Quantifying and Comparing Crop Water Productivity in Organic vs. Conventional Iceberg Lettuce, Yuma, AZ

This study quantified Crop Water Productivity (CWP) in organic and conventional iceberg lettuce systems at the University of Arizona Yuma Agricultural Center during the 2024–2025 season. Both systems were managed under subsurface drip irrigation using sensor-based and traditional irrigation scheduling strategies. Results showed that conventional lettuce produced about 40–50% more yield per unit of crop evapotranspiration than the organic system; this difference may be related to differences in crop growth and nutrient availability. While short-term CWP was higher under conventional management, organic systems may enhance soil structure, water-holding capacity, and infiltration over time; however, these soil changes were not measured in this single-season study. Sensor-based irrigation scheduling in most cases improved irrigation water-use efficiency across both systems, demonstrating that precision irrigation technologies can help Yuma growers make better use of water resources. Combining precision irrigation with organic farm practices that focus on soil management and improving soil properties offers a promising path toward sustaining productivity and conserving water in Yuma’s desert agriculture.