How is the irrigation interval calculated?

Irrigation interval (days) = MAD × TAW / ETc, where MAD is management allowed depletion (typically 40–50% for most crops), TAW is total available water = (FC - WP) × Zr × 1000 (mm), FC is field capacity, WP is wilting point, Zr is root zone depth (m), and ETc is daily crop evapotranspiration (mm/day). Per FAO Irrigation Paper 56.

What is the management allowed depletion (MAD) for different crops?

MAD represents the fraction of TAW that can be depleted before yield loss occurs. Values: vegetables 30–35%, potatoes 35–40%, corn 50–55%, wheat 55%, cotton 65%, sunflower 45–50%. Lower MAD = more frequent irrigation = higher water use efficiency but more operational complexity. Per USDA-NRCS National Engineering Handbook Part 652.

Irrigation Free Online Calculator and Tools

How It Works

Determine optimal irrigation intervals and application depths based on ET demand, soil water holding capacity, and crop rooting depth

Each component has a specific meaning:

ET demand — The et demand recorded for the patient or scenario being assessed.
Soil water holding capacity — The soil water holding capacity recorded for the patient or scenario being assessed.
Crop rooting depth — The crop rooting depth recorded for the patient or scenario being assessed.

Note: Interpret the irrigation scheduling result against the clinical thresholds and context described above.

How to Use

Enter the ET demand, soil water holding capacity, crop rooting depth for the patient or scenario you are assessing. Determine optimal irrigation intervals and application depths based on ET demand, soil water holding capacity, and crop rooting depth. Use the irrigation scheduling result to inform your clinical assessment.

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