Lucerne Water Requirement Calculator
Work out the seasonal and per-irrigation water requirement of lucerne (alfalfa) (FAO-56 ETc = ET₀ × Kc, peak Kc 1.2) for your field, climate, soil and irrigation method.
Irrigate after each cut and at 10–20 day intervals in the dry season; lucerne's deep roots let it tolerate longer gaps than shallow fodders. Avoid waterlogging, which kills the crown and thins the stand.
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 Lucerne Water Requirement Calculator to turn the FAO-56 crop coefficients for lucerne (alfalfa) into a real seasonal water volume and an irrigation interval for their own field — no agronomy tables, works offline.
About Lucerne Water Requirement Calculator
Perennial lucerne is a heavy water user (1000–1500 mm/year over many cuts) but its deep taproot makes it efficient and drought-resilient between irrigations. This calculator uses the FAO-56 method — crop evapotranspiration ETc = ET₀ × Kc — with lucerne (alfalfa)'s own crop coefficients (Kc 0.4 initial, 1.2 mid-season, 0.9 late) across a 270-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 Lucerne 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 Lucerne Water Requirement Calculator?
- ✓Uses lucerne (alfalfa)'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 lucerne (alfalfa) need?+
Perennial lucerne is a heavy water user (1000–1500 mm/year over many cuts) but its deep taproot makes it efficient and drought-resilient between irrigations. The exact figure depends on climate and season length; this tool sums ET₀ × Kc across the crop's 270-day growth stages for your conditions.
How much water does lucerne need?+
About 1000–1500 mm a year spread over its many cuts across 3–4 years. Its very deep taproot makes each irrigation go far, but total use is high because the perennial keeps growing whenever conditions allow.
How often to irrigate lucerne?+
Typically after each cut and every 10–20 days in dry weather. The deep root system tolerates longer intervals than shallow fodders, but the stand thins if waterlogged or if the crown stays wet.
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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