Dried soil layer is a universal and special soil hydrological phenomenon on Loess Plateau.Studying the state

reason and controlling measures of dried soil layer has much significance to regional plant capability

land productivity and rectification of low-functional forest and grassland and construction of sustainable plant.A universal assessing indicator of dried soil layer and reasonable broken values is the basis of dried soil layer study.Yet till now there is not a general assessing indicator and reasonable broken values

as results in the difficulty of the study on regional dried soil layer.Saturation or non saturation of soil available water was suggested to be an assessing indicator in this paper

and some broken values was also given based on the summarization of the present results.Calculation of saturation of soil available water calculates is simple and the indicator can be a universal assessing method.