Determination of Evapotranspiration and Optimum Irrigation Schedule for Cotton in Çukurova Region Using CROPWAT Model

Usman Muhammad Umar; Burak Şen; Zeynep Ünal

Determination of Evapotranspiration and Optimum Irrigation Schedule for Cotton in Çukurova Region Using CROPWAT Model

2025

Usman Muhammad Umar | Burak Şen | Zeynep Ünal

The agriculture sector is actively looking for the most effective ways to manage water resources. Proper water management is crucial for increasing agricultural productivity and optimizing the region’s water usage efficiency. The purpose of this study was for estimating the irrigation water requirement, reference and crop evapotranspiration and irrigation schedule for cotton in Çukurova region over a 31-year period (1990-2020) using the CROPWAT model. To ensure appropriate water utilization and planning, information regarding the climate data was obtained from the Adana station of Turkish State Meteorology Service. The soil and crop data were sourced from Turkey’s directorate of agricultural research and policies. The dates, amounts, effective rainfall, net irrigation requirement (NIR), and yield decrease for rainfed and different irrigated conditions were all calculated using the CROPWAT 8.0 model. The findings indicated that the average reference evapotranspiration (ETo), crop evapotranspiration (ETc) for cotton and effective rainfall were 918.9 mm, 809.5 mm, and 149.4 mm respectively. It was also estimated that the dates of irrigation after planting (DAP) were 72 days, 101 days, 131 days and 170 days. The total quantity of water utilized for irrigation throughout the growing season at critical depletion and user defined were 700 mm and 545 mm respectively, thus 155 mm of water was saved (22%). Data of maximum crop yield obtained at critical depletion by CROPWAT was associated with data from Turkish Statistical Institute (TUIK) (2014-2020) and TUIK data is compared with CROPWAT data which was estimated under rainfed condition. According to the result 51% of yield reduction was simulated when irrigation was not applied.

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