Casey W. Ritz, professor and extension poultry scientist at the University of Georgia, says poultry litter is a complete fertilizer that contains not just primary nutrients but secondary and micronutrients, too. Typical analysis is about 3 to 2 to 2 (N to P2O5 to K2O).
“Actual nutrient content depends on the type of bird, what birds are fed and how often the poultry producer cleans the house,” Ritz says. “Feed efficiency and how manure is handled and stored also affect nutrient content.”
Poultry litter is a beneficial organic fertilizer in Georgia, where heavy clay soils in the north and sandy soils in the south benefit from improved soil quality.
“Many south Georgia cotton growers can’t get enough poultry litter,” Ritz says. “It’s a very good resource for fertilizer and soil amendment.”
About 89 percent of poultry litter nitrogen is in an organic form, which means soil micro-organisms must convert it to ammonium or nitrate. Timing of the biological conversion depends on soil moisture and temperature.
In moist, warm conditions (above 50ºF), the largest nitrogen release is likely to happen. In cold, dry conditions, little or no nitrogen is released. For pastures and hayfields, slow nitrogen release can make nitrogen available more evenly over the growing season.
Some poultry litter nitrogen is lost to the atmosphere through volatilization, which is maximized by hot, dry and windy conditions. Applying poultry litter just prior to rainfall can help incorporate ammonium into soil through water infiltration. High rainfall may cause substantial poultry litter nutrient loss through surface runoff. Leaching can move nitrate below the root zone.
Due to these processes, only about 50 percent of poultry litter nitrogen per ton is available to plants during the growing season. Since most of the nitrogen not taken up by forages is either lost to the environment or stabilized as soil organic matter, very little carryover can be expected the second year after application.
Poultry litter’s slow release and conversion can be an advantage to farmers unless an immediate nitrogen flush is needed. For growers in Georgia, poultry litter also helps maintain soil pH, which means farmers who need lime to improve soil pH are likely to see extended liming benefits.
Roper raises about 114,800 broilers each year. Verner contracts with a poultry company annually to raise some 50,000 egg-laying hens.
Across the state, Georgia’s poultry industry produces some 1.3 billion broilers, 12 million commercial laying hens, 11.8 million broiler breeder hens and 12 million replacement pullets each year. Litter produced by the industry is valued at more than $60 million per year.Roper and Verner use litter from their own poultry facilities, noting that the manure’s organic matter is one main benefit of the practice.
“Farmers in our state sometimes haul chicken litter as much as 200 miles to apply it to row crops,” Verner says. “That’s how important the litter’s organic matter is to soil quality.”
On his northeast Georgia farm, Roper raises broilers, beef cattle, some corn, alfalfa and hay. Bermudagrass and fescue are predominant in his hayfields. He harvests an average of 4 to 6 tons of bermudagrass and fescue per acre.
For the past 15 years, Roper’s broilers have been housed in four different facilities bedded with sawdust on dirt floors. Each flock walks on 3 to 4 inches of sawdust. Each time a flock finishes, hard manure “cake” is removed, and a thin layer of shavings is added to the composting bed.
Typically, Roper sells broilers in October, clears all the litter from the buildings and immediately applies it to his fields. Using a standard manure spreader, Roper distributes between 4 and 5 tons of litter per acre. Rather than test his litter every year, he relies on soil samples to indicate the need for adding any commercial nutrients.
“The more flocks producing litter, the more nutrient value it’s likely to have,” Roper says. “If someone has litter from just one or two flocks of broilers, I wouldn’t be interested in it because it probably contains a high percentage of sawdust. I have had litter from five or six flocks with very balanced nitrogen, phosphorus and potassium.”
After raising six to seven flocks in his poultry facility (108,000 to 114,000 per flock), Roper’s litter analysis runs 50 to 60 pounds on NPK per ton. If the house is cleaned after one or two flocks, litter nutrient levels are lower.
When the same type of birds are fed the same feed ration for the same period of time, and poultry houses are cleaned out at the same rate each year, poultry litter analysis is likely to remain fairly constant.
Poultry houses that sell litter are required by law to provide a nutrient analysis. For private growers like Roper and Verner, analysis of litter for their own use isn’t always feasible. Samples can be taken prior to distribution; however, poultry litter quickly loses nutrients when exposed to the elements and is typically removed from the poultry house and immediately applied.
