The text below outlines the language from the first draft of the Groundwater Protection (Nitrogen Fertilizer) Rule. Please view the Draft Groundwater Protection Rule for the current draft.
The application of nitrogen fertilizer in the fall or on frozen soils will be restricted in areas with vulnerable groundwater. An area with vulnerable groundwater is an area where nitrate can move easily through soil and into groundwater. The criteria used to determine vulnerability includes the saturated hydraulic conductivity of a soil (Ksat≥ 10 micrometers/second, roughly 1.4 inches/hour), near-surface bedrock and karst geology. Ksat is a physical property of the soil and is widely used by soil scientists to describe the soil's capacity to transmit water. Because Part 1 of the Rule is based on soils and geology, the area covered by the Rule is not subject to change over time. A field in a vulnerable groundwater area will always be subject to Part 1 of the Rule.
In areas where more than 50% of the section has vulnerable groundwater, fall and frozen soil application will not be allowed in the entire section.
If less than 50% of the section has vulnerable groundwater, fall and frozen soil application is restricted on fields with karst or near surface bedrock or where the predominant soil type is vulnerable.
Fall application of nitrogen fertilizer will be allowed in vulnerable groundwater areas to:
If the Rule is adopted as this draft, all areas identified with nitrate contaminated groundwater will begin in a voluntary level of mitigation. A local advisory team will advise the Minnesota Department of Agriculture regarding appropriate response activities for the area and to support implementation of these activities. Use of nitrogen fertilizer best management practices (BMPs) and alternative practices are key components of Part 2 of the Rule.
The Rule outlines a multi-level approach designed to involve local farmers and agronomists in helping to reduce nitrate losses in areas with high nitrate in groundwater. There are four mitigation levels. Mitigation is the action of reducing the severity of a problem. The initial designation of a mitigation level is based on nitrate concentrations that are near to or exceed the nitrate health risk limit of 10 milligrams per liter. Nitrate data from public and private wells will be used to prioritize areas of greatest concern and to determine if mitigation is necessary. Because Part 2 of the Rule is based on nitrate concentrations in drinking water, the area covered by the Rule is subject to change over time. An area may move in and out of the mitigation levels. All areas identified with elevated nitrate contamination will begin in a voluntary mitigation level 1 or 2.
View a map of nitrate data from private wells to see which townships are subject to Part 2 of the Rule.
The area covered by the designation will be defined using township boundaries (for household/private wells) or drinking water supply management area boundaries (for community/public wells). A drinking water supply management area (DWSMA) is the area from which water will reach a public water supply well within approximately 10 years. DWSMA boundaries are defined by the Minnesota Department of Health.
A local advisory team, consisting primarily of producers and Ag professionals will advise the MDA regarding appropriate response activities for the area and to support implementation of these activities. Recommended nitrogen fertilizer Best Management Practices (BMPs) and alternative practices will be promoted within these vulnerable areas. After three growing seasons, the MDA will reevaluate the mitigation level. If nitrogen fertilizer BMPs are being used on 80% of cropland in the designated area (township or DWSMA), regulations will not be required. If nitrogen fertilizer BMPs are not being used, the area can move into a regulatory level. The Rule will include a list of site specific management practices that may be required in areas that progress to regulatory mitigation levels 3 and 4. The mitigation criteria is shown in the diagram below.