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Is Treated Wastewater The Future Of Irrigation?

  In June, Bernd Leinauer, New Mexico State University professor and extension turfgrass specialist, and Elena Sevostianova, post-doctoral research associate, were approached by the United Nations Food and Agriculture Organization and travelled to Rome, Italy, after their research on effluent water was published and garnered the attention of the scientific community worldwide.

“We published a paper about tailored treated effluent water. Our suggestion was that it could be one of the main water sources in the future when it comes to irrigating the landscape or producing agriculture. The paper hypothesizes whether or not it poses a risk to the environment,” Leinauer said. “Of course our background is on turfgrass and therefore we use it as our model crop. Our approach is to leave the nitrogen in the water for plants to use it.”

Their research states that “using such tailored water to irrigate turf areas would reduce or eliminate the need for additional mineral fertilizers if concentrations of nitrate in the water were raised during the growing season to meet the annual nitrogen requirement of the crop or plant.”

Leinauer explained that leaving nitrogen in the water concerns growers because the content in the effluent water used for irrigation may exceed the plants’ demands and pollute ground water, but he noted that most of the nitrogen is removed at the treatment plant. 

“Our perspective in the paper is that removing nitrogen is unnecessary when you apply the water during the main growing season because most growers or turf managers will also apply fertilizer. However, the application of fertilizer costs money and the production of fertilizer leaves a significant carbon footprint.” he said. 

NMSU’s Agricultural Science Center at Tucumcari has been researching the use of effluent water on crops for two years because drought halted the center’s research. 

In 2012, Leonard Lauriault, superintendent, made a 20-year contract with the city of Tucumcari to use treated wastewater produced by the city to irrigate the fields at the center. 

Projects are conducted annually using treated water, but it could take four or five years or more for studies to become conclusive. Many aspects need to be assessed such as the types of weeds that will grow in treated wastewater, the types of crops and how the water will impact the soil and the environment. 

Leinauer said dealing with public perception is the biggest obstacle in using effluent water around homes for landscape irrigation and growing food, although there are strict regulations on the use of affluent water. 

“Most of the public does not object if the effluent water is used in parks or golf courses, but when it gets closer to home, on our backyards for example, that’s when people have a problem,” he explained. “Our approach proposes that we use effluent water in our backyards.”

He proposes to use decentralized water treatment systems, giving each subdivision its own treatment plant, and using subsurface irrigation instead of sprinklers. This prevents human exposure to the irrigation water.

His approach and proposals have garnered the attention of other countries that are experiencing drought and population growth. During his stay in Rome, he talked to the leaders of FAO’s agricultural and irrigation divisions about the possibilities of using effluent water in urban and agricultural settings in arid or semi-arid areas of the world. 

“I was really flattered and honored to be invited. It was definitely an eye opening experience,” he said. “We learned about the problems other people in the world are facing, particularly in northern Africa where new urban areas are developing and face exactly the same problems we are facing. These cities need to develop strategies to deal with the effluent water. This is why they became interested in our research. This gives it a much broader application to what we propose.”

Leinauer said that there is a possibility for collaboration in the future to help other countries in places like Africa to help resolve their water issues.

“The work we do is not just specific to New Mexico,” he added. “ It is relevant to other areas in the U.S. and any country that has a similar climate.”

Information from NMSU