Soybean Deficit Irrigation Calculator
Work out the seasonal and per-irrigation water requirement of soybean (deficit) (FAO-56 ETc = ET₀ × Kc, peak Kc 0.9) for your field, climate, soil and irrigation method.
Deficit irrigation works only if you protect the critical reproductive stage and take the cut from tolerant vegetative phases. It maximises yield-per-drop, not yield-per-hectare — best when water, not land, is the limit.
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 Soybean Deficit Irrigation Calculator to turn the FAO-56 crop coefficients for soybean (deficit) into a real seasonal water volume and an irrigation interval for their own field — no agronomy tables, works offline.
About Soybean Deficit Irrigation Calculator
Deficit irrigation deliberately under-waters drought-tolerant stages to stretch limited supply across more area — modelled here at ~75% of full ETc. This calculator uses the FAO-56 method — crop evapotranspiration ETc = ET₀ × Kc — with soybean (deficit)'s own crop coefficients (Kc 0.4 initial, 0.9 mid-season, 0.5 late) across a 120-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 Soybean Deficit Irrigation 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 Soybean Deficit Irrigation Calculator?
- ✓Uses soybean (deficit)'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 soybean (deficit) need?+
Deficit irrigation deliberately under-waters drought-tolerant stages to stretch limited supply across more area — modelled here at ~75% of full ETc. The exact figure depends on climate and season length; this tool sums ET₀ × Kc across the crop's 120-day growth stages for your conditions.
What is deficit irrigation?+
Applying less than full crop water requirement on purpose, concentrating the limited supply on the most sensitive growth stage and accepting mild stress at tolerant stages. It maximises production per unit of water across a larger area.
When does deficit irrigation make sense?+
When water — not land — is the binding constraint, and the crop has stress-tolerant phases. You spread a fixed water supply over more hectares, raising total farm output even though per-hectare yield dips slightly.
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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