Sustainability Implications of Deficit Irrigation in a Mature Water Economy: A Case Study in Southern Spain

Deficit irrigation (DI) is an agricultural practice in which the volume of irrigation water applied during the crop cycle is below the irrigation requirements for maximum production, the aim of which is to increase irrigation water productivity. Most research on this technique has focused on agronomic strategies while the economic and environmental consequences have received little attention. This study aims to shed some light on this matter and presents preliminary results regarding the implications of DI with respect to the sustainable use of water resources. The analysis is based on the DPSIR analytical framework (Driving force/Pressure/State/Impact/Response) and the microeconomics of DI. The case study focuses on intensive olive groves in the Guadalquivir river basin in Southern Spain (where olive cultivation accounts for 50% of the total irrigated area). The analysis shows that the widespread use of DI practices, which is the farmers' response to a decreasing net water supply and falling farm incomes (driving force) in the context of a mature water economy, may help to break the DPSIR chain of causality, provided that there are restrictions on any expansion in irrigated area. They can, thus, play a role in achieving sustainable water use. Conversely, demand and supply (regulator) responses involving raising the price of water would lead to higher pressures on the resource and represent a negative driving force in our DPSIR model.