Draft Vulnerable Groundwater Area Map
The application of nitrogen fertilizer in the fall or on frozen soils will be restricted to quarter-sections of land where 50% or more of the quarter-section is in an area with vulnerable groundwater and in DWSMAs that have nitrate concentrations in excess of 5.4 mg/L nitrate-nitrogen. An area with vulnerable groundwater is an area where nitrate can move easily through soil and into groundwater, contaminating drinking water sources. Vulnerable areas for Part 1 of the rule are defined as:
There are several exceptions to Part 1 of the rule. Fall application of nitrogen fertilizer will be allowed:
There are additional exceptions related to the presence of clay soils with ultra-low permeability, reduced leaching potential combined with a short spring planting season, and in counties with less than 3% of the land in row crops.
Ammoniated polyphosphate (MAP and DAP) and micronutrient formulations containing nitrogen can be applied as long as the applied rate does not exceed 40 pounds of nitrogen per acre. Fields with low or very low phosphorus 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 will not take effect until January 1, 2020.
Fertilizer Technical Unit Supervisor
Pesticide & Fertilizer Management Division