Soil water consumption characteristics in rain-fed apple orchards and wheat fields

Abstract

Agricultural production in Weibei rain-fed highland, Northwest China, is facing severe drought and water shortages. Here, soil water consumption characteristics in rain-fed orchards and farmlands were explored to ascertain the rationality of planting orchards in Weibei. Soil moisture dynamics was monitored in the 0-150-cm soil profiles of different aged Red Fuji apple orchards (young: 7 years, mature: 13 years, and old: 22 years), and in long-term cultivated winter wheat fields during the growing season of apple trees. The over-consumption and consumption of soil water were analyzed to evaluate water stress and differential water consumption by distinct vegetation, respectively. Soil desiccation index was used to determine the occurrence of dry soil layers. Generally, there was no water stress in the 0-150-cm orchard soil profiles, while water stress was observed at the 0-70-cm soil depths in the old orchards (mid-June) and farmlands (mid-May-mid-July). Water consumption took place at deeper depths for longer periods in the older orchards than in the younger orchards. Soil desiccation was not observed in the young orchards, while mild desiccation occurred at the 0-80-cm soil depths in the mature and old orchards in mid-June. The desiccation intensity was mild at the 0-60-cm soil depths in mid-April-mid-May, intense at the soil 0-150-cm depths in mid-June, and moderate at the 20-150-cm soil depths in mid-July. In conclusion, conversion from wheat fields to apple orchards could reduce soil water stress, reduce dry soil layers, and mitigate soil desiccation in the rain-fed highland area.