Abstract:

Based on the fixed field monitoring data of soil water content during the growing season in three different plantations(Populus hopeiensis, Populus sinmnii, and Caragana korshinskii), by means of soil water characteristic curves the authors studied the soil water holding ability, the specific water capacity as well as soil available water of three plantations at different period of growing seamn in different precipitation year. The results were as follows:Of the P. Hopeiensis, P. Sinmnii, and C. Korshinskii plantations the soil water holding capacity was relatively lower. Among them the soil water holding capacity and the specific water capacity had the following order:P. Hopeiensis plantation. > P. Simonii plantation > C. Korshinskii plantation. Although the dynamics of SAW(soil available water)in a certain year was deternfined mainly by the amount and seasonal distribution of rainfall it was also influenced by the successive years of drought. Therefore when the precipitation during the growing season was 494.3mm(1992), 234.8mm(1993), 338.5mm(1994)and 651.6mm (1995), respectively, the SAW content had following order:1995 > 1992 > 1993 > 1994. There was little of SAW content during the early period of the growing season in 1992 and 1995, and it was even quite low during the whole growing season in 1993 and 1994.

Key words: Soil water characteristic curve, Soil water holding capacity, Soil available water, Plantation, Loess region