Most farmers believe that conserving water and reducing fertilizer and herbicide inputs in an intensively managed crop like rice can have a positive effect on the environment. But how do they quantify the benefit?

Fortunately, the U.S. Department of Agriculture’s Agricultural Research Service has a team of scientists who have been working toward that goal, placing complicated instruments on cooperating farms in the Arkansas Rice Belt.

Michele Reba, research hydrologist and acting research leader at the USDA-ARS Delta Water Management Research Unit, which is located at Arkansas State University, discussed that work in her welcome to the 24th annual Arkansas Soil and Water Education Conference and Expo. The event was held online this year.

“First off, the mission of the Delta Water Management Research Unit is the preservation of water, quantity and quality for agriculture,” said Reba, who has been a member of the ASWEC Steering Committee for the past 10 years. “We have been working closely with area producers and other collaborators, including private companies and state and federal agencies.

“Our research aims to improve agricultural production and natural resources that sustain yield and grain quality while reducing inputs and environmental risks.”

The unit has three scientists – Reba, Joe Massey and Arlene Adviento-Borba, both of whom are research agronomists. Massey was instrumental in developing the multiple inlet rice irrigation or MIRI and alternate wetting and drying concepts of irrigating rice while working at Mississippi State University.

“My research efforts are focused on water management and water availability,” Reba said. “I use instruments that are able to measure a field integrated flux of water, carbon dioxide and methane.

Fluctuation measurement

These instruments are able to measure these fluxes year-round; provide an evaluation at a systems level; and don’t simply focus on the production season.

“We are working to answer questions regarding rotation, residue management and winter flooding on the water quality side. I have water quality instrumentation that contribute to statewide and nationwide networks aimed at understanding how field management impacts excess nutrients and sediment loss in runoff while sustaining yield and limiting inputs.”

Her team is also working to implement the first-ever case study of artificially adding water back to the declining alluvial aquifer in the Delta region of Arkansas.

“We are working closely with producers, universities and state and federal agencies to determine the utility of using managed aquifer recharge in the Arkansas Delta.”

Recent research from Massey has focused on irrigation automation “because he believes that further refinements in irrigation water management will require advances in irrigation automation technologies,” she said.

“As part of this effort, he’s developing a rice irrigation system called automatic early cascade irrigation shutoff, or AECIS, that may conserve water on par with multiple inlet rice irrigation. Joe is also working with Arkansas State University researchers to further our understanding of the impact cover crops have on production.”

Also on the acronym front Massey is working on new programs to help transfer research findings to producers. One example is his development of the rice HAWGG or helping agriculture with greenhouse gases and the rice WOLFE or working on lowering field emissions programs in collaboration with Riceland Foods Inc.

“The purpose of these programs is to promote a voluntary single dry down event to reduce methane emissions from Arkansas rice without increasing nitrous oxide.”