Moisture storage, transport and mixing processes after sprinkler irrigation of Pasture cropland: Understanding based on water isotopes

Abstract. The processes of water storage, migration, and mixing in agricultural fields are influenced by a combination of factors, including climatic conditions, soil properties, cropping structure, and field management practices. Sprinkler irrigation is a widely adopted method in agricultural fields globally. Studying the post-irrigation processes of sprinkler irrigation in specific regions can provide valuable insights for regional agricultural development and the conservation and utilization of water resources. In this study, we investigated the water storage, migration, and mixing processes in vegetation within arid irrigated areas. This was achieved by analyzing stable isotope data, using sprinkler-irrigated pastureland (alfalfa) as the research subject. The study results indicated that: (1) there was significant isotope depletion in soil moisture following irrigation, with soil moisture and isotope characteristics returning to their pre-irrigation state after an average of 9 days; (2) water transport in the soil was predominantly vertical, with a minimal proportion of horizontal movement; and (3) evaporation losses due to sprinkler irrigation accounted for 32 %, while losses from excess irrigation (infiltration into soil layers below 60 cm) comprised 5 %. In arid regions, sprinkler irrigation effectively controls infiltration losses; however, evaporation losses remain considerably high. We recommend promoting low-level multipoint sprinkler irrigation and nighttime irrigation practices to enhance water use efficiency and ensure agricultural sustainability.