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January 16, 2024
This month we continue our discussion of nitrate and drinking water issues, with emphasis on the current situation playing out in southeast Minnesota’s karst region. Recall that in recent months, activists petitioned the U.S. Environmental Protection Agency, asking it to step in and take action where they allege state agencies have failed to act.
The primary focus of this petition is a call for new or increased levels of regulation of farmers, citing private well testing results showing that in the karst region, about 10% of wells would not meet the nitrate drinking water standard of 10 milligrams per liter.
How did we get here? This story starts more than 75 years ago, in the 1940s. According to the Minnesota Department of Health, there were nearly 150 cases of methemoglobinemia, often called blue baby syndrome, in Minnesota during the 1940s and 1950s. Tragically, 14 cases resulted in deaths.
Some of these cases occurred on farmsteads. Bear in mind that most early farms relied on hand-dug wells, often located near the barn to provide water for livestock. Manure storage was often based on ease. Livestock yards, especially in spring, could be muddy and messy from snowmelt.
This is not to disparage farmers of that time, whom I hold in high regard. Their hard work and ingenuity largely built this wonderful industry. There are simply some things we know today that they did not know.
Education about the causes and symptoms of methemoglobinemia was ramped up. County health programs began to emphasize the importance of safe water for infants.
The methemoglobinemia crisis was a wake-up call. Changes began to happen on farms. Manure storage locations were evaluated and moved. This effort was aided by machinery inventions.
New wells were drilled, in better locations and with protection from runoff. New wells were located safe distances from feedlots and septic drain fields. Feedlots were changed to prevent direct runoff toward wells. This began even before the development of modern well codes in 1974.
Other actions originating in that era include water testing and finding other sources of drinking water. This was also an era when sewage handling and treatment in cities began to advance.
Through the combined efforts of farmers and city folks, methemoglobinemia cases were almost completely eliminated. The MDH reports that in 1979 and 1980 there were two cases of methemoglobinemia reported in Minnesota. In both cases, nitrate concentrations were well over 50 mg/L, and both cases were resolved once an alternative source of water was found. There have been no reported cases in recent decades.
Specific to the karst region, farmers continue to address the underlying issues with nitrates in groundwater. Those early efforts to protect wells from runoff continue even today, yet estimates suggest there are thousands of wells, not all of them on working farms, that do not meet modern well code requirements.
Farmers in the karst region began shifting away from traditional fall nitrogen fertilizer applications several decades ago. Today, fall nitrogen fertilizer applications are prohibited.
Motivated by both economic and environmental factors, farmers in the region have been working to fine-tune nitrogen application rates. Whether from manure or fertilizer, they strive to get the most value out of these nutrients while minimizing potential impacts to groundwater. Sales and survey data show steady improvements in nitrogen use efficiency over time.
Specific to livestock farms, manure storage is improving. Still, some farmers indicate that more storage would allow them to manage manure application timing better. Cost-share funding by USDA’s Natural Resources Conservation Service has been a significant provider to this effort.
More recent efforts include cover crops or double cropping. Increasing the fraction of the growing season with active plant growth can reduce nitrate movement.
University of Minnesota Extension, with support from the Minnesota Corn Research and Promotion Council, delivers the latest in water and nitrogen science through the Nitrogen Smart program. Available statewide, this program includes fundamentals for minimizing nitrogen losses while optimizing returns to fertilizer investments.
Better understanding of how water moves in the karst region also helps. Surface water and groundwater interact in unique ways in karst landscapes. Recognizing the complexity of these interactions, the Minnesota Department of Agriculture has spearheaded an effort to study water quality and movement through the Root River Field to Stream Project since 2009. Participating farmers have installed new or restored grass waterways, and water and sediment control basins, and have made feedlot improvements with support from the MDA and NRCS.
Southeast Minnesota farmers also constitute a large portion of participants in the MDA’s Nitrogen Management Initiative. This program provides cost-share and coordinated evaluation of nitrogen rates and yields. Participants conduct comparison trials on their own fields to fine-tune nitrogen rates and other factors.
These are just a few examples of farmer contributions in response to a health crisis and environmental challenges.
Read more about:Nitrates
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