Qureshi A.S.,International Water Management Institute IWMI |
Eshmuratov D.,International Water Management Institute IWMI |
Bezborodov G.,Uzbekistan Cotton Research Institute
Irrigation and Drainage | Year: 2011
Poor on-farm irrigation practices and rising groundwater table depths are the major reasons for low cotton yields in the Sardarya province of Uzbekistan. To ensure sustainability of cotton production in the area, precise calculations of irrigation requirements are needed to optimize crop yields and to keep groundwater table depth below the root zone to avoid soil salinization. To determine optimal groundwater table depth and irrigation amounts for the Sardarya province of Uzbekistan, the Soil-Water-Atmosphere-Plant (SWAP) model was used. SWAP was calibrated and validated using measured data from an experimental cotton field during the agricultural year of 2006 and 2007. The calibrated SWAP model was then used to simulate optimal groundwater table depth and irrigation amounts. The simulation results show that for the existing conditions in the study area, a groundwater table depth of approximately 200cm together with an irrigation application of 2500m3 ha-1 will be the most appropriate combination for optimal cotton yields (≈ 3.0 t ha-1). However, to achieve maximum potential yields of cotton (5-6 t ha-1), leaching of excessive salts from the root zone through freshwater application would be imperative. This would require rehabilitation of the existing drainage network in the area. © 2010 John Wiley & Sons, Ltd.
Ibragimov N.,Uzbekistan Cotton Research Institute |
Evett S.,U.S. Department of Agriculture |
Esenbekov Y.,Uzbekistan Cotton Research Institute |
Khasanova F.,Uzbekistan Cotton Research Institute |
And 3 more authors.
Agronomy Journal | Year: 2011
Limited or no tillage with residue retention on the soil surface has had mixed success in irrigated agricultural systems. The effects of tillage and crop residue management on soil properties and crop yields were studied on a silt loam soil using a rotation of winter wheat (Triticum aestivum L.) and maize (Zea mays L.) for 2 yr, followed by cotton (Gossypium hirsutum L.) for 2 yr. Permanent beds (PB) with limited reshaping and conventional tillage (CT) were compared, each with both 25% residue retention on a mass basis (R25) and 100% residue retention (R100). There was greater soil compaction and consolidation in the 0.2- to 0.3-m depth with the PB system regardless of residue retention practice. Compared with the CT system and the PB+R25 treatment combination, the PB+R100 treatment combination increased the amount of water-stable macroaggregates, however only in the fourth year. The soil organic C in the 0- to 0.4-m depth increased at 0.70 Mg ha -1 yr -1 in PB+R100 vs. 0.48 Mg ha -1 yr -1 in CT+R100. Poor early plant growth and reduced plant population in PB caused decreased water use efficiency (WUE) and irrigation water use efficiency (IWUE) of maize and cotton grown consecutively in 2006 and 2007. Generally, R100 improved IWUE and WUE, except for cotton in 2007. For PB+R100, cotton seed-lint IWUE in 2008 increased to 0.59 kg m -1 from 0.41 earlier. Smaller maize and cotton plant populations and cooler soil temperatures at cotton emergence in PB+R100 decreased crop productivity during the first 3 yr. © 2011 by the American Society of Agronomy. All rights reserved.