The Adoption of Best Management Practices to Reduce Agricultural Water Contamination

agricultural drainage water
Agricultural drainage water

The Adoption of Best Management Practices to Reduce Agricultural Water Contamination

Every summer, a "dead zone" is formed in the Gulf of Mexico. The plumes of oxygen-robbing algae, fed by excess nitrogen from the Mississippi River, destroy marine life and threaten the livelihoods of those living in the Gulf. The states bordering the Mississippi River are developing strategies to reduce nitrogen from agricultural areas, surface runoff, and wastewater treatment plants. In a new study, scientists at the University of Illinois have estimated that a new conservation practice known as saturated buffers can reduce nitrogen by 5 to 10 percent from agricultural drainage.

New protection practices can limit nitrogen pollution in the agricultural drainage water

Reid Christianson, co-author of the study, published in Agricultural and Environmental Letters and a research assistant professor at the University of Illinois in the Department of Crop Sciences, said "It may not seem very much, because agricultural drainage is only part of the nitrogen entering the Mississippi River, but from 5 to 10 percent is very good for an inexpensive, passive system that farmers could put in and forget about."
The saturated buffers are plant strips from the ground - not more than 30 feet - between the dried-up agricultural fields and the waterways. Typically, tile pipes that carry drainage water from empty fields are directly in streams or ditches. With a saturated buffer, the water is redirected to a perforated tube running below the surface and parallel to the current and stream. The water then flows through the soil from the saturated reservoir in the stream. Along the way, soil microbes naturally remove up to 44 percent of nitrogen.

"The saturated buffers do not leave much of the land out of production, and they are fairly cheap at $ 3000 to $ 4,000 to treat drainage from a field-sized area. Farmers must be prepared not to farm right up to the creek, but conservation practices are on the edge. “I believe that saturated barriers are easily adapted to agriculture and provide additional benefits such as pollinator habitat and wildlife, said Laura Christianson, co-author of the study and assistant professor also in the crop sciences department.

To arrive at nitrogen reduction estimates, Christianson and doctoral student Janith Chandrasoma observed the stream and soil types and the publicly available digital maps of crops to calculate the total number of saturated buffers that can be set up in the Midwest: 248,000 to 360,000, which can treat up to 9.5 million Acres of dried land. With other studies showing average nitrogen removal rates between 23 and 44 percent, this number of saturated storage devices will reduce total nitrogen load by 5% to 10% in agricultural drainage.

This approach requires many assumptions. For example, there are no satellite images or maps for tile drainage systems throughout the Midwest, so researchers have assumed that corn or soybean fields on the soil were portrayed as "poorly drained". However, under the many corn and soybean fields in the Midwest, read notes tile drainage systems have been installed, not only the poor drainage ones." Upon the whole, our assumptions were relatively very conservative. So we underestimate our statistics as a result," said Laura.

Saturated buffers are the new conservation practices with the first natural resource conservation service standard that had been published in 2016. So far, they have not been adopted anywhere according to the scale shown in the study of Christianson. For example, Laura estimates that at present there are less than 50 saturated buffers in the entire Midwest region. “The probability of adopting the scale on which we estimate on paper is very long, but we can do anything to reduce the nitrogen flowing in the Gulf, Especially if it fits relatively easily at the attention of warrants and agricultural management practices,” said Laura.

The study report, has been published in Agricultural and Environmental Letters, with the title "Saturated buffers: What is their potential impact across the US Midwest?". Authors of the study include Reid Christianson, Janith Chandrasoma and Laura Christianson, all of them belong to the Department of Crop Sciences in the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois. For this research, it was funded by USDA Farm Service Agency.

Journal Reference:
Agricultural and Environmental Letters, Jan. 3, 2019; DOI: 10.2134/ael2018.11.0059

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