Calculate water use efficiency as crop yield per unit of water applied. Compare WUE across crops, seasons, and irrigation methods in bu/ac-in.
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 calculator computes WUE from your yield and water-applied data and lets you compare two scenarios side by side to evaluate the impact of different irrigation strategies. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process. This tool handles all the complex arithmetic so you can focus on interpreting results and making informed decisions based on accurate data.
In areas where water is scarce or expensive, maximizing WUE is as important as maximizing yield. This tool helps you track and compare water productivity to guide irrigation investment and cropping decisions. Having a precise figure at your fingertips empowers better planning and more confident decisions. Manual calculations are error-prone and time-consuming; this tool delivers verified results in seconds so you can focus on strategy.
WUE = Yield (bu or lbs/ac) / Water Applied (in) WUE can also be expressed per acre-foot: WUE (bu/ac-ft) = Yield / (Water in / 12)
Result: WUE = 9.1 bu/ac-in
WUE = 200 bu/ac ÷ 22 inches = 9.09 bu/ac-in. This means each inch of water produced about 9.1 bushels of corn per acre. Well-managed irrigated corn in the Midwest typically achieves 8–12 bu/ac-in.
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.
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.
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.
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.
It should. Total water applied for WUE should include irrigation plus effective rainfall. Otherwise you underestimate the water used and overestimate irrigation efficiency.
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.
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).
Soil type, variety, planting date, fertility, pest pressure, irrigation timing, and weather all influence yield and water use. Even adjacent fields can differ significantly.
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.