MIRI Method Reduces Water Use In Rice Field Tests

Rice, one of the world’s most important foods, is a labor-intensive crop that also requires plenty of water. Often, water pumped to flood rice fields comes from shallow aquifers that are dwindling.

The ARS-developed system, called multiple-inlet rice irrigation, or MIRI, involves laying disposable, thin-walled, polyethylene irrigation tubing to connect rice paddies as they are flooded with water. Currently, most rice fields are flooded by discharging water directly into the highest paddy and allowing water to overflow into lower paddies.

Earl Vories, an agricultural engineer at the ARS Cropping Systems and Water Quality Research Unit’s satellite location in Portageville, Mo., has been working with colleagues in the unit and with extension engineer Phil Tacker and others at the University of Arkansas Cooperative Extension Service to study water requirements for rice on a commercial production scale.

Their on-farm water use studies from the1999 through 2002 growing seasons consisted of 14 paired fields located close together, with the same cultivar, soil type, planting date, and management practices. The MIRI method required an average of 24 percent less irrigation water than conventional paddy flooding.

Reducing irrigation water on MIRI fields is important to rice farmers for more than just water and energy savings, since rice fields often share a water supply with other crops. The amount of water available to irrigate these other crops usually depends on how much water is used to first adequately irrigate the rice. A 24 percent reduction in the rice crop's water usage could mean higher yields for the other crops.