Salt‐induced land and water degradation in the Aral Sea basin: A challenge to sustainable agriculture in Central Asia

Abstract

Expansion of irrigated agriculture in the Aral Sea Basin in the second half of the twentieth century led to the conversion of vast tracks of virgin land into productive agricultural systems resulting in significant increases in employment opportunities and income generation. The positive effects of the development of irrigated agriculture were replete with serious environmental implications. Excessive use of irrigation water coupled with inadequate drainage systems has caused large‐scale land degradation and water quality deterioration in downstream parts of the basin, which is fed by two main rivers, the Amu‐Darya and Syr‐Darya. Recent estimates suggest that more than 50% of irrigated soils are salt‐affected and/or waterlogged in Central Asia. Considering the availability of natural and human resources in the Aral Sea Basin as well as the recent research addressing soil and water management, there is cause for cautious optimism. Research‐based interventions that have shown significant promise in addressing this impasse include: (1) rehabilitation of abandoned salt‐affected lands through halophytic plant species; (2) introduction of 35‐day‐old early maturing rice varieties to withstand ambient soil and irrigation water salinity; (3) productivity enhancement of high‐magnesium soils and water resources through calcium‐based soil amendments; (4) use of certain tree species as biological pumps to lower elevated groundwater levels in waterlogged areas; (5) optimal use of fertilizers, particularly those supplying nitrogen, to mitigate the adverse effects of soil and irrigation water salinity; (6) mulching of furrows under saline conditions to reduce evaporation and salinity buildup in the root zone; and (7) establishment of multipurpose tree and shrub species for biomass and renewable energy production. Because of water withdrawals for agriculture from two main transboundary rivers in the Aral Sea Basin, there would be a need for policy level interventions conducive for enhancing interstate cooperation to transform salt‐affected soil and saline water resources from an environmental and productivity constraint into an economic asset.

Effects of the shallow water table on water use of winter wheat and ecosystem health: Implications for unlocking the potential of groundwater in the Fergana Valley (Central Asia)

“…The vast irrigation development and over irrigation practices have also led to extensive land degradation in the areas irrigated with waters from Amudarya and Syrdarya rivers. According to recent estimates, nearly 50% of the irrigated areas in Central Asia are salt affected, water logged, or both (Qadir et al, 2009). The deterioration and poor health of the rivers and ecosystems potentially threatens the livelihoods of tens of millions who depend on them for food security and incomes.…”

Cropping Intensity in the Aral Sea Basin and Its Dependency from the Runoff Formation 2000–2012

“…For the Khorezm region, again impact of the Tuyamuyun Reservoir is indicated, whereas high soil salinity, which affects nearby all cropland in Turkmenistan [51] and in particular that part of the Amu Darya Delta [79], may be a plausible explanation for the reduced use of cropland there and for the reduced CI in CZ 7. Also within the different irrigation systems (at the local scale), numerous factors such as water distribution problems, which occur at different scales and may range from infrastructure problems [1,2] to political, social, and institutional challenges [6,80,81], soil salinity and shallow groundwater [12,14], or other reasons can influence CI and PF. However, this cannot be clarified in this study.…”

“…For instance, information on the actual intensity of cropland use in the different irrigation systems and on the effects of upstream runoff generation on irrigated cropland use can enrich the analysis of land and water use options [2] including assessments of potential for saving remnants of the vastly destroyed natural ecosystems [11]. It can also strengthen the explanation of spatial patterns of widely-occurring land degradation [12] and in turn the identification of priority sites for alternative land use options [13,14].…”

Mapping Cropland Abandonment in the Aral Sea Basin with MODIS Time Series

“…This region experienced precipitous population growth in the mentioned countries, increasing from 61 million people in 1990 to 104 million by 2016; the rural population is strongly dependent on the domestic agricultural production [6]. Despite increasing food demand, official statistics and exemplary case studies with satellite imagery suggest that agricultural land abandonment is common in this region and most likely occurs on degraded, irrigated agricultural lands [7][8][9][10].…”