Stage‐Specific Crop Coefficients for Cotton in Central India: A Comprehensive Analysis

ABSTRACT The estimation of water requirement for specific climatic conditions is a challenging but inevitable need for saving unnecessary water losses, and it becomes irrepressible in semi‐arid regions. Development of crop coefficient (Kc), the ratio of crop evapotranspiration (ETc) to reference evapotranspiration (ET O ), can enhance ETc estimates in relation to specific crop phenological stages. This research was conducted to determine growth‐stage‐specific Kc and crop water use for cotton ( Gossypium hirsutum ) in the Marathwada region (Central India). The FAO Penman‐Monteith equation was used to calculate ETo using data of meteorological variables from a nearby standard Meteorological Observatory, while ETc was measured using a weighing lysimeter installed near the centre of a cotton field seeded with cotton, as in the rest of the surrounding field. The average daily ETc of cotton over the complete growing season was figured out as 3.8, 4.0, and 3.7 mm day −1 in 2019, 2020 and 2021, respectively. The values ranged from 1.26 to 7.32 mm day −1 in 2019, 1.7 to 8.8 mm day −1 in 2020 and 1.3 to 7.3 mm day −1 in 2021. For early, mid‐season, and end‐of‐season phases of cotton, respectively, stage‐specific K c values averaged over 3 years were 0.51, 1.24 and 0.95. The computed Kc values differed significantly from the reported FAO‐56 values. This result can be useful for agricultural planning and efficient irrigation management and provides precise water applications for cotton cultivation in semi‐arid areas.