Ten years of research indicates that a water management strategy can save rice producers money on fuel and conserve water without hurting yields.

Joe Massey, a scientist with the Mississippi Agricultural and Forestry Experiment Station and professor in Mississippi State University’s Department of Plant and Soil Sciences, has focused his career on water conservation in agriculture.

With funding from the Mississippi Rice Promotion Board and Mississippi Water Resources Research Institute, Massey worked with other MAFES researchers and rice growers to determine if intermittent flooding could work in Mississippi, as it does in Asia.

“These Mississippi farmers flood their rice fields and then let the floodwaters naturally subside,” Massey said. “When saturated mud is exposed in the upper half of the paddy, they pump back to a full-flood depth of about four inches. Growers using this method might pump water onto their fields only every five to nine days, depending on weather and soil conditions.”

By allowing the water level in the paddies to decrease, growers can better capture rainfall.

“One grower using intermittent flooding in 2011 subjected his field to eight wetting and drying cycles, resulting in substantial savings of water and fuel,” Massey said. “For every inch of rainwater that is captured or groundwater that is not pumped, farmers save about one gallon of diesel fuel per acre.”

For large operations, such savings can add up to tanker truckload quantities of fuel.

“Typically we get 10 to 14 inches of rain during the growing season in the Mississippi Delta,” Massey said. “If rice paddies are completely filled, there is no room to capture rainfall -- it rains, and the water runs off. Runoff may carry away nutrients and other chemicals that are expensive to purchase, and it may also contaminate our streams and rivers.”

Massey said even partial adoption of intermittent flooding can save producers money on energy and can relieve stress on those producers who struggle to maintain their rice crop when other crops also need watering.

Massey has studied how intermittent flooding affects both yield and quality.

“To date, rice yields on intermittently flooded fields have been the same or slightly higher, and milling quality has been unaffected when compared to rice that is continuously flooded,” he said. “We’ve tested this water management strategy on up to 15 rice varieties in replicated trials in production-scale fields on different farms.”

These results rely on producers’ use of multiple- or side-inlet irrigation, where irrigation is distributed to each paddy through plastic tubing.

Massey said when producers combine intermittent flooding with multiple-inlet irrigation, average water use has been close to that of zero-grade rice fields. Intermittent flooding helps maximize rainfall capture and reduce over-pumping, while multiple-inlet irrigation distributes water to each paddy individually.