IMMAG - Iowa Manure Management Action Group

Kris Kohl, Iowa State University Extension agricultural engineering field specialist, compiled this summary document of the most up-to-date information on Senate File 432. As SF 432 has not been finalized yet, the ruling outlined below is still subject to change.

Winter manure application and stockpiling regulations
Senate File 432 made changes that will affect some beef producers in how they handle manure applications in the winter and how they stockpile their manure. The bill was signed into law however, due to the regulatory process in Iowa, the DNR will be required to adopt rules to implement this law. Producers should be advised the law is effective even if the rules to enforce the law have not been finalized. The law addresses winter manure application, stockpiling dry bedded manure, and constructing bedded barns and bedded manure storage structures.

Winter manure application
Between December 21 and April 1 surface application of liquid manure is prohibited on snow-covered ground except in the event of an emergency.

Between February 1 and April 1 surface application of liquid manure is prohibited on frozen ground except in the event of an emergency.

Emergencies are defined as “unforeseen circumstances beyond the control of the owner” such as natural disasters, weather related events, or equipment or structural failure. When an emergency happens the producer must:

1) notify the DNR by telephone;
2) apply the liquid manure to a field identified in the manure management plan for emergency application; report the application in next updated plan;
3) apply manure to field with a Phosphorus Index of 2 or less;
4) block surface water intakes from the time of application until 2 weeks after the completion of the application.

This law only applies to liquid manure from confinement feeding operations and does not apply to solid manure or liquid manure from an open feedlot unless the terms of the permit for the open feedlot state that no application is allowed under these conditions. Standard separation distances must be observed for all surface applied manure to water sources.

Stockpiling Dry Bedded Manure from Confinements

Dry bedded manure from cattle and hog confinements is allowed to be stockpiled outside of the confinement structure if the following requirements are met:

1) the stockpile is 1,250 feet or more from a residence, church, school, or public use area including cemetery, unless you receive a written waiver; small animal feeding operations are exempt from this requirement;
2) the stockpile is 200 feet from surface tile inlet, unless steps are taken to ensure runoff will not reach the tile inlet;
3) the stockpile is 400 feet from a designated area or 800 feet from a high quality water resource;
4) the stockpile is not located in a in grass waterway; where water pools or where surface water will enter the stockpile;
5) the stockpile is on 3% slope or less, unless measures to contain runoff are implemented;
6) in Karst terrain or over alluvial or sand or gravel aquifers there must be at least 5 feet of separation distance between the bottom of the stockpile and the limestone, soluble rock or sand and gravel aquifer, and the stockpile must be placed on 5inches of reinforced concrete; and
7) the stockpile must be removed and land applied within 6 months.

It should be noted that stockpiling dry poultry manure is subject to different rules and any livestock operation with a NPDES permit must follow all provisions of the permit.

Construction Requirements for Dry Bedded Confinement Feeding Operations
The law requires construction requirements for the following when building a new dry bedded barn or bedded barn manure storage structure.

500 feet or more from a surface intake to an ag drainage well;
1,000 feet or more from a wellhead, cistern of an ag drainage well, or known sinkhole;
200 feet or more from a water source
1,000, feet or more from a major water source
2,500 feet from a designated wetland
shall not be constructed on a 100 year flood plain

Provisions to prevent moving water sources closer to the bedding barn or manure storage structure.
Structures built on karst topography or alluvial aquifers must maintain at least 5 feet between the bottom of floor of the structure and the underlying limestone or alluvial aquifer and the dry bedded confinement structure must be built on reinforced concrete that is at least 5 inches thick.
In addition to the above requirements, the definition of adjacency, common ownership and common management are defined for purposes of determining if multiple dry bedded confinements are one feeding operation. Producers should consult the DNR before constructing a dry bedded confinement.

For more information visit:
For a list of definitions of water sources as used in this article please consult the following resources:
DNR 117, High Quality Water Resources,
Major Water Sources- Rivers and Streams
Major Water Sources- Lakes