土壤比较,土壤水势温度效应为高量玉米秸秆还田>低量玉米秸秆还田>单施化肥;在同一温度条件下,提高土壤水势可增加土壤非饱和导水率,呈现高量玉米秸秆还田>低量玉米秸秆还田、单施化肥;在相同的土壤含水量条件下,增加温度可提高土壤非饱和导水率,其导水率温度效应值(dk/dt)高量玉米秸秆还田<低量玉米秸秆还田和单施化肥。土壤含水量一定时,随着相对偏摩尔自由能变和相对偏摩尔焓变增大,土壤非饱和导水率也增大,并且高量玉米秸秆还田大于低量玉米秸秆还田和单化施肥,拟合得出的相对偏摩尔自由能变和相对偏摩尔焓变与土壤非饱和导水率方程,具有较好的适应性。

A Preliminary Study on Soil Water Transport and Thermodynamics in a Loess Soil with Straw Returning for Long Time

A 23 years-located field experiment of wheat-corn rotation with straw returning was employed to study soil water conductivity by soil water potential under different temperature. The results showed that in the different treatments, effect of temperature on soil water potential was at the order of soil with high rate corn straw>soil with low rate corn straw>soil with only chemical fertilizer. At the same temperature condition, increase in water potential resulted in rising of soil water unsaturated flow rate, which was affected by different treatment with the order of soil with high rate corn straw>soil with low rate corn straw>soil with only chemical fertilizer. In the case of soil water being constant, rising of temperature could result in increase in soil water unsaturated flow rate, the value of dk/dt was lower in soil with high rate corn straw than in soil with lower rate corn straw and soil with chemical fertilizer. With increase in relative partial molal free energy Δ(ΔG)] and relative partial molal enthalpy Δ(ΔH)], soil water unsaturated flow rate also increased, which was at the order of soil with high rate corn straw > soil with low rate corn straw>soil with only chemical fertilizer. The equations of Δ(ΔG)]and Δ(ΔH)] and k were founded.