SIU scientists share studies on nutrient management, water quality at IFB Field Day

The Field Day was sponsored by SIU College of Agricultural Sciences, Illinois Nutrient Research and Education Council and Illinois Farm Bureau.

By Kay Shipman

Southern Illinois University (SIU) researchers recently updated farmers on nutrient management and water quality studies, highlighting impacts of excessive rain and flooding.

SIU College of Agricultural Sciences sponsored the Field Day on Universities Farm along with the Illinois Nutrient Research and Education Council (NREC) and Illinois Farm Bureau.

Lauren Lurkins, IFB director of natural and environmental resources, shared IFB’s efforts and financial support for county nutrient management projects as well as work at the state and federal levels on water quality issues.

Keeping nutrients in fields

Studies show some cover crops release nitrogen quicker than others in southern Illinois, reported Karl Williard, professor of watershed management and hydrology. Williard is studying hairy vetch preceding corn and cereal rye preceding soybeans.

“In this climate, hairy vetch breaks down quicker than we had hoped. What happens to the nitrogen (within the vetch)? This year, with all the rain, there was a potential for nitrogen loss,” Williard said.

Farmers using hairy vetch as a cover crop may want to consider planting into “green hairy vetch” and closing the window between cover crop termination and planting, according to Williard. In comparison, cereal rye, a great nitrogen scavenger, can accumulate up to 40 pounds of nitrogen per acre “and is going to break down more slowly,” he said, making it a good candidate in areas with water quality issues.

Williard and Jon Schoonover, hydrology professor, are studying cover crops’ influences on sedimentation on a watershed scale. Their study shows cover crops reduced soil loss by 31% on a watershed scale.

“Even during storms, we’re getting more water infiltration (in fields with cover crops),” Williard said. Measurements show a 43% difference between fields with cover crops and those without.

However, the same watershed studies did not find changes in water quality. “We think it will take time,” Williard said. “It could be five to 10 years until we see those impacts.”

Schoonover shared information about innovative saturated buffers installed on a Moultrie County farm in March. Recently he installed water sediment control basins in the Lake Springfield Watershed, but had no research data to report.

Assessing nitrogen management, losses

With corn research plots planted mid-June, 2019 is proving a challenge for nitrogen study, Amir Sadeghpour, soil management professor, told farmers. Sadeghpour is working with Joshua McGrath, an agricultural soil management specialist with the University of Kentucky. The two scientists have 700 plots spread across Carbondale, Belleville and Kentucky.

With NREC funding, their goal is to develop precise nitrogen recommendations for specific field and crop conditions for a given year. “We are already accurate (with nitrogen recommendations), but we need different data if we want to be precise,” McGrath said.

Their project involves 45 nitrogen rates. “Can we tell you how much yield you get from starter fertilizer? How much from sidedress applications?” McGrath asked.

Sadeghpour also is studying the use of cover crops and no-till to improve yields and reduce nitrogen losses and nitrous oxide emissions.

“The main goal is to identify which cover crops and which system gives the best results,” Sadeghpour told farmers.

His study involves corn and soybean plots with three treatments of vetch, an oat-radish mixture and no cover crops. Tillage and no-till systems are used on both cover crops and the no-cover crop plot.

To date, the no-till plots with a vetch cover crop have resulted in the highest nitrogen losses. Sadeghpour speculated vetch should be terminated after corn planting because the cover crop relates nitrogen so quickly.

His goal is to examine systems and learn where nitrogen is leaching to determine if there is a tradeoff of nitrous oxide losses in the air instead of nitrogen losses in water.