Evapotranspiration Calculator
Calculate crop water requirements and optimize your irrigation schedule
Calculate ET and Irrigation Needs
About Evapotranspiration
Understanding Evapotranspiration
Evapotranspiration (ET) is the combined process of water evaporation from soil and plant transpiration. It represents the total water requirement of crops and is essential for determining irrigation schedules. Accurate ET calculations help optimize water use, reduce costs, and improve crop yield.
ET Components
ET consists of two main processes that work together to remove water from agricultural systems.
Reference ET (ET0)
Evapotranspiration from a well-watered grass reference crop, representing water demand based on climate conditions alone.
Crop ET (ETc)
Actual evapotranspiration of a specific crop, calculated by multiplying ET0 by the crop coefficient (Kc).
Factors Affecting ET
- Temperature: Higher temperatures increase evaporation rates
- Humidity: Lower humidity increases water loss to the atmosphere
- Wind speed: Wind removes moist air, increasing evapotranspiration
- Solar radiation: More sunlight increases water demand
- Crop type and growth stage: Different crops and stages have different water requirements
- Soil moisture: Available water influences crop transpiration
Using ET for Irrigation Planning
Use ETc values to schedule irrigation by calculating daily water loss and applying water when soil depletion reaches 50-60% of available water. Account for rainfall and soil water storage capacity. Monitor weather changes as ET varies seasonally and daily. Adjust irrigation frequency and duration based on crop growth stages, soil type, and weather conditions.
Important Note
This calculator uses the FAO-56 Penman-Monteith method for ET0 estimation. Actual irrigation requirements depend on local soil characteristics, rainfall patterns, and agronomic practices. For best results, validate calculations with local weather station data and consider consulting agricultural extension services for your specific region.