Maize Water Requirement Calculator
Work out the seasonal and per-irrigation water requirement of maize (grain) (FAO-56 ETc = ET₀ × Kc, peak Kc 1.2) for your field, climate, soil and irrigation method.
Never let maize stress at tasseling and silking — that fortnight decides the cob. Knee-high and grain-fill irrigations come next in priority. Avoid waterlogging; maize is sensitive to it.
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 Maize Water Requirement Calculator to turn the FAO-56 crop coefficients for maize (grain) into a real seasonal water volume and an irrigation interval for their own field — no agronomy tables, works offline.
About Maize Water Requirement Calculator
Grain maize uses 500–700 mm, and the tasseling-to-grain-fill window is when even a brief moisture stress slashes yield the hardest. This calculator uses the FAO-56 method — crop evapotranspiration ETc = ET₀ × Kc — with maize (grain)'s own crop coefficients (Kc 0.3 initial, 1.2 mid-season, 0.5 late) across a 125-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 Maize 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 Maize Water Requirement Calculator?
- ✓Uses maize (grain)'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 maize (grain) need?+
Grain maize uses 500–700 mm, and the tasseling-to-grain-fill window is when even a brief moisture stress slashes yield the hardest. The exact figure depends on climate and season length; this tool sums ET₀ × Kc across the crop's 125-day growth stages for your conditions.
When is maize most sensitive to water stress?+
Tasseling and silking — the two weeks around flowering. Moisture stress then causes poor pollination and barren tips, the single biggest avoidable yield loss in maize. Grain fill is the next most sensitive stage.
How much water does a maize crop need?+
About 500–700 mm over 100–120 days depending on climate. The calculator sums ET0 × Kc across stages (Kc peaks near 1.2 at tasseling) and converts it to a seasonal and per-irrigation volume for your field.
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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