Climate change in dry lands of Central Asia: from assessment methods to adaptation strategies

Global climate change is one of the main issues discussed at various international and intergovernmental meetings and consultations. Since the mid-1990s, the issue went beyond the scientific papers and discussions and became the subject of discussions among policy makers. Key issues of climate change impact on the environment, economic development, wellbeing, health and safety of the population, often discussed in various scientific and political forums, and many of them have been set up as priority for coordinated actions. In 1990, the First Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) has been published, which presented the first systematic scientific views on climate forecasts, assessment of the impact of global warming and measures to adapt to the upcoming changes. The Fourth Assessment Report of the WMO/UNEP Intergovernmental Panel on Climate Change (lPCC) released in 2007, suggested several adaptation strategies to deal with projected climatic changes which include, changing crop varieties; enhancing more efficient water use; appropriate scheduling of cropping activities; adoption of more effective pest, disease and weed management practices and insurance; and making better use of seasonal climate forecasts to reduce production risks. A comprehensive and integrated approach to planning and implementing the climate change adaptation strategies across the wide range of agroecosystems in different countries in CAC could help both the planners and the local communities to deal effectively with the projected impacts and also contribute to mitigation of climate change

Polycondensation type anion-exchange polymers

The influence of the reaction temperature, the ratio of the starting materials, the amount and nature of the solvent and other factors on the polycondensation of melamine with furfural in this present work was investigated. The rate of polycondensation reaction of melamine with furfural was studied at 100, 110, 120, 130 °С, the molar ratio of melamine to furfural was constant 1.5:1.0. It was noticed that at a temperature of 100°C the duration of the polycondensation reaction is 17 hours, the exchange capacity of the ion exchanger is 4,0 mEq/g, with an increase in temperature to 120 °C the exchange capacity reaches 4,8-5,0 mEq/g. On the basis of experimental data, the optimal temperature for the reaction of melamine polycondensation with furfural was 120 °С, at which the reaction course was uniform and an anion-exchange polymer formed in 7,5 hours, characterized by good physical, chemical and mechanical properties

Modifying Hargreaves-Samani equation for estimating reference evapotranspiration in dryland regions of Amudarya River Basin

Reference evapotranspiration (ETo) is a key factor in determining the amount of water needed for crops, which is crucial to correct irrigation planning. FAO Penman-Monteith (EToPM) is among the most popular method to estimate ETo. Apparently sometimes it is difficult to compute ETo using Penman-Monteith due to challenges on data availability. FAO Penman-Monteith method requires many parameters (solar radiation, air temperature, wind speed and humidity), while Hargreaves-Samani method calculates ETo based on air temperature. Because Central Asia is a data limited region with weather stations unable to provide all required parameters for the PM method, this study aimed to estimate ETo using the Hargreaves and Samani (HS) method in Karshi Steppe, in Kashkadarya province, in southern Uzbekistan, based on data from 2011 to 2017. Reference evapotranspiration calculated by non-modified HS method is underestimated during the summer months. The reason for this underestimation might be higher air temperature and wind speed during these months. Therefore, the HS method in its original form cannot be used in our study area to estimate ETo. Modification of the EToHS, through application of a bias correction factor, had better performance and allowed improving the accuracy of the ETo calculation for this region. The calculated ETo values can inform decision making and management practices regarding water allocation, irrigation scheduling and crop selection in dry land regions of Amudarya river basin and the greater Central Asia area

Growing cotton in Karshi Steppe, Uzbekistan: water productivity differences with three different methods of irrigation

