Actual and predicted evapotranspiration along with groundwater contribution for wheat (Triticum aestivum) crop.

This experiment aimed to determine the crop evapotranspiration (ETc) and groundwater input in total water used by wheat (Triticum aestivum) crop and to use the CROPWAT model to predict the crop ETc. To estimate the on-field ETc and groundwater contribution, the combining lysimeter technique was used. The water levels below the soil surface were kept at 1.60, 2.20, and 2.80 m and each water table depth was replicated three times. A field experiment was conducted under silt loam (SL) and silty-clay loam (SCL) soil conditions. The climatic parameters and water balance components were recorded accordingly. The on-field ETc was compared with the predicted ETc by CROPWAT model. Under SL soil, the observed ETc was 442, 427 and 401 mm and under SCL soil conditions it was observed as 419, 402 and 389 mm at the water table depth of 1.60, 2.20, and 2.80 m, respectively. The ETc was reduced with an increase in water level below the surface. The groundwater contribution under SL and SCL soil was observed as 50%, 41%, and 30% and 43%, 34%, and 24%, at 1.60, 2.20 and 2.80 m water table depth, respectively. The predicted ETc by CROPWAT model for SL and SCL soil conditions was 428.8 and 410.7 mm, respectively. The projected ETc was equal to the average ETc observed under lysimeter experiment. Thus, the use of CROPWAT model is recommended to overcome waterlogging and salinity problems and to conserve water resources. Considering lysimeter results, the irrigation applications must be revised for shallow water table levels due to adequate contribution of groundwater. [ABSTRACT FROM AUTHOR]