土壤磷扩散规律及其能量特征的研究　Ⅳ.土壤磷扩散的预测

DIFFUSION OF PHOSPHATE IN SOILS Ⅳ.PREDICTION

根据扩散系数受温度影响即温度影响水粘度的特性，提出不同温度下磷扩散预测的修正Nye模型为D＝D0κfθ／b（式中к粘度校正系数，其值等于25℃与预测温度水粘度之比）。并采用低的水／土比及低浓度范围吸附等温线的斜率（b），用该模型可以相当准确地预测土壤中磷的扩散系数，常温下尤其如此;在土壤水低吸力范围内，预测值与实测值相差一般不超过2倍。

On the basis of temperature influences on diffusion transmission factor (f) through influencing water viscosity (η), it was advanced that viscosity correction coefficient (κ) could be described by the equation κ=η(25)/ηx where η(25) and ηx stand for the water viscosity at 25℃ and x℃, respectively, and the modified Nye model to estimate the diffusion coefficient of phosphate in soil under varying temperatUre was in the form of D=D0 f θk/b. By using the adsorption isotherm slope (b) under a lower ratio of solution to soil and lower concentration of phosphate solution,the diffusion coefficient predicted by the model was in agreement with the diffusion coefficient measured, especially at indoor temperatUre. The ratio of the predicted phosphate diffusion coefficient to the measured phosphate diffusion coefficient in soil under low water tension condition(<105Pa) was lower than 2 in most cases.