Can a farmer spread manure or fertilizer on a day the Runoff Risk Advisory Forecast map shows as high risk?

In many situations the short answer is a qualified “yes.” The Runoff Risk Advisory Forecast (RRAF) is an advisory tool that provides farmers and other professional nutrient applicators with information about the likelihood of runoff from rainfall or snowmelt occurring based on data from a National Weather Service flood forecasting model. The forecast takes into account snow accumulation and melt, soil moisture content, forecasted precipitation and temperatures to predict runoff and displays the risk of runoff using a series of colored grids, 2 km x 2 km (approx. 1.25 x 1.25 sq. mi) in size. The model currently predicts runoff from rainfall out up to 5 days in the future, and snowmelt out up to 10 days.

Today’s Runoff Risk Advisory Forecast isn’t just determined by today’s weather and soil conditions. The forecast for today is looking ahead to the next 3 days to see if runoff triggering events are going to occur. Why? Because manure applied today could easily runoff with tomorrow’s rains!

The results of the RRAF maps should be considered along with other knowledge about the condition of the fields in order to make a determination if manure or other crop nutrients should be applied.

What are the laws regarding when a farmer can or cannot spread?

All farms in the state are required to comply with Wisconsin’s agricultural standards and prohibitions, regardless of the size of the farm. These performance standards are detailed in ch. NR 151, Wis. Adm. Code ( The conservation practice standards designed to help farmers meet the performance standards are explained in ch. ATCP 50, Wis. Adm. Code ( Federal and state law also requires large animal feeding operations to have water quality protection permits. The rules governing how these permits are issued and implemented are contained in ch. NR 243, Wis. Adm. Code (

In addition to the state agricultural conservation standards, some counties like Dane and Kewaunee have adopted local ordinances controlling primarily winter applications of liquid manure. To find out if there are local ordinances in your county, contact your local land conservation department. Contact information can be found here:

Farming operations across the state require a variety of management strategies.

Agricultural operations across the state are very diverse and as a result, follow a variety of daily management strategies to meet the nutrient needs of the crops they grow and the livestock they feed and care for. Some farming operations have large storage facilities for the animal waste generated daily. These facilities can hold several months or more of manure, but eventually reach the point where they must be emptied and spread on nearby cropland to serve as fertilizer. Other farms haul manure on a daily basis. Some operations have a liquid manure to spread, others very dry. There is no “one size fits all” for farming operations when it comes to managing the manure or other nutrients being applied to feed the crops being grown.

The RRAF should be used as one factor when deciding if it is a good time to make nutrient applications.

The decision when to spread manure or apply other crop nutrients is based on a number of factors that vary from farm to farm. The RRAF and 590 nutrient application restriction maps (available through SnapMaps: ) provide information that, combined with a knowledge of field-specific conditions, allow for better decisions on the timing of nutrient applications.

Have questions about what you see happening in crop fields near your home? Who can I talk to?

Your local land conservation department is usually the first place to go to for information about farming operations in your county. In many cases they will have firsthand knowledge of common practices being used to manage manure and other crop nutrients in your area. A listing of all the land conservation departments in the state and their contact information can be found here: