BELLEVILLE — Farmers have a lot of questions about water quality. Researchers at Southern Illinois University are hoping to provide some answers.
Increasing concern about nutrient loss and watershed contamination is driving solutions across the Midwest, with many farmers looking for proactive approaches to keeping fertilizers on the farm and out of waterways.
Farmers and ag advocates are well aware of legislation regulating fertilizer application in some regions of the country, such as the Chesapeake Bay. The lawsuit by the Des Moines Water Works that targeted nitrate use was ultimately dismissed, but it has put the ag community on notice that nutrient loss strategies are necessary going forward.
“These water quality concerns are going to be here a long time; they’re not going anywhere,” said Jon Schoonover, a water quality specialist at SIU. “We’re looking at impending nutrient water quality standards. We’re trying to help farmers come up with defense mechanisms.”
To that end, Schoonover and colleagues are taking a close look at methods including cover crops, bioreactors and saturated buffers.
The university has established a working field in Massac County, near the Ohio River, with a saturated buffer system. A number of tile outlets were installed earlier this year with the goal of reducing nitrate runoff.
The structure consists of two lateral lines, 500 feet downstream and 500 feet upstream. Permanent vegetation borders the stream. A series of stop logs — adjustable elements that control water levels in a field — are part of the system.
The water level in a field can be raised, allowing water containing nitrogen to saturate the wooded vegetation, reducing nitrate flow into the stream.
“A two-stage buffer is what we’re proposing,” Schoonover told growers at a field day here. “The control structures have three chambers. We’re reducing the output of the water to the stream. Not only that, but the plants assimilate the nitrogen.”
The researchers plan to monitor the project for up to four years. An economist will also do a full budget analysis.
Water quality specialists are also examining the effects of cover crops. Graduate student Gurbir Singh has spent the past three years studying the role of legumes and non-legumes in fixing nitrogen.
“If there is no cover crop in fall, we have more nitrogen in the soil, and that nitrogen has potential to be lost into the water,” Singh said. “If you delay the termination date of legumes by two weeks to a month, it delays your planting date, but you get the benefit of fixing nitrogen.”
Singh and his team followed corn harvest with cereal rye in September to determine whether the rye would take nitrogen from the soil and improve water quality.
“That’s what we saw. When there are no cover crops, there’s more N leaving,” he said. “Cover crops do work. They help in fixing that N into their biomass and make it potentially available in the crop.”
Another consideration is moisture absorption. Use of sensors showed soils in which cereal rye was planted had “significantly” more moisture in the spring. On the other hand, hairy vetch showed significant transpiration of water.
“There’s a potential benefit for this type of cover crop to get N, but it eats up your moisture,” he said. “You could plant it on areas of a field that get waterlogged.”