In Uzbekistan, generally practiced methods of irrigating crops are varieties of flooding (basin, border and furrow). These practices have created problems of waterlogging, salinity and lower irrigation efficiency. Waterlogging and salinization already affect 50 percent of irrigated areas, and irrigation efficiency hardly reaches up to 50-60%. The Karshi Steppe of Kashkadarya region is among the prime cotton and wheat producing areas in Uzbekistan, using around 4.5 – 5.0 billion m3 of irrigation water within a hydrological year. About 75% of this water is abstracted from Amu Darya River in the territory of Turkmenistan and raised up to 135 meters, using a cascade of seven pumping stations to Karshi main canal. Research on implications of applying other irrigation technologies with different irrigation regimes on cotton crop are limited in Uzbekistan, especially under water scarce situations, such as in Karshi Steppe. This study targeted that knowledge gap and compared performance of cotton crop under different irrigation regimes with three technologies (furrows, gated pipes, and drip). The yield data ranged from 3.5 to 4.6 t ha-1, whereas water productivity (WP) values ranged from 0.44 to 1.20 kg m-3 and irrigation water use efficiency (IWUE) ranged from 0.51 to 1.41 kg m-3. The measured ranges of IWUE and WP are much wider compared with data available for Karshi Steppe. Due to cotton being sensitive to soil-moisture stress, lack of skillful technicians at site for irrigation scheduling has led to more water stress than was planned for, resulting in lower crop yields than expected

Water productivity of potato under improved irrigation techniques in Uzbekistan

Potato is a very important cash crop in Uzbekistan as the government has implemented several measures to increase its production to meet food security as well as to improve its export potential. However, irrigation water demand of potato is much higher than for other crops such as sorghum and maize, which normally consume less water and generate more income. Furrow irrigation is the main irrigation method used to grow potato in Uzbekistan. Introduction of improved irrigation methods could reduce the water used for potato production and provide alternative solutions to improving potato production and income security under water scarce conditions. There are few comparative studies on conventional furrow versus improved irrigation methods for potato production. This paper explores water productivity of two varieties of potato under four irrigation treatments in Andijan and Ferghana regions of Uzbekistan. At each location, four different irrigation treatments were evaluated. These four treatments were: conventional furrow irrigation (CFI), high frequency furrow irrigation (HFI), partial root zone drying irrigation (PRD), and drip irrigation (DrI). The experimental sites in each study area were established in 2012 on farmer fields. Data on water used and agronomic performance were collected from both study sites to calculate water productivity for each treatment. Analysis of Variance (ANOVA) was used to identify differences in treatments. The results indicate that, overall, high frequency furrow irrigation and drip irrigation treatments performed better than conventional furrow irrigation and partial root drying treatments. Research findings from this paper are useful for relevant stakeholders in Uzbekistan whose population is highly dependent on irrigated agriculture. Existing water use policies in Uzbekistan do not provide water users incentives for water saving as water delivery for agriculture is highly subsidized by the government resulting in excessive water use. These findings may help reduce unsustainable water use by increasing knowledge of relevant stakeholders including decision makers in order to improve water policies in the region

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

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 largescale 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

Heat units-based potential yield assessment for cotton production in Uzbekistan

Cotton yields in Uzbekistan are significantly lower than those in similar agro-climatic regions, requiring the estimation of crop potential and baseline yield to track progress of production enhancement efforts. The current study estimated potential cotton development and baseline yield (maximum given no production constraints) using total heat units (THU) and potential cotton yield (PCY), respectively. Calculations were based on heat units (HU) for a 30-year (1984-2013) period. Long-term average THU and PCY, as well as PCY at three different exceedance probabilities (p=0.99, p=0.80, and p=0.75), were calculated for 21 selected weather stations across cotton-growing areas of Uzbekistan. After confirmation that the current planting date (April 15) is optimal, a comparison of THU with the accepted cotton production cutoff threshold (1444°C) suggested that areas with lower elevations and latitudes are more appropriate for cotton production. Yield gap analysis (relative difference between long-term average PCY and actual yields) confirmed that Uzbekistan cotton production is below potential, while the spatial distribution of yield gaps outlined where efforts should be targeted. Areas near the stations of Nukus, Kungrad, Chimbay, and Syrdarya should be further investigated as benefit/cost ratio is highest in these areas. A comparison between state-set yield targets and PCY values, taking into account climatic variability, suggested that all areas except Jaslyk, Nurata, and Samarkand have safe, appropriate targets. These results present a starting-point to aid in strategic actions for Uzbekistan cotton production improvement