Soil salinity dynamics in arid oases during irrigated and non-irrigated seasons

Preventing soil salinization is key to the healthy development of agroecosystems in arid regions. Notably, long-term anthropogenic irrigation accelerates secondary salinity accumulation in arid areas; however, the regional-scale spatial patterns of soil salinity pre- and post-irrigation season remain unclear. Accordingly, field observations over two periods (n = 182 samples), along with environmental covariates and the randomForest algorithm, were used to estimate the horizontal and vertical spatial distributions (12 soil depths) of soil salinity in the Weiku Oasis (0-60 cm) at a 30 m spatial resolution. The results showed that the prediction accuracy was greater for the non-irrigated season than for the irrigated season. Moreover, soil salinity was low in the interior of the oasis, high in the desert oasis interlacing zone, and significantly decreased with increasing soil depth. Variable contributions indicated that the effects of SoilGrids variables on soil salinity increased with greater soil depth. During the irrigation season, an inflection point for salt aggregation was observed at similar to 55 cm for farmlands, grasslands, and shrubs, with the greatest variation seen in farmlands. The findings here provide insights into the improvement of irrigation techniques in arid zone agroecosystems.