Soil water and root distribution under jujube plantations in the semiarid Loess Plateau region, China

This study aimed to analyze the spatial correlation between soil water and root distribution in dense-dwarf jujube plantations in the Hilly Loess Region (HLR) of China. The soil coring method was used to sample roots at different depths within the 0–1,000 cm soil profile. The results showed that increase in average annual root depth decreased with increasing jujube stand age. The maximum root depth of the 12-year-old jujube was 520 cm. The difference between the maximum and minimum root depths in the 12-year-old jujube trees was 180 cm. Lateral roots started developing intersection networks 3 years after planting. Soil water fluctuation was not induced by vertical root systems of dense-dwarf jujube plants. With increasing jujube stand age, root depth, dry soil layer depth (below 240 cm) and annual soil water variance within the top 0–200 cm soil layer increased. However, root-zone soil water content decreased with increasing stand age while dry soil layer depth was slightly larger than root depth. The results of this study have important significance to provide vital technical support for jujube cultivation especially under semiarid conditions and were expected to find application in water management for plantations in the HLR.