Abstract: This paper studied the soil evaporation in potato field in semi-arid area under effects of covering ridge with plastic film (CR), uncovering ridge but compacted (UR), and belt planting on flat soil without ridge (CK). The results showed that in the whole growth season of potato, soil evaporation was 122.9-165 mm, 90.9-101.2 mm, and 80.7 mm under CR, UR, and CK, respectively. Treatment CR₆₀ had the maximum soil evaporation (2.6 mm·d^-1) at maturing stage, with a mean of 1。46 mm·d^-1, while the soil evaporation in CK was 0。65 mm·d^-1. In treatment UR₃₀, soil evaporation was the minimum (0。2 mm·d^-1) at seedling stage, with a mean of 0。39 mm·d^-1, while CK was 0。58 mm·d^-1. However, water surface evaporation was the maximum at budding and flowering stages, with the daily average evaporation being 8.3 mm and 9.0 mm, respectively, and not in-phase with soil evaporation. At maturing stage, soil evaporation was the maximum in all treatments. It was suggested that covered ridge had high efficiency of rainfall harvesting, but owing to its maximum soil evaporation, measures should be taken to inhibit soil evaporation to increase water use efficiency.

Key words: forest fire, secondary disaster, debris flow.