Southeast Department of Agriculture Studies Arsenic Levels in Rice Irrigation Methods

CAPE GIRARDEAU, Mo., March 2, 2016 – The Southeast Missouri State University Department of Agriculture’s irrigation comparison study has seen positive results for maintaining rice yield production and reducing arsenic concentrations.

The research is part of a continuing effort by the Department to examine the differences between furrow and delayed flood irrigation in rice production. Dr. Michael Aide, chair of Southeast’s Department of Agriculture, and his team looked at the nitrogen efficiency and arsenic uptake rates between the two irrigation systems.

“We found between 44 different varieties of rice that the yields for furrowed irrigated rice are comparable if not better than the traditional delayed method because of improvements in water application timing, nitrogen management and weed control,” said Aide. “An important consequence of converting is that the normal and safe concentration of arsenic in tradition irrigation systems virtually disappears with furrow irrigated rice.”

In furrow irrigation, or row irrigation, farmers flow water through their crops down small, parallel trenches running in the direction of a predominant slope. In the traditional delayed method, water is introduced to the field from a ditch or pipe and simply flows over the ground through the crop and ponds the water between three to six inches.

Over four growing seasons, the Department collected data indicating that arsenic concentrations were significantly smaller in rice from furrow irrigations systems.

Arsenic is a natural component of the earth’s crust but is a major toxic pollutant in its inorganic form. The World Health Organization and the U.S. Environmental Protection Agency has established a maximum daily intake of inorganic arsenic and sets the limits in drinking water to 10 micrograms per liter. Long-term exposure from food and drinking water with unsafe arsenic levels can cause serious health issues, including cancer, skin lesions, cardiovascular disease and neurotoxicity.

Rice produced under the traditional delayed irrigation method contains arsenic levels well within the international trade guidelines and is considered completely safe to consume, but there’s always room for improvement, said Aide.

Arsenic levels in “Missouri rice are low to begin with but furrow irrigated rice is even lower,” he said. “If you switch to furrow irrigated rice, it’s virtually undetectable.”

Additionally, farmers growing rice may also choose to use the furrow irrigation system because it uses less water than the traditional method, said Aide.

With farmers not only in the Delta region but also across the nation looking for ways to conserve water, how they manage the water that is available is a driving force behind which irrigation method they choose.

There is one caveat though.

“Furrow irrigation does take more expertise,” said Aide. “It takes more time to watch your fields, manage your water, attend to weed issues and assess your nitrogen efficiency.”

But the data the Department has collected has larger implications for how rice producers choose to grow their rice in the future.

“Furrowed irrigated rice avoids arsenic uptake, it’s essentially arsenic free and we have the supporting data,” said Aide.

With high expectations from consumers demanding safer food products, the decisions start in the fields.

Southeast has one of the only consistent programs for furrow irrigated rice for the Mid-South region. It has partnered with the Fisher Delta Research Center, the University of Missouri Extension and the Missouri Rice Council which also have furrow irrigation projects to help distribute the information and knowledge to local farmers and rice producers.

“I think southeast Missouri is showing great interest in converting to a furrow irrigated rice regime,” said Aide.

The department will continue to calculate and compile data to include more acres and more varieties of rice. As producers switch irrigation methods, the data will be vital for insurance coverage, he said.

Photo Caption: Dr. Michael Aide (right) with Southeast President Dr. Carlos Vargas (front) and Dr. Chris McGowan (behind), dean of the College of Science, Technology and Agriculture.