The MDA held informal and formal comment periods, 17 listening sessions across the state and received more than 800 written comments. The Groundwater Protection Rule became law in June, 2019. Application restrictions are posted on the MDA’s website by January 15 each year and the fall application restrictions begin September 1. See question 11 below for more detail on the fall and frozen soil restrictions.
There are two parts to the rule. Each part contains separate provisions. Depending on where you farm, you may be subject to one part of the rule, both parts, or neither part.
Part 1: You are subject to Part 1 of the rule if you farm in a vulnerable groundwater area or in a Drinking Water Supply Management Area (DWSMA) that has 5.4 mg/L or higher of nitrate. This means you cannot apply nitrogen fertilizer in the fall and on frozen soils in those areas.
Part 2: You are subject to Part 2 of the rule if you farm land in a DWSMA with elevated groundwater nitrate concentrations. These areas will be designated a mitigation level 1, 2, 3 or 4.
There are two parts to the rule. Each part contains separate provisions. Depending on where you farm, you may be subject to one part of the rule, both parts, or neither part.
Part 1: You are subject to Part 1 of the rule if you farm in a vulnerable groundwater area or in a Drinking Water Supply Management Area (DWSMA) that has 5.4 mg/L or higher of nitrate. This means you cannot apply nitrogen fertilizer in the fall and on frozen soils in those areas.
Part 2: You are subject to Part 2 of the rule if you farm land in a DWSMA with elevated groundwater nitrate concentrations. These areas will be designated a mitigation level 1, 2, 3 or 4.
A vulnerable groundwater area is land where nitrate can move easily through soil and into groundwater. The criteria used to determine vulnerability include coarse textured soils, karst geology, or shallow bedrock. The USDA NRCS soils maps were used to determine coarse textured soils and shallow bedrock. Coarse textured soils are within 91 cm of the soil surface and soils with shallow bedrock in the soil profile are within 102 cm of the soil surface.
A Minnesota Department of Natural Resources Pollution Sensitivity of Near-Surface Materials Report was used to identify the locations of karst.
A vulnerable groundwater area is land where nitrate can move easily through soil and into groundwater. The criteria used to determine vulnerability include coarse textured soils, karst geology, or shallow bedrock. The USDA NRCS soils maps were used to determine coarse textured soils and shallow bedrock. Coarse textured soils are within 91 cm of the soil surface and soils with shallow bedrock in the soil profile are within 102 cm of the soil surface.
A Minnesota Department of Natural Resources Pollution Sensitivity of Near-Surface Materials Report was used to identify the locations of karst.
The application of nitrogen fertilizer in the fall and on frozen soils will be restricted in areas with vulnerable groundwater or DWSMAs that are at or exceed 5.4 mg/L nitrate-nitrogen. An area with vulnerable groundwater is an area where nitrate can move easily through soil and into groundwater.
The criteria used to determine vulnerability include coarse textured soils, karst geology, or shallow bedrock. View the interactive Vulnerable Groundwater Area Map to see where application of nitrogen fertilizer will be restricted. Vulnerable quarter sections are shown in purple and DWSMAs are in green on the map.
In areas where 50% or more of the quarter section has vulnerable groundwater or is in a DWSMA, with high nitrate, applications of nitrogen in the fall and on frozen soils will not be allowed in the entire quarter section. If less than 50% of the quarter section has vulnerable groundwater, the restrictions do not apply.
The application of nitrogen fertilizer in the fall and on frozen soils will be restricted in areas with vulnerable groundwater or DWSMAs that are at or exceed 5.4 mg/L nitrate-nitrogen. An area with vulnerable groundwater is an area where nitrate can move easily through soil and into groundwater.
The criteria used to determine vulnerability include coarse textured soils, karst geology, or shallow bedrock. View the interactive Vulnerable Groundwater Area Map to see where application of nitrogen fertilizer will be restricted. Vulnerable quarter sections are shown in purple and DWSMAs are in green on the map.
In areas where 50% or more of the quarter section has vulnerable groundwater or is in a DWSMA, with high nitrate, applications of nitrogen in the fall and on frozen soils will not be allowed in the entire quarter section. If less than 50% of the quarter section has vulnerable groundwater, the restrictions do not apply.
Yes, fall application of nitrogen fertilizer will be allowed in vulnerable groundwater areas or DWSMAs with high nitrate concentrations in wells, in the following situations*:
- to establish winter grains planted in the fall;
- for fall pasture fertilization;
- for perennial crops;
- for grass seed production;
- for cultivated wild rice;
- for research on fields 20 acres or less in size, or
- for growing fall cover crops within a potato rotation
*Must follow University of Minnesota nitrogen rate guidelines for each of the above.
There are additional exceptions and exemptions related to: soils with ultra-low permeability referenced in the rule; in areas with reduced leaching potential combined with a short spring planting season; and in counties where cropland makes up less than 3% of the total land area.
Ammoniated polyphosphate (MAP and DAP) and micronutrient formulations containing nitrogen can be applied as long as the applied rate does not exceed an average of 40 pounds of nitrogen per acre in a field. Fields with low or very low phosphorus levels, as determined by a certified lab, are exempt from this restriction.
Fall nitrogen fertilizer applications will also be allowed for agricultural research and demonstrations for academic purposes, provided the area is limited to 20 acres or less, or approved by the Commissioner of Agriculture.
These restrictions begin September 1, 2020.
Yes, fall application of nitrogen fertilizer will be allowed in vulnerable groundwater areas or DWSMAs with high nitrate concentrations in wells, in the following situations*:
- to establish winter grains planted in the fall;
- for fall pasture fertilization;
- for perennial crops;
- for grass seed production;
- for cultivated wild rice;
- for research on fields 20 acres or less in size, or
- for growing fall cover crops within a potato rotation
*Must follow University of Minnesota nitrogen rate guidelines for each of the above.
There are additional exceptions and exemptions related to: soils with ultra-low permeability referenced in the rule; in areas with reduced leaching potential combined with a short spring planting season; and in counties where cropland makes up less than 3% of the total land area.
Ammoniated polyphosphate (MAP and DAP) and micronutrient formulations containing nitrogen can be applied as long as the applied rate does not exceed an average of 40 pounds of nitrogen per acre in a field. Fields with low or very low phosphorus levels, as determined by a certified lab, are exempt from this restriction.
Fall nitrogen fertilizer applications will also be allowed for agricultural research and demonstrations for academic purposes, provided the area is limited to 20 acres or less, or approved by the Commissioner of Agriculture.
These restrictions begin September 1, 2020.
Mitigation is the action of reducing the severity of a problem. In addressing the problem of nitrate contamination, mitigation levels will be based on nitrate data collected from public wells.
