To reduce soil salinity: the role of irrigation and water management in global arid regions across development phases

Reducing soil salinization of croplands with optimized irrigation and water management is essential to achieve land degradation neutralization (LDN). The effectiveness and sustainability of various irrigation and water management measures to reduce basin-scale salinization remain uncertain. Here we use remote sensing to estimate soil salinity of arid croplands from 1984 to 2018. We then use Bayesian network analysis to compare the spatial-temporal response of salinity to water management, including various irrigation and drainage methods, in ten large arid river basins: Nile, Tigris-Euphrates, Indus, Tarim, Amu, Ili, Syr, Junggar, Colorado, and San Joaquin. Managers in basins at more advanced phases of development implemented drip and groundwater irrigation, which effectively controlled salinity by lowering groundwater levels. For the remaining basins where conventional flood irrigation is used, economic development and policies are crucial to establishing a virtuous circle of ‘improving irrigation systems, reducing salinity, and increasing agricultural incomes’ necessary to achieve LDN.