Soil salinization and sodification are common processes that particularly characterize drylands. These processes can be attributed either to natural conditions or anthropogenic activities. While natural causes include factors such as climate, lithology, topography, and pedology, human causes are mostly related to agricultural land-use, and specifically, to irrigated agriculture. The objective of this study was to thoroughly review this topic, while highlighting the major challenges and related opportunities. Over time, the extent of saline, sodic, and saline-sodic croplands has increased, resulting in accelerated land degradation and desertification, decreased agricultural productivity, and consequently jeopardizing environmental and food security. Mapping and monitoring saline soils is an important management tool, aimed at determining the extent and severity of salinization processes. Recent developments in advanced remote sensing methods have improved the efficacy of mapping and monitoring saline soils. Knowledge on prevention, mitigation, and recovery of soil salinity and sodicity has substantially grown over time. This knowledge includes advanced measures for salt flushing and leaching, water-saving irrigation technologies, precision fertilizer systems, chemical restoration, organic and microbial remediation, and phytoremediation of affected lands. Of a particular interest is the development of forestry-related means, with afforestation, reforestation, agroforestry, and silvopasture practices for the recovery of salt-affected soils. The forecasted expansion of drylands and aggravated drying of existing drylands due to climatic change emphasize the importance of this topic.

Tugai forests are the riparian forests along the rivers in the continental desert regions of Central Asia, i.e. the Tarim River, Amu Darya and Syr Darya. They mainly consist of Populus euphratica Oliv., Populus pruinosa Schrenk. and Elaeagnus oxycarpa Schltdl. As a consequence of land opening campaigns, large areas of Tugai forests were destroyed after the 1950s. Due to excessive use of water for irrigation, the remaining Tugai forests are under severe threat. Near natural Tugai forests still exist along the Tarim middle reaches in the Tarim Huyanglin Nature Reserve, Xinjiang, NW China. There is a gap in understanding, how the seedlings of P. euphratica establish as trees which continuously connect to the groundwater. Therefore, the set of conditions which must be met for germination and successful establishment, i.e. formation of Tugai forests, was investigated along a representative transect still under natural conditions. P. euphratica seedlings germinate in belts during the retreat of the summer flood on freshly deposited sites bare of other vegetation. Such germination sites are formed by river dynamics. While germination takes place regularly in the study area, successful establishment is restricted to few germination events. Seedlings face dropping groundwater levels during spring and early summer of the second year after germination. Therefore, for successful establishment, it is essential that the flood of the second year starts in time and is high enough, in order to replenish the groundwater. Furthermore, clayey soil layers in the subsoil may play a role for successful establishment, too, as they store water better than sandy soil layers.

The Ili River is a transboundary river shared by China, upstream, and Kazakhstan, downstream. The Ili is the main water supplier to Lake Balkhash, the largest lake in Central Asia after desiccation of the Aral Sea. Agreements over water allocation have not been concluded between China and Kazakhstan. This paper investigated water consumption of agriculture and riparian ecosystems in the Ili river basin, to provide information for further debate on water allocation, through the Simplified Surface Energy Balance Index (S-SEBI) approach using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images. The overall water consumption in the Ili river basin was 14.3 km3/a in 2000, 17.2 km3/a in 2005, and 15 km3/a in 2014. In 2000, China and Kazakhstan consumed 38% and 62% of the water, respectively. By 2014, the relative share of China’s water consumption increased to 43%. In China, 80% of the water consumption is due to agriculture. High runoff during the past 10 years enabled increasing water consumption in China and sufficient water supply to agriculture and riparian ecosystems in Kazakhstan. When runoff of the Ili River decreases, as expected for most rivers in Central Asia, then irrigation efficiency has to be further increased in China, and irrigation systems in Kazakhstan have to be restored and modernized in order to reduce water consumption and protect Lake Balkhash and the riparian ecosystems.