Effect of saline water irrigation on soil development and plant growth in the Taklimakan Desert Highway shelterbelt

Abstract

Water scarcity is a world-wide problem, especially in desert ecosystems. To overcome this shortage, saline groundwater is increasingly being used, although it has risks of increasing soil salinity and causing plant salt toxicity. In this study, we investigated the effects of saline water irrigation on soil properties and plant growth along the Taklimakan Desert Highway shelterbelt. The results showed that soil salts (about 8mScm−1) and nutrients significantly accumulated at the soil surface (crust and 0–10cm soil layers) with saline irrigation, but the soil salinization did not increase (<1.0mScm−1) within the 40–60cm soil depth where abundant lateral roots also germinated and extended horizontally. While the deepest main root system was 200cm for Tamarix, it extended to about 150cm for other two species studied (Haloxylon and Calligonum). More than 87% of the biomass of the lateral roots was present in the 20–80cm soil depths for the three species; although no active absorbing roots were found within the 0–10cm soil depths where the salts had accumulated. These findings indicated that saline water irrigation within artificial shelterbelts may be beneficial for soil nutrient accumulation and accentuates the potential uses of these sandy soils. After 7-yrs irrigation with nutrient accumulation, structured soil under shelterbelt has progressively formed, as indicated by increased soil aggregate size and stability. Saline water irrigation did not influence the normal growth of adaptive plants, which may be attributed to the plant adaptability to salt stress through root morphology adjustment. In summary, saline groundwater irrigation offers potential advantages and opportunities for plant growth on sandy soils evolution in a desert environment where saline groundwater is the sole water resource for plants.