Liquid Gold

Improving water quality in pastures and irrigation efficiency in row crops

By: Vanessa Beeson

Liquid Gold

Furrow irrigation, using polypipe to flow water down crop rows, is a common agricultural practice throughout Mississippi, particularly in the Delta. (Photo by David Ammon)

Water resources are at historic lows across the American West where water wars rage between states like California, Arizona, and Nevada, over the coveted Colorado River Basin. In the South, a decades-long water conflict continues between Georgia, Florida, and Alabama over the Apalachicola-Chattahoochee-Flint Basin. At home, the price of water for Americans climbed more than 30% in the last decade. Water sustains us—from fresh drinking water to irrigation for the crops we eat—a resource we take for granted is becoming increasingly coveted. Some may say that water, in its role for sustaining life, is becoming more precious than gold.

Mississippi leads the nation in dependence of ground water—84 percent of our freshwater supply comes from groundwater according to the American Geosciences Institute—and much of that comes from the Mississippi River Alluvial aquifer. While Mississippi producers might not have the same challenges growers in western states face, the Mississippi River Alluvial aquifer still loses about 300,000 acre-feet a year. MAFES scientists are working on multiple fronts to address water issues in the state. This feature looks at two of those efforts: ensuring efficient crop irrigation and clean water in agricultural and managed landscape systems by filtering stormwater runoff.

Improved Irrigation

The Mississippi River Alluvial Plain spans Mississippi, Louisiana, Arkansas, Tennessee, Kentucky, and Missouri. More than nine billion gallons of groundwater are pumped from aquifers across the region each day. Much of the pumping is from the Mississippi River Alluvial aquifer and is used for irrigation and agricultural production.

Dr. Drew Gholson, coordinator of the National Center for Alluvial Aquifer Research (NCAAR), said nearly 22,000 permitted wells draw 370 million cubic meters of water a year from the Mississippi River Alluvial aquifer alone. He said many farm acres in the Delta are irrigated and much of that is drawn from the Mississippi River Alluvial aquifer.

"NCAAR's mission to conduct research and provide information for issues surrounding water use for agriculture and natural resources in the Lower Mississippi River Basin," he said.

The assistant plant and soil sciences professor and MAFES scientist grew up in a farming community in North Texas along the Red River and developed a passion for water conservation as a graduate student at Texas A&M. He is focused on several projects focused on improving irrigation efficiency across the Delta.

NCAAR is a cooperative program between the USDA's Agricultural Research Service and MAFES. Current NCAAR projects aim to improve water use efficiency; develop more water efficient cropping systems; and find ways to improve water capture, irrigation, and distribution systems.

"Our goal is to help farmers become more efficient from an irrigation standpoint. Eighty percent of irrigation in the Delta is furrow irrigation. There are a lot of reasons for that. The Delta is flat so we can create precision level fields with gravity-fed irrigation. That coupled with a high production aquifer makes furrow irrigation a popular choice for the region," he said.

He said the fact that water wells can pump at a high rate can be a hindrance with farmers not necessarily realizing the need to conserve water.

"We have models that show the aquifer is being depleted but from a pumping standpoint if you're getting a high rate of water being pumped out, it can be difficult for a farmer to see it as a limited resource," he said.

He hopes to evaluate farmer perception when it comes to the importance of saving water. A study published in 2020 in Agronomy, in which Gholson was a co-author, analyzed data from 2016 that indicated a third of Mississippi growers who irrigated and participated in the survey were unaware of groundwater problems at the state and farm levels.

"We learned that this lack of awareness is related to whether farmers noticed a change in the depth to water distance in their irrigation wells," Gholson noted.

In the years since, as more growers adopt best practices in irrigation efficiency, Mississippi has become one of the leading states, second only to Nebraska, which has most widely adopted soil moisture sensors.

"We've been conducting research on soil moisture sensors and computerized hole selection and as we share this research with the farmers, more of them are learning and are willing to adopt the practices that work. Using less water saves them money in the long run, too," he said.

On the horizon, Gholson looks forward to emerging research in automated irrigation technologies. An on-farm experiment conducted in 2020-2021 evaluated automated irrigation on corn and soybeans. Each site included nearby irrigation wells and fields, and one site served as a control while the other was equipped with pump controls, actuated valves, and soil moisture sensors enabled with telemetry options and programmed irrigation time. Information on irrigation application, pumping energy requirement, crop growth, and yield was collected. Automated corn and soybean fields had a decreased total water use of 30-40% compared to their respective controls. The automated corn field had higher yield than the control and the soybean automated field and control were roughly the same in yield.

"That study suggests that irrigation automation may be a beneficial tool for soybean and corn irrigation, saving water and time and ultimately conserving groundwater in the Midsouth," Gholson said.

Gholson and his team are also examining sustainable production systems to improve water resources in the Lower Mississippi River Basin.

"From a national standpoint, cover crops and reduced tillage systems are being adopted with more frequency. Sometimes, however, a system that works well in the Midwest might not be the best fit for the Midsouth or the Mississippi Delta," Gholson said. "Our job is to try and figure out how to incorporate these conservation systems in this area. We're analyzing timing of cover crop planting and termination and documenting insecticides and herbicides, and nutrient and sediment runoff in these systems to better understand what a sustainable production system looks like for our area."

Gholson also said it remains vital that research reflect topics farmers are most interested in, so the team continues to administer surveys that capture farmer perceptions.

"Knowing which irrigation advancements and technologies farmers are adopting helps drive our research. If they're willing to adopt one thing over another, we can focus there because that's what they're telling us they want to know more about. At the same time, we can monitor the success of new innovations," he said.

Gholson said he is most inspired when the team develops a practice farmers can immediately use.

