Pigeonpea Water Requirement Calculator
Work out the seasonal and per-irrigation water requirement of pigeonpea (arhar) (FAO-56 ETc = ET₀ × Kc, peak Kc 1.05) for your field, climate, soil and irrigation method.
Pigeonpea rarely needs irrigation in the monsoon but responds to a protective irrigation at flowering and pod development in dry spells. Its very deep roots make waterlogging — not drought — the bigger risk.
Indicative planning figures based on published research averages. Local soil tests, varieties and weather change actual requirements — confirm with your agronomist or extension officer.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Farmers and irrigation planners use the free Pigeonpea Water Requirement Calculator to turn the FAO-56 crop coefficients for pigeonpea (arhar) into a real seasonal water volume and an irrigation interval for their own field — no agronomy tables, works offline.
About Pigeonpea Water Requirement Calculator
Long-duration arhar is mostly rain-fed, needing 450–600 mm, with its deep taproot tapping moisture other crops cannot reach. This calculator uses the FAO-56 method — crop evapotranspiration ETc = ET₀ × Kc — with pigeonpea (arhar)'s own crop coefficients (Kc 0.4 initial, 1.05 mid-season, 0.4 late) across a 160-day season. Pick your climate band (which sets reference ET₀), irrigation method (drip, sprinkler, pivot or surface — each with its own efficiency) and soil texture, and it returns the seasonal water need in cubic metres, the peak daily demand, the net depth per irrigation and how many days to wait between irrigations.
How to use Pigeonpea Water Requirement Calculator
- 1Enter your field area and choose the climate band matching your season.
- 2Select your irrigation method and soil texture.
- 3Read the seasonal water volume, peak daily demand and irrigation interval, then follow the scheduling note.
Why use Pigeonpea Water Requirement Calculator?
- ✓Uses pigeonpea (arhar)'s real FAO-56 Kc curve, not a flat factor
- ✓Accounts for drip / sprinkler / pivot / surface efficiency
- ✓Gives seasonal volume, peak daily need and an irrigation interval
- ✓Free, instant and fully in-browser — works offline in the field
Frequently asked questions
How much water does pigeonpea (arhar) need?+
Long-duration arhar is mostly rain-fed, needing 450–600 mm, with its deep taproot tapping moisture other crops cannot reach. The exact figure depends on climate and season length; this tool sums ET₀ × Kc across the crop's 160-day growth stages for your conditions.
Does pigeonpea need irrigation?+
Mostly rain-fed, but a protective irrigation at flowering or pod development during a dry spell prevents flower drop and lifts yield. Its deep taproot otherwise mines subsoil moisture through the long season.
Why is waterlogging dangerous for arhar?+
Pigeonpea is highly sensitive to waterlogging — even short periods of standing water kill roots and cause wilt. Good drainage matters more than irrigation frequency for this deep-rooted, drought-hardy crop.
What is ET₀ and Kc?+
ET₀ (reference evapotranspiration) is how fast a standard grass surface loses water in your climate. Kc (crop coefficient) scales it to a specific crop and growth stage. Crop water use ETc = ET₀ × Kc — the basis of FAO-56 irrigation scheduling.
Is this calculator free and private?+
Yes — free, no sign-up, and all calculation runs in your browser, so it works offline in the field and your data never leaves the device.
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