Manure Management for Water Quality

WHY SHOULD i BE CONCERNED?

Animal manure can be a valuable nutrient source and soil conditioner. When managed properly, the nutrients in manure can be substituted for commercial fertilizers, saving money and protecting both ground water and surface water. Matching nutrient applications to crop nutrient needs is critical.

LONG-TERM MANURE STORAGE

Runoff from improperly stored or managed manure can lead to contamination of groundwater and surface water. Land application of manure at proper agronomic rates or composting of manure conserves nutrients contained in the manure and minimizes leaching and runoff of contaminants. Manure storage in an appropriate structure increases a producer's flexibility regarding the timing of land applications. Storage is also valuable during extended periods of bad weather and when crops are actively growing, making application impractical.

Proper management of stored manure depends on proper design and construction of the storage facility, a good knowledge of the physical and chemical characteristics of the soil and subsurface geologic materials within the storage area, and proper land application of manure once it leaves the storage facility.

LONG-TERM STORAGE OPTIONS

Livestock manure can be stored for more than 90 days either in solid, semi-solid (slurry) or liquid states. Solid facilities use walls and slabs for piling heavily bedded or frozen manure.
Slurry facilities use pumps to move manure into storage areas where some solids may be separated from liquids.
Liquid facilities hold manure in tanks, pits, earthen lagoons, evaporation ponds or bermed areas.

PROBLEMS WITH LEAKAGE

Liquid and semi-solid storage systems, in particular, must be carefully installed and maintained to ensure that they do not leak. Lagoons need to be big enough and lined with earthen or other materials to provide a very low liner hydraulic conductivity of no less than 1 x 10-7cm/sec. Freezing, thawing, wetting and drying cycles, and even earthworm or other animal burrows may cause leaking through a liner. The effective life for properly designed lined earthen pits is approximately 10 years.

> > TAKE ACTION!
CHECK FOR LEAKS

Check for leaks and repair structures whenever structures or pits are emptied:

In lined systems: check walls and bottoms for cracks in watertight seals.
In earthen pits: check for erosion of liner materials.

Look for the following as a sign of leakage. If a pit has been receiving designated liquid manure amounts and you are adding additional milk house liquids, but the pit has not required pumping, it is probably leaking.
Monitoring wells installed around the pit upslope and downslope can confirm the seepage. Talk with your Utah State University County Extension agent or contact the Utah Division of Water Quality for more information.

SHORT-TERM MANURE STORAGE

Short term storage is not a recommended practice, because it poses a risk of contaminating surface water and ground water. However, short-term storage is sometimes necessary to hold livestock manure during periods of bad weather when daily spreading may not be feasible, when crops are growing and land is not available for applying manure or when there is a shortage of crop acres to handle daily hauling and spreading of manure without the threat of runoff. Short term storage does not replace a properly planned long-term storage facility and livestock growers should develop a plan to reduce the need for any short-term storage system for their operation.

The best ways to handle any drainage from a short term storage facility is to channel it into a lined watertight holding pond, storage tank or into a constructed filter strip. In situations where these options are not possible, it may be necessary to build a covered (and curbed) storage area to prevent additional water from being added to temporarily piled manure.

Some solid or semi-solid manure storage systems (such as picket dams) are designed to allow minor drainage of liquids. In these cases, the structure design must include containment and/or treatment of liquids that drain out.

> > TAKE ACTION!
CHECK FOR LEAKS

To minimize leakage or runoff from short-term storage sites:

Store manure in pole sheds or other roofed areas to keep rain and snow off.
Provide adequate bedding in piles to absorb liquids in the manure.
Clean these areas as frequently as possible.

LOCATING A STORAGE MANURE FACILITY

When locating a manure storage facility, there are several important factors to consider:

the depth of the water table.
type of soils and bedrock.
potential for contaminating water.

REQUIRED SEPARATION DISTANCE

Utah Law requires minimum separation distances between most storage facilities and wells. New private wells require minimum separation distance of 100 feet from storage areas. Existing wells are regulated by separation requirements in effect at the time of well construction. Make every effort, however, to exceed “old regulations” and strive to meet current separation distances when possible.

The minimum separation distance between a manure lagoon and a public well is 100 feet if the well is in a confined aquifer or an estimated 250 day pollution plume travel time. If your well is in an unconfined aquifer, contact Utah Division of Drinking Water to determine separation distances. For liquid-tight manure storage structures, no minimum separation distance is specified but as much distance as possible should be provided.

> > TAKE ACTION! REDUCE CONTAMINATION WITH PROPER LOCATION

Locate manure storage facilities:

as far away and downhill from any well or surface waters.
in a site that remains above the water table throughout the entire year
avoiding areas with fractured bedrock or areas with extremely permeable soils (such as sandy soils).

ABANDONED PITS

Abandoned manure storage pits, especially earthen ones, can pose significant water quality problems. Any abandoned structure should be completely emptied. In the case of earthen waste storage facilities, liner materials (to a depth of about two feet) should be removed and spread over croplands. The remaining hole should be filled and leveled. Manure packs from pole sheds no longer in use should also be removed and the manure applied. If manure has been piled in fields, it should be removed and applied at appropriate agronomic rates as soon as conditions permit.

MANURE APPLICATION PRACTICES

MANURE APPLICATION

Manure should be applied based on the nitrogen or phosphorus needs of the crop. A comprehensive nutrient management plan (CNMP) accounts for all nutrient inputs and outputs. For more information, contact Utah State University Extension Ag Management, Utah NRCS or Utah State University Extension Water Quality. The amount of manure produced, along with the nutrient content, should be balanced with the amount of acres needed for proper distribution. Remember that when manure is incorporated into the soil immediately after application, it will retain more of its nutrient value.

Where the cropable acreage is not adequate, manure may be distributed to other lands (i.e., rangeland, neighbors, etc.) or composted. Composted manure can be used as bedding, feed supplements, or as soil amendments.

When bare ground is adjacent to an irrigation ditch or other water source, an appropriate set back area should be maintained. Manure should not be applied in the set back area. The distance across the set back area is determined by slope, vegetative cover, type of irrigation and other factors that influence runoff. Manure should not be applied to frozen or snow covered ground unless all runoff can be controlled.

SIMPLE PRINCIPLES FOR MANURE APPLICATION

Manure application can improve soil structure and restore nutrients to the soil.
To prevent excess phosphorous or nitrates in your soils, you should account for the quantities already in your soil, in any manure or compost applied and in commercial fertilizer.
Particular care should be taken if applying manure to sites with coarse textured soils, fractured bedrock and low water holding capacity. These sites have a high potential for leaching of nutrients, particularly nitrates, and microorganisms into the ground water.

MORE INFORMATION ON MANURE APPLICATION:

USU Extension Ag Waste Management: Manure Application
USU Extension Ag Waste Management: Handling & Storage
USU Extension Ag Wast Management: How Much Manure Does Livestock Produce?