含盐量对土壤的水汽吸附及土壤水能量状态的影响

The Effect of Salt content on Vapor Adsorption and Water Potential in Salt-affected Soils

以甘肃景电灌区盐化土壤为对象用水汽平衡吸附法就盐分对土壤的水汽吸附和土壤水能量状态的影响进行了研究 .结果表明盐分显著增加了土壤水汽吸附量 ,水汽饱和度为 98%的情况下 ,含盐量为 1 0 .772 g/kg和 1 2 .887g/kg的两个土壤的水汽吸附量分别达到了 1 9.4 5 %和 2 5 .34 % .水汽饱和度大于65 %左右时水汽吸附有一个明显的转折点 ,.水汽饱和度大于 65 %时水汽吸附量主要受含盐量影响 ,而当饱和度小于 65 %时则主要受物理性粘粒含量的影响 .盐分非常显著地降低了土壤的水势 ,可以用盐化土样的水势与脱盐处理土样的水势估算盐化土样的渗透势 .

The effect of salt contents on water vapor adsorption and water potential in salt-affected soils were assessed by a vapor pressure equilibrium method. The obtained results showed that salt contents significantly increased vapor adsorption. There was a threshold at about relative vapor pressure of 65%. Above the point, the vapor adsorption amount was more related to relative pressure, whereas below that point it was more related to the particle smaller than 0.01mm. Salt contents significantly decreased soil water potential. Osmotic potential could be estimated by the difference between the potential of natural salt-affected soil and that of the salt-leached soil. The estimated results showed that the absolute value of osmotic potential of salt-affected soils were far larger than that of matrix potential within a fairly large range of gravimetrical moisture contents.