Evaluating evapotranspiration and crop coefficients of onion (Allium cepa L.) using monolithic weighable lysimeters with two contrasting textured soils

In recent times, the significance of effective water resource management has been on the rise due to the impacts of climate change.Improving crop productivity and optimizing water resource management necessitate precise evaluations of water balance and crop coefficients (K c ).The crop coefficients are defined as the ratio of crop evapotranspiration (ET c ) to reference evapotranspiration (ET o ), and it is essential for accurately determining the water requirements of the crop.This research focused on analyzing water balance, including evapotranspiration and precipitation, throughout the growth stages of onions through using weighable lysimeters.Additionally, this study presented crop coefficients and water requirements for growth stages.Onion was cultivated repeatedly for 2 years in two upland soils with different soil textures.As a result of analyzing the water balance, there is comparable total inflow volumes between the two soil types, with sandy loam exhibiting a higher overall outflow rate.The crop coefficients for the growth stages were determined as 0.67, 0.77, 0.97, 0.99, and 0.84, respectively.The assessment of water requirement for two-year cultivation indicated a lower requirement compared to a normal year.The precise evaluation of water balance in Korea through weighable lysimeter and the formulation of national factors are anticipated to enhance the prediction accuracy of field crop water management in the future.