This tool helps farmers and agronomists calculate daily water loss from soil and crops to plan irrigation schedules. It uses local weather data to estimate evapotranspiration for better crop management. Accurate ET calculations support efficient water use and improved yields in farming operations.
Evapotranspiration (ET) Calculator
ET Results
Enter data and click Calculate to see results.
How to Use This Tool
Enter the average temperature, relative humidity, wind speed, and solar radiation for your location. Select your crop type from the dropdown to apply the appropriate crop coefficient. Choose your preferred unit for the results and click Calculate to see daily, weekly, and monthly evapotranspiration estimates.
Formula and Logic
This tool uses the FAO Penman-Monteith equation to calculate reference evapotranspiration (ET₀), which is then adjusted by a crop-specific coefficient (Kc). The formula considers temperature, humidity, wind speed, and solar radiation to estimate water loss from a standardized grass surface. The crop factor scales this reference value to match specific crop water needs.
Practical Notes
- Seasonal factors: Adjust crop coefficients based on growth stages—seedling, vegetative, flowering, and maturity phases require different water amounts.
- Soil conditions: Sandy soils drain faster and may need more frequent irrigation than clay soils; consider soil moisture sensors for accuracy.
- Yield variability: ET calculations help optimize water use to reduce yield gaps caused by drought or over-irrigation.
- Pest and disease impact: Proper irrigation scheduling based on ET can reduce humidity-related diseases like fungal infections.
- Equipment costs: Using ET data can lower pumping costs by avoiding unnecessary irrigation, saving on fuel and maintenance.
Why This Tool Is Useful
Accurate ET calculations enable farmers to apply water precisely when and where it's needed, conserving resources and improving crop health. This supports sustainable agriculture by reducing water waste and energy use. Agronomists and farm managers can use these estimates for planning irrigation systems and budgeting water resources.
Frequently Asked Questions
What if my weather data is incomplete?
If you lack solar radiation or wind data, use local weather station averages or estimate based on historical patterns. The tool will still provide a reasonable ET estimate, but accuracy improves with complete data.
How often should I recalculate ET?
Recalculate daily during peak growing seasons, as weather conditions change. For long-term planning, use weekly or monthly averages to adjust irrigation schedules.
Can this tool be used for livestock water needs?
While primarily for crops, ET data can inform livestock water planning by estimating pasture water loss. For direct livestock needs, combine with animal-specific water intake calculators.
Additional Guidance
For best results, calibrate the tool with local field observations. Integrate ET data with soil moisture monitoring for precision irrigation. Consult local agricultural extension services for region-specific crop coefficients and weather data sources.