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Farmers face increased risks and vulnerability to the effects of climate change and land degradation on crop production due to the lack of information and impact assessment. This is especially true in the Khorezm, an irrigated agricultural region near the Aral Sea Basin (Uzbekistan) which represents eight million of irrigated land in Central Asia. Water scarcity requires research and introduction of alternative crops into a common winter wheat–cotton rotation. Mung bean (Vigna radiata) is considered as a drought-tolerant crop that could be implemented in Khorezm and other similar drought prone areas. The main objective of this study was modeling the triple rotation sequenced the winter wheat (WW), summer mung bean (MB) and cotton (C) as a single cropping system. Specific objectives were to (1) update the parameterization of the irrigated winter wheat and cotton modules in CropSyst to identify the key variables impacting the triple rotation (WW–MB–C) on overall crop yield; (2) to parameterize and validate the developed (CropSyst-based) model using controlled triple rotation data and (3) carry out scenario analyses to capture the influence of soil fertility levels and irrigation water shortage on crops growth, development and yields. The results revealed, for the first time, the impact of different soil-ecological factors such as high soil fertility (HSF) and low soil fertility (LSF) varying levels of irrigation water availability on crops in the triple crop rotation. Compared to LSF simulated yields of winter wheat and cotton under HSF were increased with 0.58 Mg ha−1for WW grain and 0.21 Mg ha−1for cotton while mung bean grain yields were not affected by different soil fertility levels. Scenario analyses showed the possibility of reduced (by 20%) irrigation for triple crop without the effect on yield. However, compared to full irrigation scenario, reduction of irrigation for 40 and 60% could decrease the rotation crops yields up to 33% and 40%, respectively. The developed model could be useful to increase the understanding of the nexus of food, energy and water in Khorezm and comparable regions of Central Asia, and to inform decision-making about sustainable use of available water resources.

Abstract: Winter wheat is the most important cereal in Uzbekistan. Although the processing industry recognizes the low quality of local wheat, the present land use policy prioritizes production quantity, and wheat of better quality is imported to improve local flour. Yet, with increasing world market prices, Uzbekistan has to decide whether to continue allocating considerable resources for imports or to start investing in local quality improvements. This study therefore analyzed wheat production in the Khorezm region of Uzbekistan by (a) assessing the economic feasibility of local production vs. imports; and by (b) evaluating the current N-fertilizer management at field level in order to identify options for improving quality. Demand for wheat in the region currently falls short of supply by 79,000 t but under favorable world market prices, funds for importing additional wheat could be covered by cotton sales. Prices above $148 USD t−1 support the present land use policy to cultivate wheat but the baking quality of the crop is low. Higher N rates and/or an additional application of N at anthesis significantly increased grain quality. Additional costs for changes in N management, however, are currently not compensated by the price premiums at the State mills. Thus, in the absence of price incentives, it is unrealistic to expect producers to maximize quality production. Consequently, administrators must give quality greater attention by creating incentives through price differentials for higher quality, and encouraging awareness programs on wheat quality and improved on-field N management.