Using Modified Atmometers (ETgage) for Irrigation Management

Estimation of evapotranspiration for specific crops (ETc) is important for irrigation scheduling and agricultural water management. ETG can be used as a tool to schedule irrigation. ETc for crops such as corn and soybean can be estimated using an equation that takes into account evapotranspiration of the reference crop and Kc, a "crop coefficient" adjustment factor. ETr is usually estimated using equations that take into account weather variables such as solar radiation, air temperature, wind speed, and relative humidity. Kc mainly depends on the type of crop and its growth stage, and can be adjusted to account for a reduction of ETc when the crop is under water stress or an increase in evaporation when the soil surface is wet due to rain or irrigation. There are several models of ETG, depending on whether readings are taken manually or are automatically recorded.