"Farmers have to make a thousand daily decisions so our goal is to find straight-forward solutions they can implement quickly and easily," he said.

Cleaner Creeks

Dr. Tim Schauwecker, professor in the Department of Landscape Architecture, is focused on improving water quality in pasture systems. The project was born out of a multi-college collaboration between the College of Agriculture and Life Sciences, the College of Arts and Sciences, and the Bagley College of Engineering. The work aims to reduce phosphorus and the potential for algal blooms in the Red Bud-Catalpa Creek watershed, which covers 45.2 square miles in and around Starkville. The creek is part of a larger system, the Tombigbee River Basin, which ultimately drains about 6,100 square miles.

Schauwecker, along with Dr. Todd Mlsna, professor in the Department of Chemistry, and Dr. John Ramirez-Avila, associate professor in the Department of Civil and Environmental Engineering, sought to mitigate stormwater runoff in the watershed. Specifically, the research is taking place at the MAFES Bearden Dairy Research Center, where Catalpa Creek runs through the farm. The team seeks to determine if engineered biochar and slag reduce phosphorus and improve water quality on the farm.

Schauwecker explained how cows accessing the stream can degrade a stream's water quality.

"Cows will create paths down into the creek, which erode and form gullies. This can lead to rainwater, sediment, and nutrients washing out into the stream. We're addressing the runoff in those gullies to stabilize the stream system within the pasture," he said.

The team planted a conservation buffer along a section of the stream cows previously accessed. They planted 10 feet that is growing into forest and an additional 25 feet of grasslands beyond that. Within the buffer, they designed 18 sites in gullies near the stream: six check dams with slag only, six check dams with slag and biochar, and six controls. The engineered biochar and electric arc furnace (EAF) slag both function as bioreactors adsorbing, or pulling, phosphorus from the water.

"The chemistry department engineers the surface of the biochar so that from a water chemistry standpoint, it's able to grab elements out of the water you don't want in there, like phosphorus. The charge of the surface of the biochar is positive, so it attaches to negatively charged ions such as phosphorus. The slag, a coproduct of steel that's like a metallic gravel, also has the same properties to adsorb the phosphorus," Schauwecker explained.

Schauwecker said that phosphorus in stormwater runoff has detrimental effects on water quality and ecosystem health when it reaches surface waters and promotes algal blooms.

"Phosphorus is important in terms of water quality because a certain ratio of nitrogen and phosphorus will lead to algal blooms," he said.

The field level study has been evaluated in lab and mesocosm scale settings.

"A mesocosm scale study was conducted outdoors over a 12-month period to evaluate the effectiveness of three filter materials in their ability to adsorb phosphorus, retain water, and support plant life. The filter materials examined were EAF slag, engineered biochar, and sand. All treatments demonstrated positive plant response and the ability to retain water. The EAF slag and biochar removed significant amounts of phosphorus," Schauwecker explained.

Scientists will monitor the sites over the next three years as part of a Natural Resources Conservation Service Conservation Innovation Grant.

"Our hope is to develop best practices that farmers and landowners can use to achieve improved water quality and prevent algal blooms in streams and rivers," he said. "You can have sustainable agricultural production and good water quality. Best management practices are how we try to obtain both."

Travis Zimber, MSU College of Business alumnus, oversees regional slag sales for Levy Corporation. Levy contracts with Columbus-based Steel Dynamics to produce slag, which Levy donated for the project. Zimber discussed slag's growing role in environmental solutions.

"The use of EAF slag to reduce phosphorus is growing, especially in the Upper Midwest. It's new for us in this region and I think the MSU team is doing an excellent job. I've seen the research in the field. Anything we can do to help, we're happy to jump on board," he said.

Schauwecker said he's most excited about the educational opportunities and the cross-college collaboration.

"It's rare for three colleges to collaborate on something like this. Also, we had the opportunity to host Bailey Bullard, a visiting undergraduate researcher from the University of North Georgia who was funded to spend the summer here by the National Science Foundation, through a program in partnership with the MSU chemistry department that provides undergraduate students research training," he said, noting that Bullard is now working on her master's in chemistry at Mississippi State.

Schauwecker said the team's next goal would be to figure out how to scale the system for on-farm implementation.

"One of the ultimate goals is to scale this up. We've gone from 100 grams of biochar and slag to a cubic yard at a time and we're trying to figure out if the cost is feasible. If it is, it could be a small intervention that shows landowners what they might do to be a part of managing water resources within the watershed," he said.

Collaborators on Improved Irrigation include MAFES scientists Dr. Himmy Lo, assistant extension and research professor in MSU Department of Agricultural and Biological Engineering, and Dr. Nico Quintana, assistant research professor in MSU Department of Agricultural Economics. Funding partners include USDA ARS and the Environmental Protection Agency.

Collaborators on Cleaner Creeks in addition to Schauwecker, Mlsna, Ramirez-Avila, and Bullard include Casey Johnson, research associate in the MSU Department of Landscape Architecture; Lorena Chavarro, master's student in the Department of Civil and Environmental Engineering; and CeCe Marascalco, landscape architecture master's student. Scotty Coffman, farm supervisor, contributed to site construction. Funding is through an NCRS Conservation Innovations Grant and Seattle-based Biochar Solutions donated materials in addition to Levy Corporation.

Our hope is to develop best practices that farmers and landowners can use to achieve improved water quality and prevent algal blooms in streams and rivers. You can have sustainable agricultural production and good water quality. Best management practices are how we try to obtain both.

Dr. Tim Schauwecker

Dr. Tim Schauwecker (right), and Dr. John Ramirez-Avila, show a piece of slag to students in the field. (Photo by David Ammon)

Dr. Tim Schauwecker (right), and Dr. John Ramirez-Avila, show a piece of slag to students in the field. (Photo by David Ammon)