Using livestock manure at appropriate rates on crop fields offers many advantages to the user, the soil and society. It makes all the sense in the world. Abusive overapplication of manure, or applying it at the wrong time, poses significant environmental and economic risk. That may especially be true for poultry litter.
“Poultry litter is a good source of forage crop nutrients only when there is a major deficiency and it’s not needed in large quantities,” says Rocky Lemus, Mississippi State extension forage specialist. “If not applied in conjunction with a soil and poultry litter analysis, nutrient imbalances can develop in a hurry. If this occurs, environmental issues such as phosphorus runoff become a concern.”
In a recent of edition of Lemus’ newsletter, Forage News, the specialist outlined a number of items producers should consider before applying poultry litter to forage fields. In Mississippi, poultry is the number one agricultural commodity with 730 million broilers produced. That makes for a lot of poultry litter to be utilized.
“Poultry litter can provide valuable nutrients for crop growth and to amend soil deficiencies,” notes Lemus. “It can also serve as a soil amendment by adding organic matter, which helps improve soil and nutrient retention. The organic matter benefit will vary with soil type, rainfall, temperature, drainage and microbial activity.”
Poultry litter, depending on the source and how it was stored, varies greatly in nutrient content. Lemus cites analysis studies where the pounds of phosphorus (P2O5) per ton as ranged from 17 in fresh litter to 80 in stockpiled litter. There were also major differences between breeder and broiler house litter. Providing additional variability is the bedding material that was used, bird type, housing conditions and the animal’s diet. The only way to deal with the ranges in nutrient value experienced with poultry litter is to have a manure analysis in hand.
As with phosphorus, nitrogen can be equally as variable. Poultry litter contains a relatively high amount of nitrogen as ammonium, which is subject to volatilization as it is exposed to the atmosphere and rainfall. Poultry litter provides, at best, equal amounts of nitrogen and phosphorus; at worst, there can be three to four times more phosphorus. Forage grasses generally require three to four times more nitrogen than phosphorus.
“Unless you have a soil phosphorus deficiency, the routine use of poultry litter based on nitrogen needs is going to result in significant overapplications of phosphorus. This may lead to an environmental risk where field water runoff finds its way to surface water,” notes Lemus.
Before deciding to apply poultry litter, Lemus encourages producers to compare costs against the commercial fertilizer alternative. There are times when poultry litter because of trucking distance or other factors may be the more expensive alternative.
Properly managed, poultry litter can be a valuable nutrient resource and an environmentally sound means to utilize what otherwise would be a waste product. Close attention to application rates based on manure and soil analysis is essential. Check with your local county extension office for specific management guidelines and the availability of poultry litter in your area.