What Plans are Important for Protecting Water Quality?
Author: Rick Koelsch, University of Nebraska - Lincoln
Before deciding on a location for a new animal feeding operation, three questions are suggested to protect water quality:
- Can I access sufficient land?
- Can I store manure safely?
- Can I safely dispose of mortality?
Can I access sufficient land?
Nitrogen (N), phosphorus (P), and carbon excreted by livestock and poultry can be valuable nutrient sources in a crop fertility program or they can be critical pollutants to our surface and ground water. The first step to assuring that N and P are utilized by the crop and don’t become water pollutants is to ensure that sufficient land base is available for crop production to utilize the N and P.
As a quick rule of thumb, use the following table to make a rough estimate of the land required for an animal feeding operation:
|Animals||Land for N*||Land for P*|
|1,000 dairy cows||1,300 ac||2,100 ac|
|1,000 beef cattle||100 ac||270 ac (open lot)|
|130 ac||270 ac (barn)|
|1,000 finishing pigs||110 ac||160 ac|
|100,000 laying hens||530 ac||1,400 ac|
|100,000 broilers||60 ac||810 ac|
*Assumes manure will be used on corn averaging 200 bushel/ac corn.
Can I store manure safely?
Storage of slurries, liquids, and long-term stockpiled solid manure can leach liquids with nitrogen and salts that may move through the soil profile toward groundwater. Careful site evaluation is needed to determine if permanent manure storage sites can be designed to minimize this risk. Depending on local soils, an earthen storage with a properly compacted soil liner may be possible. However, some sites will require a synthetic flexible liner or concrete liner for storing manure safely.
A first review of a proposed site can be done using USDA’s Web Soil Survey. A location can be
identified using the Survey’s GIS mapping tool, a selected area of interest can be identified to determine soil characteristics, and a “Suitabilities and Limitations for Use” resource for sewage lagoons can provide a preliminary idea of the appropriateness of a site. Because this tool only looks at the top soil layers, an engineering analysis will eventually be needed for a more complete review of the site.
It is also important to review a proposed site’s connections to surface water. Topographic maps showing intermittent, perennial streams, and wetlands are important to review. Nebraska flood plains and registered water wells maps, maintained by the Nebraska Department of Natural Resources, are excellent resources for understanding a potential site’s water quality risk.
Can I safely dispose of mortalities?
Prospective mortality storage, composting and burial sites should all be reviewed for potential connections to surface water with Topographic Maps and for possible location within a Nebraska flood plain. The same maps used for evaluating prospective manure storage sites will work for mortality handling sites. Sites connected to surface waters or located in flood plains should be eliminated from consideration.
If mortalities are to be buried, review local sites soils with USDA’s Web Soil Survey following the same procedure for a preliminary review as for manure storage. Burial sites with highly permeable soils or shallow water tables should be dropped from consideration.