For growers producing high-quality hay, feathers within the litter that don’t break down could cause buyers to reject hay, making poultry litter an unacceptable fertilizer resource.
In Verner’s facility east of Atlanta, he raises beef cattle, operating an embryo transfer program using predominantly purebred Angus. His crops include hay and baleage produced from both ryegrass and bermudagrass. Per cutting, he harvests an average of 2.5 tons of rye baleage (60 percent moisture) and about 2 tons of bermudagrass per acre.
Verner’s hens produce and hatch fertilized eggs in a facility with a suspended floor so chickens walk on slats and manure drops down below them. The flock is all-in, all-out once each year.
“Once the hens go out, we hire a crew, move the slats and remove all manure using skid loaders,” Verner says. “With a 20-foot spreader, we immediately apply about 10 tons per load on approximately 1,000 acres that are all within a mile or less of the poultry house."
"Our ryegrass is usually planted between four and six weeks before we apply the litter. That all depends on weather conditions for planting and manure application.”
At the same time he applies litter, Verner utilizes an Aerway aerator to incorporate it into the soil. The aerator allows him to set aerator tines to either barely or more aggressively puncture the top 6 inches of soil.
“The aerator is a great tool to open up paths for the manure to reach plant roots quickly,” Verner says. “We have used it aggressively in areas where compaction from equipment or cattle were a concern.”
From time to time, both Verner and Roper have struggled with getting manure applied between rains and wet field conditions. Neither of them stockpile the manure outside poultry facilities due to litter’s volatile nature.
“We observe all the same manure distribution regulations as other livestock owners,” Roper says. “There’s so much grassland in our area that nutrient runoff isn’t really an issue, but we don’t apply litter in wet weather conditions.”
If he spreads litter on a pasture, Roper prefers to keep his beef cattle out of it until after a rain. However, conditions sometimes require that cattle return to the pasture immediately following distribution. He hasn’t seen any negative impact from the practice.
Because grasses normally require three or four times more nitrogen than phosphorus, use of litter – with almost equal amounts of both – can result in phosphorus buildup. That happens more slowly on fields where hay is removed.
Since Roper and Verner usually produce their own litter each year, it’s a relatively low-cost fertilizer source. However, both hire crews to help clean facilities and spread the nutrients, so the litter isn’t free. Verner believes the litter’s organic matter is especially valuable in helping rebuild soils, which some in his area refer to as “cottoned to death.”
“In the 1930s through the ’50s, farmers didn’t have access to all the best management practices we know about today,” Verner says. “They didn’t have no-till or information about protecting soil quality."
"All they had was terracing, which wasn’t much help to keep soil from washing away over the years. Poultry litter is one of the products farmers here use to help rebuild organic matter and restore topsoil.”
Ritz points out that a flush of weeds may take hold in a field following the first few applications of poultry litter. The reason for vigorous weed growth is the favorable growing conditions poultry litter provides.
“Since poultry litter is a complete fertilizer, it provides a balanced environment for all plants, including weeds,” Ritz says. “If weed seeds lie dormant in the soil, applying litter could stimulate weed growth.”
While neither Verner nor Roper has experienced problems with high-nitrogen poultry litter that burned crops, there is potential for it to happen when the actual analysis of litter is unknown.
If fast-growing crops take up excess nitrates from grasses fertilized with poultry litter, livestock could become ill or die as a result. Verner recommends that producers interested in using poultry litter start small.
“Learn as much as you can about poultry litter and see how it works for your crops before large-scale use,” Verner says. “Georgia row-crop producers use it quite heavily, and it’s readily available here." Once it’s applied, they disk it in as soon as possible to avoid losing nitrogen and other nutrients to the atmosphere or leaching.
“My main recommendation is not to overdo use of the litter when you’re starting,” Verner says. “Start with a small area and observe results before expanding. It definitely can help cut costs and build organic matter.” FG
Loretta Sorensen is a freelancer based in South Dakota.
PHOTO: Verner uses poultry litter to fertilize the rye and bermudagrass crops he raises for forage. Photo provided by Alan Verner.