Outdoor & Protected Cultivation
Rainfall, Irrigation & Water-Source Integration
Outdoor irrigation should account for effective rainfall, root-zone storage, runoff, evapotranspirative demand, and source-water quality. Rainfall amount alone does not reveal how much water actually reached the active root zone.
Key concepts
- Rain can run off, evaporate, or wet only part of the root volume
- Containers and raised beds respond differently from field soil
- Source-water chemistry can change through the season
- Repeated shallow irrigation can produce a different root distribution than deeper wetting
What to measure or observe
- Use a rain gauge or reliable local precipitation record
- Check moisture at root depth after rain
- Track irrigation volume and distribution
- Periodically characterize source water when it changes or symptoms suggest a need
Common mistakes
- Skipping irrigation because rain occurred without checking root depth
- Counting forecast rainfall as delivered water
- Ignoring seasonal source-water changes
- Watering only at the stem base as the root system expands
Visuals this lesson still needs
- Rainfall-to-root-zone water balance
- Container-versus-field wetting profile
- Seasonal water-source record
- Root-zone expansion irrigation map