Came Through Drippin

Most of the world relies on flood irrigation to water crops. A more efficient alternative hasn’t been widely adopted because it’s so expensive. One Israeli soil physicist has the answer: a tiny plastic widget

- By Elizabeth G. Dunn

On the bone-dry western flank of Arizona, where the Colorado River Basin meets the Mojave Desert, sit 11,000 acres of alfalfa, sorghum, wheat, and Sudan grass belonging to the Colorado River Indian Tribes (CRIT), all destined to be harvested and sold for animal feed. For anything to grow here, irrigation is a must. Less than a quarter inch of rain has fallen so far this year, according to Josh Moore, who manages the farm on behalf of his tribe.

“The reservation is set up on a pretty outdated flood irrigation system,” Moore says. A network of canals built in the 19th century delivers water from the Colorado River, a system that seemed like a better idea before the watershed entered a persistent and increasingly dire state of drought. Although the canals supply enough water to meet CRIT’s farming needs for now, the tribes are planning for a hotter, drier future. This season, black plastic tubing can be seen snaking down hundreds of rows of sorghum: an experiment with microdrip irrigation that could radically reduce the farm’s withdrawals from an overtaxed watershed.

Around the world, most crops depend on rain alone for their water, but in places where rainfall isn’t sufficient, we’re forced to irrigate. Despite all the innovation that’s made its way into agriculture in recent years, from GPS-guided tractors to genetically engineered seedlings, 85% of all irrigation is still done by releasing vast quantities of water across the surface of a field, pretty much the same way it was handled 4,000 years ago in Mesopotamia.