Cotton irrigation scheduling improvements using wetting front detectors in Uzbekistan

Authors: IBRAGIMOV, NAZIRBAY - Uzbekistan Institute Of Cotton Breeding And Seed Production; AVLIYAKULOV, MIRZOOLIM - Uzbekistan Institute Of Cotton Breeding And Seed Production; DURDIEV, NORMAT - Uzbekistan Institute Of Cotton Breeding And Seed Production; Evett, Steven - Steve; GOPPOROV, FARRUHJON - Uzbekistan Institute Of Cotton Breeding And Seed Production; YAKHYOEVA, NAFISA - Uzbekistan Institute Of Cotton Breeding And Seed Production

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2020
Publication Date: 10/1/2020
Citation: Ibragimov, N., Avliyakulov, M., Durdiev, N., Evett, S.R., Gopporov, F., Yakhyoeva, N. 2020. Cotton irrigation scheduling improvements using wetting front detectors in Uzbekistan. Agricultural Water Management. 244. Article 106538. https://doi.org/10.1016/j.agwat.2020.106538.
DOI: https://doi.org/10.1016/j.agwat.2020.106538

Interpretive Summary: Furrow irrigation is still used on approximately 12% of Southern Great Plains irrigated land and typically has an irrigation efficiency of less than 60% (only 60% of water applied can be used by the crop) compared with greater than 90% efficiency of current sprinkler irrigation systems and greater than 95% efficiency of subsurface drip irrigation systems. Efforts to improve furrow irrigation efficiency have met with limited success. In cooperative research with scientists in Uzbekistan, ARS scientists from Bushland, Texas, studied devices called wetting front detectors (WFDs) to see if they could determine when the soil at the bottom of the rooting depth had approached field capacity as a means to reduce runoff and deep percolation losses and increase the crop productivity per unit of water applied. In all three years of the study, runoff, deep percolation and volume of irrigation water applied were less when WFDs were used. Both total seed-lint cotton yield and the yield per unit of water applied were increased with the use of WFD, which indicated that excessive irrigation that occurred under normal practices was depressing yield. The WFDs were outfitted with radios that sent signals to a WIFI router so that a computer monitor could alert the irrigation manager remotely to stop irrigations. Adoption of this technology should greatly improve irrigation efficiency where furrow irrigation is being used.

Technical Abstract: Previous research established growth-stage-specific irrigation scheduling for upland cotton (Gossypium hirsutum L.) in Uzbekistan. We report further investigation of irrigation scheduling for different cotton varieties and its effect on seed-lint yield and irrigation crop water productivity with and without use of a wetting front detector (WFD) to trigger irrigation cessation. Field trials were conducted in silt loam soil near Tashkent, Uzbekistan, in 2016, 2017 and 2018. The growth stages of germination to flowering, flowering to boll formation, and maturation were considered for development of irrigation scheduling regimes with respect to field capacity water content (Fc). The best growth, development and seed-lint yield for the Sultan cotton variety were achieved with irrigations scheduled at soil water content levels of 70, 75, and 65% of Fc during the aforementioned three growth stages, respectively, and were achieved for variety UzPITI-103 with irrigations scheduled at 70, 70, and 60% of Fc during the aforementioned plant growth stages, respectively. There were appreciable varietal differences in water requirement with the early maturing Sultan variety having a larger water requirement. In contrast, irrigation scheduling with larger Fc values did not result in increasing the yield for the UzPITI-103 cotton variety. In comparison with irrigation without WFD, the use of the WFD decreased irrigation duration by 2.0 to 3.5 hours, net irrigation amount by 7 to 90 m**3 per ha, irrigation run off by 69 to 134 m**3 per ha, and deep percolation below the root zone by 10 to 17 m**3 per ha, while increasing irrigation crop water productivity by 0.08 to 0.10 kg per m**3 and seed-lint yield by 0.04 to 0.10 Mg per ha. Irrigation scheduling regimes based on percentages of Fc and irrigation with WFD should be considered applicable practices for upland cotton varieties on silt loam soils of the central zone of Uzbekistan and for similar soil-climatic conditions of Central Asian countries.