Akmal Karimov

Development of magnesium-dominant soils under irrigated agriculture in southern Kazakhstan.

ABSTRACT Irrational irrigation practices in the Arys Turkestan Canal command area in the southern part of Kazakhstan have led to the formation of soils with poor physical and chemical properties. To study whether irrigation and leaching practices and/or groundwater rise have contributed to the accumulation of Mg 2+ on the cation exchange complex of these soils, historical changes in soil and groundwater quality were used as source data and the Visual MINTEQ model was applied to analyze the chemical composition of water and soils in the study area. The imposed irrigation regime and the leaching of light sierosem soils led to the dissolution and subsequent leaching of inherent gypsum and organic matter from the soil profile. Further, the domination of bicarbonate in the irrigation water promoted weathering of the carbonate minerals present as calcite. The higher concentrations of Mg 2+ in comparison to Ca 2+ in the irrigation water resulted in the replacement of Na + by Mg 2+ on the cation exchange complex. In the lower part of the command area, shallow groundwater has contributed to the accumulation of Na + and to a large extent of Mg 2+ on the cation exchange sites.

Modelling policy alternatives toward managed aquifer recharge in the Fergana Valley, Central Asia

Storing flow of the Syrdarya River in the aquifers of the upstream Fergana Valley in winter and recovery of this water in summer is examined as a solution for competing demands between upstream hydropower and downstream irrigation. Modelling of the Isfara and Sokh aquifers suggests the potential of reducing the Syrdarya River flow to the Fergana Valley downstream by 540 Mm3 in winter and increasing it by 540 Mm3 in summer. Implementing the proposed strategy in only these two aquifers would cover over 25% of the summer water deficit in the Syrdarya River downstream.

Land and Water Resources of Central Asia, Their Utilisation and Ecological Status

Central Asia is the global hotspot of a nexus of resources. Land, water and food are key issues in this nexus. We analysed the status of land and water resources and their potential and limitations for agriculture in the five Central Asian Transition States. Agricultural productivity and its impacts on land and water quality were also studied. The ecological status of open waters and soils as dependent on the kind of water and land use was shown. The main sources were information and data from the scientific literature, recent research reports, the statistical databases of the FAO and UNECE, and the results of our own field work. Agriculture is crucial for the economy of all Central Asian countries and responsible for about 90 % of their water use. We found that land and water resources may provide their function of food supply, but the agricultural productivity of grassland and cropland is relatively low. Irrigation agriculture is sometimes inefficient and may cause serious detrimental side effects involving soil and water salinisation. Dryland farming, as currently practiced, includes a high risk of wind and water erosion. Water bodies and aquatic, arable and grassland ecosystems are in a critical state with tendencies to accelerated degradation and landscape desertification. Despite all these limitations, agricultural landscapes in Central Asia have great potential for multi-functional use as a source of income for the rural population, tourism and eco-tourism included. The precondition for this is a peaceful environment in which they can be developed. All major rivers and their reservoirs cross borders and involve potential conflict between upstream and downstream riparians. The nexus of resources requires more detailed research, both in the extent of individual elements and processes, and their interactions and cycles. Processes in nature and societies are autocorrelated and intercorrelated, but external disturbances or inputs may also trigger future developments. We emphasise the role of knowledge and technology transfer in recognising and controlling processes. There has been a lot of progress in science and technology over the past ten years, but agri-environmental research and education in Central Asia are still in a crisis. Overcoming this crisis and applying advanced methods in science and technology are key issues for further development. Science and technology may provide an overall knowledge shift when it comes to recognising processes and initiating sustainable development. The following chapters introduce the results of further, more detailed and regional analyses of the status of soil and water. Novel measurement and assessment tools for researching into, monitoring and managing land and water resources will be presented. We will inform future elites, scientists and decision makers on how to deal with them and encourage them to take action.

Enhancing the Productivity of High-Magnesium Soil and Water Resources in Central Asia

High-magnesium soils and waters are emerging environmental and agricultural productivity constraints. Excess levels of magnesium (Mg2+) in irrigation waters and/or in soils negatively affect soil infiltration rate and hydraulic conductivity and ultimately crop growth and yield. Although the levels of Mg2+ in irrigation waters and soils are increasing in several irrigation schemes globally, southern Kazakhstan has become a hotspot of such natural resource degradation. The productivity of magnesium-affected soils can be enhanced by increasing the levels of calcium (Ca2+) in the soil to counteract the negative impacts of Mg2+. Studies undertaken on the soil application of phosphogypsum, a major waste product of phosphoric acid factories and a source of Ca2+, have demonstrated beneficial effects of this soil amendment in terms of (1) improved soil quality through a reduction in exchangeable magnesium percentage (EMP) levels; (2) enhanced water movement into and through the soil vis-a-vis increased moisture storage in the soil for use by the plant roots; (3) increased cotton yield and water productivity; and (4) greater financial benefits. In addition to improving crop productivity, these studies demonstrated the beneficial use of an industrial waste material in agriculture. With the aim of addressing the challenge of achieving sustainable agriculture production from magnesium-affected environments, there would be a need for appropriate supportive policies and functional institutions along with capacity building of farmers, researchers, and agricultural extension workers.

Can a change in cropping patterns produce water savings and social gains: A case study from the Fergana Valley, Central Asia

Abstract The study examines possible water savings by replacing alfalfa with winter wheat in the Fergana Valley, located upstream of the Syrdarya River in Central Asia. Agricultural reforms since the 1990s have promoted this change in cropping patterns in the Central Asian states to enhance food security and social benefits. The water use of alfalfa, winter wheat/fallow, and winter wheat/green gram (double cropping) systems is compared for high-deficit, low-deficit, and full irrigation scenarios using hydrological modeling with the HYDRUS-1D software package. Modeling results indicate that replacing alfalfa with winter wheat in the Fergana Valley released significant water resources, mainly by reducing productive crop transpiration when abandoning alfalfa in favor of alternative cropping systems. However, the winter wheat/fallow cropping system caused high evaporation losses from fallow land after harvesting of winter wheat. Double cropping (i.e., the cultivation of green gram as a short duration summer crop after winter wheat harvesting) reduced evaporation losses, enhanced crop output and hence food security, while generating water savings that make more water available for other productive uses. Beyond water savings, this paper also discusses the economic and social gains that double cropping produces for the public within a broader developmental context.