Proper storage of used poultry litter is often overlooked as a component of litter management. Yet storage of litter plays a role in retention of valuable nutrients and the prevention of environmental pollution.
U.S. broiler growers produce nearly 9 billion birds each year for domestic and international consumption. Once the birds are sold, what is left behind is more than 11 million tons of used poultry litter. Proper storage of litter will help retain nutrients for use in crop production and minimize nutrient loss to the environment.
Why storage is necessary
The cleanout of a poultry house depends on the schedule of flocks, the bedding strategy of the farm, and often the time of year. House cleanout schedules do not always coincide with crop production periods or proper soil conditions that would allow spreading of poultry litter. Storing poultry litter properly will assure the most beneficial use of the valuable fertilizer nutrients and prevent water contamination on poultry farms.
The maximum value of poultry litter as a fertilizer occurs at the time of its removal from the poultry house. This is the point at which the nitrogen content is greatest (see Table 1). Litter that is stored or composted will lose nitrogen in the form of ammonia as it volatilizes from microbial activity within the stockpile. Uncovered litter that is exposed to wet weather conditions can generate leachate runoff that can potentially reach surface and groundwater sources. From a regulatory standpoint, such improper manure storage can be considered a point source pollution problem, exposing the farm to the possibility of permitting and assessed fines. Storing poultry litter properly, however, can reduce the amount of nitrogen lost to the atmosphere and protect the environment.
Appropriate methods for storing poultry litter
Poultry litter storage can be done in a variety of ways with a great range of investment costs and management programs.
Covered stockpiles. Stockpiles of litter can be protected from rain and erosion by covering them with plastic sheeting anchored with earth and/or other devices such as auto tires. This method is the least expensive for storing litter, but it may not be the most effective in protecting the environment. For this reason, it is recommended only as a temporary storage method. When using this method, choose an elevated, well-drained location away from drainage ditches and other water courses. Use berms or diversion ditches, if necessary, to prevent surface water from running into or through the stockpile. Anchor the edges by laying the sheeting across a small trench approximately 12 inches deep and back-filling with soil. Lay used tires or other anchoring devices over the top of the plastic. Improperly anchored plastic will become loosened in the wind and may tear or blow off the pile. Heavy gauge (6 mil) plastic sheeting works best and can last one or two seasons. Lighter gauge material is not recommended.
Stockpiles with ground liners. When stockpiles must be located on soils with a high water table, use a ground liner to prevent leaching. A liner can be as simple as a sheet of 6 mil plastic laid on the soil surface on top of which the stockpile is formed, or it can be as elaborate as a concrete slab that can be covered with plastic or a permanent cover. Ground liners prevent nutrients from leaching into groundwater. A liner must be accompanied by a cover for proper storage of the litter.
Permanent storage structures. For larger poultry operations, permanent storage structures may be the most practical method for storing litter. Permanent structures ideally will have a concrete floor and a trussed roof to prevent water infusion into the litter. The roof should be clear-span supported by outside walls or perimeter posts. Interior posts will obstruct loading and unloading and might be a source of fire if spontaneous combustion occurs within the pile. Roof heights must be sufficient to allow manure piling and equipment operation. Roofs of 12 feet or more may require wall panels to protect the stored litter from blowing rain. The Natural Resource Conservation Service (NRCS), and the Cooperative Extension Service at many universities have plans available for litter storage structures and compost facilities. It is important that a storage facility be functional and protect the litter material from storm rain and groundwater infusion.
Preventing spontaneous fires in litter storage structures
Care must be taken to operate litter storage and compost sheds in a manner that will prevent fires. Improperly stockpiled litter can generate enough heat to spontaneously catch fire within itself or near wood within the storage structure. The following steps will help prevent over-heated litter and stockpile fires:
Stored litter should not exceed seven feet in depth at the center of the pile. Excessive depth can promote higher temperatures and spontaneous combustion.
Keep different aged litter stored separately. Green or fresh litter should not be stacked on or next to older, drier litter. The variation in moisture content between the two litters is the primary cause of elevated internal temperatures. The interface where the two litters meet can become a point of ignition.
Prevent storm water intrusion. The infusion of storm water into a pile of litter can create moisture variations in the stockpile, promoting the creation of higher temperatures sufficient to ignite the stockpile.
Monitor the internal temperature of the pile using a probe-style thermometer or other appropriate temperature monitoring device. Litter with temperatures that exceed 180 degrees F must be moved immediately to prevent spontaneous combustion.
The use of poultry litter storage structures is considered a Best Management Practice for protecting the environment and maximizing the fertilizer value of poultry litter. Litter storage structures will become more important and prevalent as the poultry industry continues to implement environmentally sound litter management programs. The Cooperative Extension Service and Natural Resource Conservation Service can provide assistance in planning for and financing proper poultry litter storage facilities.
|Table 1. Average Nutrient Value Of Broiler Litters (lb/ton)|
|Broiler Litter - Fresh||63||55||47|
|Broiler Litter - Stored||56||57||46|
|Broiler Litter - Composted||56||60||46|
Source: The University of Georgia Agricultural and Environmental Service Laboratory.