In this paper

characteristics of soil aridity in the upland of the Longdong Loess Plateau was determined through the analyses of soil water content of different periods in different layers of wheat field on the typical/Dongzhi Upland0. Analyses indicate that from the top soil layer down to the lower

frequency of soil aridity occurrence gradually increases

but soil aridity degree gradually weakens. Severe soil aridity mostly occurs between the end of spring and the early days of summer

and has the highest probability of occurrence in the upper and middle parts of a soil profile. Usually

severe aridity does not take place below a depth of 1m. Excess wetness mostly occurs in autumn

and has the highest probability in the middle and low parts of a soil prof ile. Usually

ex cess wetness does not take place within 1m of the upper layer. Soil water content in wheat field reaches a maximum in late autumn. The most arid time is betw een the end of spring and early summer. Severe soil aridity takes place with a little probability in early spring.