Evapotranspiration, fiber yield and quality, and water productivity of cotton (Gossypium hirsutum L.) under different irrigation technologies in a semiarid climate

Cotton is a relatively new crop in southern Kansas and its effective irrigation scheduling requires information on crop water requirement and water productivity in a given climatic condition. This study aimed to: (1) assess cotton crop actual evapotranspiration, irrigation water requirement, (2) evaluate lint yield and quality, and (3) determine the water productivity related to total water (irrigation and rainfall), irrigation, and evapotranspiration under different irrigation technologies and rainfed conditions in semi-arid climate of western Kansas. Field experiments were conducted in 2020, 2021, and 2022 at the Southwest Research and Extension Center (SWREC) in Garden City, KS, to evaluate cotton production under four irrigation technologies which were low elevation spray application (LESA), low energy precision application (LEPA), mobile drip irrigation 1 (MDI1 with 3.79 L/h), mobile drip irrigation 2 (MDI2 with 7.57 L/h) and a rainfed treatment under a randomized complete block design with the variety PHY 205 W3FE. Crop management was similar across all treatments for three growing seasons. The results showed that the seasonal actual evapotranspiration (ETa) varied among the irrigation technologies, the rainfed treatment, and years. On average, LESA recorded the highest ETa value of 463.9 mm and LEPA had the lowest ETa value of 457.2 mm. The lint yield and lint quality (micronaire, length, strength, uniformity, color grade) varied significantly among the irrigation technologies and the rainfed setting. The highest lint yield of 1061.94 kg ha(-1) was obtained under LEPA, while the rainfed registered the lowest lint yield of 224.13 kg ha(-1). The irrigated cotton had a high value for lint quality parameters with the LEPA having the best lint quality. Furthermore, on average, LEPA recorded the highest evapotranspiration-water, total-water, and irrigation-water use efficiencies, and the values were 0.23, 0.33, and 0.39 kg m(-3), respectively. The cotton ETa and water productivity are valuable parameters for effective irrigation scheduling for cotton production under similar climate and soil conditions.