The Nitrogen Fertilizer Rule (Rule) contains two parts, each containing separate criteria and requirements. How the Rule applies to a field is dependent upon the field location. The Rule may apply in one part, both parts, or not at all.
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. The map shows where the Rule may apply. Areas in brown are considered the most vulnerable to pollution.
Soils information is not yet available for portions of Lake and Pine counties.
How was this map created? Is my field in a draft Vulnerable Groundwater Area?
Use an interactive map to view individual sections. Use the Draft Vulnerable Groundwater Area boundaries to determine the areas 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.
There are a few exceptions to the restriction.
Fall application of nitrogen fertilizer will be allowed in vulnerable groundwater areas to:
Part 2: Follow nitrogen fertilizer BMPs
Draft Nitrogen Fertilizer Rule Language (PDF: 694 KB/27 pages)
Fertilizer Technical Unit Supervisor
Pesticide & Fertilizer Management Division