干旱区生态环境知识资源中心

A line source sprinkler was used to determine water requirements of adapted species for revegetation of abandoned farmlands in the Sonoran Desert of southern Arizona. Six grass and seven woody species were seeded on a fine-sandy soil initially at field capacity water content during the summers of 1992 and 1993 in Tucson, Arizona. The line source sprinkler created a greater difference in soil water availability between irrigated and unirrigated soils than within the irrigation gradient itself. Initial irrigation was followed by periods of summer rainfall in both years. Species emergence and establishment varied with amount and timing of irrigation and summer rainfall. After the initial 14 days of irrigation in 1992 and 11 days in 1993, soil water availability was intermittent in the surface soil but was consistently high at depths greater than 18 cm. Emergence was more sensitive to the irrigation gradient than was plant survival. Most species established successfully with at least 210 mm of irrigation plus precipitation. A possible strategy for establishing many of these species on abandoned farmland would be to fill the soil profile to field capacity by irrigating on consecutive days until emergence is observed. Direct seeding without irrigation or water concentration is not recommended due to the erratic and limited nature of summer rainfall on abandoned farmland in the lower Sonoran Desert.