东北黑土区土壤凋萎湿度研究

A Study of Permanent Wilting Point in the Northeast Black Soil Regions

以第二次全国土壤普查资料为基础，调查了东北黑土区黑土类中23个土种的典型剖面，测定了土壤凋萎湿度及相关理化性质，在分析黑土土种凋萎湿度特征及其与土壤理化性质关系的基础上，建立了分别利用土壤理化性质和最大吸湿水计算土壤凋萎湿度的两种方法。研究区23个土种的土壤凋萎湿度变化为9．45％～22．67％，平均为14．90％。随厚度略有增加．但变化不大。3个黑土亚类中，黑土的凋萎湿度最大，白浆化黑土最小。土壤凋萎湿度与机械组成，土壤容重和有机质含量有显著的相关性，可分别利用粘粒含量一个指标，粘粒含量与砂粒含量两个指标。粘粒含量、砂粒含量和容重3个指标计算估算土壤凋萎湿度，且选取变量越多估算效果越好。也可利用土壤最大吸湿水估算土壤凋萎湿度：PWP=1．4742×MH＋0．6292。对这些估算方法的检验结果表明，利用土壤理化性质和利用最大吸湿水估算的土壤凋萎湿度与实测结果没有差异，建议方法是可行的。

The soil permanent wilting point （PWP） is one of the most important hydrological parameters, but it can＇t be found in present general detailed soil survey material. The article, based on the second national soil survey of China, typical profiles of 23 black soil local type had been investigated again in the Northeast black soil regions. PWP and most of important soil physico-chemistry properties had been determined. The charac- teristic of PWP of the soil local type, the relationship between PWP and some soil physico-chemistry properties were analyzed. Two computational methods of PWP using physico-chemicaI properties and soil maximum hygroscopicity were established. The PWP change between 9. 45%-22. 67% in the research area, the mean value is 14. 90%. Though there were an increase tendency to the changes of PWP with soil profile depth, the fluctuation was not obvious. The black soil got biggest PWP in three black soil subgroups,Albic black soils was the lowest one. The PWP is significantly correlated to soil mechanical component, soil density and organic matter content, it can be calculated by clay content or clay content and sand content or clay content, sand content and soil density. The more variables are chosen, the better the estimated results are. Another equation to calculate PWP with soil maximum hygroscopicity were got, the formula is. PWP = 1. 4742× MH ＋0. 6292. The validity of the two methods to calculate PWP had been testified, result indicated that there were no significant difference between measured PWP and calculated PWP, so the suggested methods are feasible.