2 weeks Ago By Michael Johnson
SAUK RAPIDS, Minn. — A gathering of people from various backgrounds and expertise converged on the banks of the Mississippi River on Tuesday, April 15, to talk about nitrogen trends and reduction strategies. The meeting was the fifth annual Ag-Urban Partnership Forum put together by the Minnesota Board of Water and Soil Resources, the Minnesota Department of Agriculture, the Minnesota Department of Health, and the Minnesota Pollution Control Agency, along with the cooperation of agriculture, community and water partners.
This year's theme was nitrogen and brought together members of science, health, geology, hydrology, rural water, municipalities, education and policy. And among the about 60 in attendance were two or three farmers, including father and son, David and Mark Legvold, of Northfield, Minnesota. ADVERTISEMENT While many southern Minnesota farmers were out in force tilling up the land in preparation for planting, Mark Legvold said he planned to start planting soybeans that weekend using a strip tiller to plant into the cover crop-covered soil he planted following last fall's harvest.
No need for extra tillage passes, which has proven to be a cost savings. It was a method Brad Carlson , an educator with the University of Minnesota Extension, would have highly recommended as he spoke to the group about the abundance of nitrogen present in our air, soil and water. When there are excess amounts of nitrogen in soil, it can either be utilized by plants or it can be released into the ground or surface waters, where problems arise in supplying safe drinking water to nearby or far away residents.
When asked what farmers could be doing to limit the amount of nitrogen entering our drinking water sources, Carlson said a large part is not related to runoff or appropriate fertilizer application. “I think really the key is there’s roughly 3,000 to 5,000 pounds of nitrogen per acre tied up in our soil organic matter, and that's going to release through microbial process as long as it's warm and moist,” Carlson said. For most farmers in the state, from the time they harvest a crop in late summer or early fall, there are about seven weeks before the necessary heat in the soil exits and nitrification is no longer at work.
Cover crops could utilize that nitrogen during that time frame. So when Legvold Farms plants that cover crop to help protect their topsoil from blowing away, they are also putting down a crop that will take up excess nitrogen into the plant that may otherwise be lost as it moves down through the soil into groundwater. When the Legvolds terminate the cover crop in the spring, it continues to serve as a weed barrier as that corn or soybean rises up.
“And so a lot of the nitrogen that we find losing the system through drainage or into shallow groundwater is attributable to accumulations that happen after the growing season and it’s not the result of fertilizer applications,” Carlson said. The exception is over-fertilizing. ADVERTISEMENT “What’s really important for farmers is to just not be over-fertilizing,” Carlson said.
There are strategies to minimize loss of nitrogen, including the use of nitrification inhibitors, soil testing, water management and cover crops, which can add expenses on the farm. Using less nitrogen fertilizer would be a cost savings if it’s not a sacrifice to yield. Carlson drove home that the answer to the problem is not getting rid of the fertilizer, it’s zeroing in on the amount the crop needs.
To try to find out that key amount is the yearly battle that farmers must contend with. “Farming is a yearly process and we are learning something new every single year and we’re studying something new every single year,” Mark Legvold said. One thing new this year and for the next two years is a research project he is taking part in, where they are applying the standard nitrogen recommendations for achieving 200-bushel corn.
But an on-farm study will test soils to help them adjust those nitrogen levels and perform a side-by-side comparison. “That’s just part of the learning process that we go through every single year on the farm, where we’re trying to fine-tune and refine how we’re doing things to take good care of the soil and water, but also increase our profitability,” Mark Legvold said. Brad Jordahl Redlin , manager of the Agricultural Conservation Services department for the Minnesota Department of Agriculture, said that what farmers are doing in the state is working to reduce nutrient contamination, and he believes more farmers would like to get on board.
A soil health assistance program in the state is unique in the nation and is one that has five times the number of applicants beyond what the state funds. Despite tumult at a national level, he believes the federal government will help fund programs like this, because the programs have proven themselves effective in mitigating risks specific to every farm. “That’s the kind of model that certainly the Department of Agriculture recognizes going forward is a way to actually cut through all of the noise and all the debate and actually work with growers to optimize their performance,” Jordahl Redlin said.
ADVERTISEMENT Other speakers included Tony Runkel, lead geologist for the Minnesota Geological Survey, who shared how nitrogen in deep springs may take several decades to reappear. He described how difficult it is to see improvements in these deep aquifers even as management on the surface is improved. Dave Wall, a hydrologist with the Minnesota Pollution Control Agency, showed how improvements are being seen in many surface waters in the state, but as a whole, the state is far from its goal of a 45% nutrient reduction by 2040.
That strategy was put in place in 2014. There will be a revised strategy published this summer for public review, Wall said..
