Does efficiency save water? A field experiment with Spanish irrigators

Whether technology can be used to decouple agricultural productivity from intensive water use depends on a behavioural assumption that has never been directly tested: that farmers will conserve water when efficiency improves rather than expand production. We test this assumption through a field experiment with 105 real irrigators in Spain, using a repeated dictator game in which participants decide how to allocate a water endowment between irrigation and conservation. After a five-round baseline an efficiency shock is introduced, raising the return per unit of water from €1 to €1.50, mimicking an increase in irrigation productivity. In two additional treatments, we observe behavioural change when water savings go to the community versus the environment, and the behavioural implications of including a fixed cost of technology. Results show that on average farmers do increase water savings following the efficiency shock by 7 percentage points, well short of the 33% required by the zero-rebound benchmark, thus yielding an average rebound of 79.8%. Overall, participants save more water under environmental framing, which consistently outperforms community framing. Moreover, results show how fixed technology costs substantially reduce rebound estimates, suggesting that standard calculations ignoring modernisation costs systematically overestimate behavioural offset. Critically, our results show that rebound is strongly heterogeneous across farmer types: high initial water users respond significantly more to the efficiency shock, saving more water, while low initial users, analogous to deficit irrigators, prioritise income recovery over conservation. We argue that rebound measured solely by water withdrawals is an incomplete policy metric, and that a useful assessment of technology must make policy goals explicit, account for technology costs, and accommodate farmer heterogeneity.

The seminar series is organized by the Section Economics of Wageningen University (consisting of the groups Agricultural Economics and Rural Policy, Development Economics, Urban Economics, Environmental Economics and Natural Resources, and Economic and Environmental History).

The seminar is aiming to foster the exchange on recent topics in the field of economics. We consider contributions from all fields of economic research and invite speakers from Wageningen, the Netherlands and abroad.

The seminar is organized as a weekly lunch seminar taking place on campus. Meetings are between 12:00 and 13:00 hours. Lunch is served. 

All staff and students are welcome!