Regulated Deficit Irrigation

Goldhamer calls the week-long study the greatest professional experience and research accomplishment of his 30-year water management career.

"Aerial Imagery Future of Water Management" Western Farm Press August 5, 2009

I've been reading about new methods for tightly controlling irrigation to minimize water use and salt buildup in the soil. Here's a brief description of regulated deficit irrigation (RDI) from the website of the California Agricultural Water Stewardship Initiative:

Deficit (or regulated deficit) irrigation can maximize water use efficiency by maintaining or increasing yields per unit of irrigation water applied. In deficit irrigation, the crop is exposed to a certain level of water stress for certain periods or throughout the whole growing season. The expectation is that yield reduction will be insignificant compared to the benefits gained from decreasing water use. However, deficit irrigation may only work for certain crops and the grower must have prior knowledge of crop yield responses to deficit irrigation. One of the greatest obstacles to implementing deficit irrigation is the wide range of crops that one grower may manage in any given season in California. More research on deficit irrigation forspecific crops and soils is needed to ensure guidelines for implementation are successful.

One of the challenges encountered in managing RDI is that plant stress needs to be monitored to avoid long-term crop damage. A piece in the Western Farm Press reports on a recent joint study done by David Goldhamer of UC Davis and scientists from the University of Cordoba in Spain. Dr. Goldhamer has been researching plant stress measurement for some time, and he was intrigued by that ability of the Spanish drone aircraft and their specialized infrared cameras to measure canopy temperatures. This general approach has been attempted in the past using satellites, but the low-flying drones made possible a degree of resolution which has previously eluded researchers.

I think that we can expect to see tremendous progress in the next few years in the efficiency of irrigation. As water becomes more valuable and land damage through overapplication of water becomes more obvious, technological advances like RDI will become increasingly attractive.