Water Use Efficiency (WUE) Calculator

About the Water Use Efficiency (WUE) Calculator

Water Use Efficiency (WUE) measures how much crop yield is produced per unit of water consumed or applied. It is typically expressed as bushels per acre-inch, pounds per acre-inch, or tons per acre-foot. Higher WUE means you are getting more production from every drop of water.

WUE varies by crop, variety, management, climate, and irrigation method. Comparing WUE across fields or seasons reveals which practices maximize production relative to water use — a critical metric in water-limited regions.

This page converts yield and applied water into a water-productivity number you can compare across fields, seasons, or irrigation strategies.

When This Page Helps

WUE matters when it changes how scarce water is allocated. This page gives a quick side-by-side number for that decision.

How to Use the Inputs

1. Enter the crop yield in bushels or pounds per acre.
2. Enter the total water applied (irrigation + effective rainfall) in inches.
3. Read the WUE in yield units per acre-inch.
4. Optionally enter a second scenario for comparison.
5. Compare WUE between scenarios to identify the more efficient practice.

Example Calculation

Tips & Best Practices

• Include effective rainfall in total water for a true WUE.
• Deficit irrigation can improve WUE but may reduce total yield.
• Corn WUE: 8–12 bu/ac-in; Wheat: 4–6 bu/ac-in; Soybeans: 3–5 bu/ac-in.
• Track WUE year-over-year to measure management improvements.
• Drip and LEPA systems often boost WUE by reducing non-productive losses.
• High WUE combined with high yield is the ultimate goal.

Improving WUE

Strategies to improve WUE include better irrigation scheduling (avoiding over-watering), selecting drought-tolerant varieties, optimizing plant population, improving soil health for better water-holding capacity, and using efficient irrigation methods like drip or LEPA.

WUE and Economics

Highest WUE does not always equal highest profit. Consider the marginal value of water: if additional water is cheap, applying more may increase total revenue even if WUE drops. In water-limited scenarios, maximizing WUE ensures every gallon contributes to production.

Benchmarking WUE

USDA and state extension services publish WUE benchmarks by crop and region. Compare your values to these benchmarks to identify improvement opportunities. If your WUE is significantly below the benchmark, investigate irrigation scheduling, system efficiency, and agronomic practices.

Frequently Asked Questions

• What is a good WUE for corn?

  Well-managed irrigated corn achieves 8–12 bu/ac-in. Top producers in favorable years may see 13–15 bu/ac-in. Dryland corn in semi-arid areas may be 5–8 bu/ac-in.

• Does WUE include rainfall?

  It should. Total water applied for WUE should include irrigation plus effective rainfall. Otherwise you underestimate the water used and overestimate irrigation efficiency.

• Can WUE be too high?

  Very high WUE often comes with deficit irrigation that sacrifices some yield. The economic optimum balances WUE with total revenue. Maximizing WUE alone may not maximize profit.

• How do I measure water applied?

  Use a flow meter on the pump, pivot speed and nozzle charts, or district delivery records. For rainfall, use a rain gauge and adjust for effective rainfall (roughly 75% of measured for light rains).

• Why does WUE vary between fields?

  Soil type, variety, planting date, fertility, pest pressure, irrigation timing, and weather all influence yield and water use. Even adjacent fields can differ significantly.

• What units are used internationally?

  Outside the U.S., WUE is often expressed as kg/m³. 1 bu corn/ac-in ≈ 5.7 kg/m³. The FAO typically reports in kg per cubic meter.