By 2025, the Illinois Nutrient Loss Reduction Strategy calls for a 15% reduction in nitrate in Illinois rivers and streams compared to levels that existed in 1997-2011. The graph below shows the sources of nitrate contributions (Urban Runoff, Point Sources and Non-Point Sources).
For the non-point sector, which includes agriculture, a 15% reduction in nitrate loss equates to 50 million pounds of nitrogen, or 25,000 tons of nitrogen.
Can we meet this goal by 2025 with voluntary actions? We believe we can, by following these BMPs:
- For corn acres, use the MRTN (Maximum Return to Nitrogen) rate recommendation. It is based on actual nitrogen rate and corn yields, over a multitude of years and varying environmental conditions. It is the best recommendation that exists to ensure farmers do not overapply or underapply nitrogen to get the best return on their nitrogen investment. Using the MRTN to reduce excess nitrogen in the agricultural system is the first activity on the INLRS list of recommended practices to reduce nitrogen losses.
- Split your nitrogen applications. Take the rate recommended by the MRTN and split it with at least two different timings of nitrogen application. That way, no matter what happens with rainfall or drought, not all of your nitrogen is susceptible to loss at once. That can mean a fall application with N-Serve after soil temperature falls to 50 degrees at the 4 inch level, followed by a spring or side-dress application, or an early spring application followed by a side-dress application. Be cautious about applying nitrogen too late in the season; NREC research in 2016 showed that nitrogen applied late in the growing season did not increase yields over nitrogen applied earlier in the season. Remember that nitrogen that is not used by the plant is susceptible to loss to the environment. We learned that lesson in the drought of 2012, when corn was not able to take up applied nitrogen due to lack of water. That nitrogen was later lost to the water systems in early spring 2013, when it finally rained and moved the unused nitrogen out of the soil and into lakes.
- Consider a cereal rye cover crop following corn, and ahead of soybeans. NREC research performed by Lowell Gentry at the Douglas County site is showing that cereal rye after corn will reduce nitrogen loss through field tile compared to fields with no cover crop. Plus, cereal rye ahead of soybeans is not negatively impacting soybean yields and can provide other soil benefits as well.
In summary, using a cover crop after corn and ahead of soybeans, along with following the 4Rs for corn will help us make progress toward meeting the 15% reduction goal by 2025 if we can get more acres adopting these voluntary methods.
IFCA is assisting NREC in 2017 with research on the most effective way to use cover crops ahead of corn. The picture (right) here was taken by Jason Solberg of IFCA in mid-April. At this site, the cereal rye is being terminated on three different dates; corn is being planted in cereal rye that was killed the day prior. This research site is also studying different nitrogen treatments in the cover crop/corn system along with cover crop biomass analysis and sampling of ammonium and nitrate levels in the soil throughout the season.
What about the Phosphorus Goals of the INLRS? The INLRS also calls for a 25% reduction in phosphorus losses by 2025. The majority of phosphorus reductions will come from the point source sector, which plans to meet this goal ahead of schedule by implementing new technologies to remove phosphorus from the waste water systems. By 2025, the non-point sector must reduce phosphorus losses by 4,480,000 million pounds or 2,240 tons. It is not as significant of a task as reducing nitrogen losses in terms of millions of pounds, but it is just as important.
Agriculture can help meet the phosphorus loss reduction goals with these BMPs:
- No application of phosphorus fertilizers or manure on soils that exceed maintenance levels based on current soil tests;
- Use reduced till or no-till;
- Plant cover Crops;
- Install buffer strips to protect streams, ditches and waterways to reduce soil loss.
For more information please contact IFCA at (309) 827-2774 or email Dan Schaefer, IFCA’s Director of Nutrient Stewardship: email@example.com.