|Evett, Steven - Steve|
Submitted to: International Irrigation Show
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2003
Publication Date: 11/1/2003
Citation: IBRAGIMOV, N., EVETT, S.R., ESANBEKOV, Y., KAMILOV, B., HENG, L. 2003. COTTON AND WINTER WHEAT IRRIGATION SCHEDULING IMPROVEMENTS IN UZBEKISTAN. PROCEEDINGS OF THE INTERNATIONAL IRRIGATION ASSOCIATION TECHNICAL CONFERENCE "UNDERSTANDING AND ADDRESSING CONSERVATION AND RECYCLED WATER IRRIGATION." INTERNATIONAL IRRIGATION SHOW. P. 26-34. 2003 CDROM. Interpretive Summary: Since Independence in the early 1990s, Uzbekistan has rapidly increased winter wheat irrigated area in what earlier was nearly a cotton monoculture. Almost all agricultural production in the country, and in the surrounding Central Asian region, is dependent upon irrigation. Because of the importance of irrigated cotton and winter wheat production and because of its continental climate (semi-arid to arid), Uzbekistan has similar problems to those of the Southern High Plains of Kansas, Oklahoma, and Texas, including limited and declining water supplies. We used techniques for calibrating the neutron moisture meter, developed at Bushland, Texas, to calibrate these meters in Uzbekistan for use in determining crop water consumption and efficient irrigation scheduling regimes there. This proved the relevance of techniques developed at Bushland in other soils and surroundings. We also studied drip irrigation compared with furrow irrigation for cotton, and found that drip irrigation led to 21% larger yields while saving 35% of irrigation water, similar to findings in the Southern High Plains. Finally, we determined irrigation scheduling guidelines based on moisture meter measurements that allowed more water-efficient production of both cotton and winter wheat. The similar findings in Uzbekistan and Texas bolster the idea that both irrigation methods and scheduling are key components of more efficient use of water in agriculture.
Technical Abstract: Investigations of water use (evapotranspiration or ET) and irrigation scheduling of furrow irrigated winter wheat (Triticum aestivum L.) and of drip irrigated cotton (Gossypium hirsutum, cv. Akdarya-6) were conducted at the Central Experiment Station of the Uzbekistan Cotton Growing Research Institute (UNCGRI) on a deep silt loam soil in 2000, 2001, and 2002. Water use was established using the soil water balance approach on a weekly basis. Deep measurements of the soil profile water content were accomplished using soil moisture neutron probes (SMNP), which were calibrated in polyvinyl chloride (PVC) access tubes for the soil and each soil horizon. Water use was measured by the soil water balance method. Soil water measurements were compared with percentages of field capacity to determine irrigation rates and times during the growing season. The results revealed that drip irrigation of cotton under the given circumstances improved water use efficiency and seed-cotton yield. Under drip irrigation, the optimal mode of cotton irrigation scheduling was to irrigate at 70%, 70%, and 60% of field capacity during each of the three major growth stages, respectively. This mode saved 35% of the irrigation water in comparison with surface irrigated cotton grown under the same condition. Seed-cotton yield was increased by 21% relative to the surface irrigated cotton. Optimal development and high crop productivity of winter wheat was reached when irrigations were scheduled at soil moisture levels of 75, 75, and 60% of field capacity during the three major crop growth stages, respectively. More irrigation did not result in additional yield from the crop.