Definition
Reference ET describes atmospheric evaporative demand for a reference surface. Crop ET adjusts demand for crop type and stage, typically using coefficients and management factors. ET is not a direct pump setting; it informs requirement calculations.
Why it matters
- ET anchors science-based irrigation planning.
- Ignoring climate demand leads to chronic over- or under-watering.
- Transparent ET assumptions improve professional review of schedules.
Interpretation priorities
- Know whether values are reference ET, crop ET or operational estimates.
- Check weather data quality and representativeness for the site.
- Combine ET with soil storage and system efficiency for practical schedules.
Management implications
- Update crop coefficients as phenology advances.
- Document weather sources used in planning.
- Validate model-based schedules with field observation.
Evidence discipline
Distinguish measured values, user assumptions, calculated outputs and interpretation. See the data & evidence policy and scientific platform for Flaha's authority posture.
Related solutions
Continue with a demonstration
Discuss how FlahaCALC can support this decision on your site, programme or laboratory workflow.