Based on natural
evaporation experimentation of artificial control precipitation, two kinds of new type materials for preserving
soil moisture, high molecular water absorbent (HMWA) and water permeable plastic film (WPPF) are studied. The result shows that both materials have highly seasonal complementarity for preserving soil water in semiarid area with the characteristic of
continuous drought and intermittent wetting and drying.HMWA regulates soil moisture and
evaporation by improving soil physical property and porosity. Alhough the unit dry weight of mixed soil is slightly increased, its maximum field capacity and total porosity is not decreased but highly increased. Besides, the field capacity, non capillary porosity and aeration porosity is also increased along with the increase of amount of HMWA.The evaporation inhibiton of the mixed soil is higher in the period of intermittent wetting and drying than that of continuous drought. However, the evaporation inhibition of the WPPF mulch is higher in the period of continuous drought. The higher cover rate of the WPPF, the lower evaporation rate. WPPF mulch not only decreases upward movement of water in both covered and adjacent bare soil mass, but also increase horizontal movement of water from the covered soil mass to the bare soil mass, which apparently enhance soil moisture by 19.62% ~20.02% in adjacent bare soil mass and 43.17%~49.04% in covered soil mass compared with check test after a month time continuous drought.