WUE

Water Use Efficiency (WUE) is a measure of how effectively water is converted into useful output, commonly used in agriculture, hydrology, and environmental sciences. In agronomy, WUE is typically defined as the ratio of crop yield to the amount of water used, and is often expressed as kilograms of yield per hectare per millimeter of evapotranspiration (kg ha−1 mm−1) or as kilograms per cubic meter of water (kg m−3). A common formulation is WUE = yield / ET, where ET is crop evapotranspiration, the combined loss of water through transpiration and soil evaporation.

WUE is context-dependent and can be influenced by crop type, management, and environment. A higher WUE does not automatically mean less water is used overall or that yield is maximized; it reflects efficiency in converting water into product under specific conditions. WUE estimates can vary with how ET is measured or modeled, making cross-crop or cross-region comparisons challenging.

Measurement methods for WUE include direct lysimetric measurements, soil-water balance approaches, and remote sensing-assisted estimates of ET. WUE is often used to guide irrigation planning, drought adaptation, and water resource management. It can also be considered in breeding programs aimed at improving drought tolerance or water productivity.

Strategies to improve WUE include optimizing irrigation timing and amount (such as deficit or regulated deficit irrigation), adopting precision irrigation technologies (drip or micro-irrigation), mulching and soil moisture conservation, improving soil structure, and selecting cultivars with higher water-use efficiency under target conditions.