Soybean Water Requirement Calculator
Work out the seasonal and per-irrigation water requirement of soybean (FAO-56 ETc = ET₀ × Kc, peak Kc 1.15) for your field, climate, soil and irrigation method.
If irrigation is available, the flowering and pod-filling stages give the biggest response; a single life-saving irrigation in a dry spell at pod-fill can rescue a rain-fed crop. Avoid waterlogging at emergence.
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 Water Requirement Calculator to turn the FAO-56 crop coefficients for soybean into a real seasonal water volume and an irrigation interval for their own field — no agronomy tables, works offline.
About Soybean Water Requirement Calculator
Soybean needs 450–700 mm, mostly rain-fed in India, with pod-fill being the stage where a protective irrigation pays best. This calculator uses the FAO-56 method — crop evapotranspiration ETc = ET₀ × Kc — with soybean's own crop coefficients (Kc 0.4 initial, 1.15 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 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 Soybean Water Requirement Calculator?
- ✓Uses soybean'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 need?+
Soybean needs 450–700 mm, mostly rain-fed in India, with pod-fill being the stage where a protective irrigation pays best. 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.
Does soybean need irrigation?+
Most Indian soybean is kharif rain-fed, but a protective irrigation during a monsoon break at flowering or pod-fill prevents major yield loss. Where assured irrigation exists, scheduling to those stages gives the best return.
How much water does soybean use?+
About 450–700 mm over 90–110 days. The calculator sums ET0 × Kc across stages (Kc mid ~1.15) and, for irrigated crops, suggests an interval from your soil's water-holding capacity.
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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