Dan Porges/Peter Arnold Observatory In an effort to make irrigation more efficient — to obtain more “crop per drop” — farmers have adopted alternatives to flooding and other conventional methods. Among these is drip irrigation, shown above, in which water flows only to the roots. Drip systems are costly, but they save much water. Or do they? A hydrologic and economic analysis of the Upper Rio Grande basin in the Southwest, published in The Proceedings of the National Academy of Sciences, suggests that subsidies and other policies that encourage conservation methods like drip irrigation can actually increase water consumption. “The...
