By Charmain Tan Courcelle

MISSISSIPPI STATE -- Research conducted at Mississippi State University will soon alter existing state nutrient management plans for Mississippi broiler producers since broiler house conditions are different than what was expected.

Nutrient levels in poultry litter correspond to nutrient levels in the food broilers eat. Traditionally, poultry litter, which is a combination of bedding material and poultry manure, has been used as a fertilizer or soil amendment. Poultry litter is a rich source of nutrients for crops, however, using too much of this material can lead to increased nitrogen and phosphorus in field runoff with significant environmental concerns. To prevent problems, nutrient management plans are designed to monitor the nitrogen and phosphorus levels in poultry litter.

Nutrient management plans previously established by the Natural Resources Conservation Service of the U.S. Department of Agriculture were based on a mathematical formula generated from data collected in other states. According to this model, after five years of production, the litter in a broiler house would contain five times the amount of nutrients and a producer would have five times the amount of litter as after one year of production.

Mississippi Agricultural and Forestry Experiment Station researchers found that this is not the case in Mississippi.

"With implementation of comprehensive nutrient management plans coming to all broiler farms, we realized that we did not have the data describing the nutrient value of Mississippi broiler litter," said Tim Chamblee, MAFES poultry scientist.

Litter nutrient values vary among states, as well as within a state, based on the type of feed and nutrients chickens receive. When starting the research, Chamblee said one of the concerns was that existing nutrient management plans might not accurately reflect the situation in Mississippi.

A second concern was that these nutrient management guidelines had the potential to overestimate the nutrient value and amount of poultry litter produced in Mississippi, and thus, severely restrict use of litter as fertilizer on pastureland.

"We set out to look at what happens to nutrients over time as litter ages and to determine the amount of litter produced in Mississippi," Chamblee said.

For nearly six years, Chamblee and graduate research assistant Ricky Todd collected litter from 197 Mississippi broiler houses and analyzed the samples for the amounts of nitrogen, phosphate and potash (N-P-K) present.

"We found that while tonnage of litter increased over time, it did not increase as quickly as previously predicted," Chamblee said. "We also found, on a pound per ton basis, that N-P-K levels increased greatly from the first flock to the fifth flock, or first year of production, but remained constant after the fifth flock out to 28 flocks of production.

"The bottom line is we don't have as much litter nor are the levels of nutrients in the litter as high as was once thought. Part of this result is because of natural decomposition and microbiological breakdown that occurs in the litter while it is in the chicken house."

Chamblee began his studies with broilers because of the magnitude of broiler production in Mississippi, however, he plans to extend his work to provide producers with information on breeder and pullet litter.

Because of Chamblee's research, Mississippi will be able to revise nutrient management plans for broiler producers, allowing them to utilize more of their litter while preserving the environment.

"Tim Chamblee's work will allow us to do a better job of planning the requirements for land application of poultry byproducts," said Larry Oldham, MSU Extension nutrient management specialist in Plant and Soil Sciences. "His research showing that the quantity of litter is less than we originally thought lessens our concerns of over-supply of poultry byproduct in south central Mississippi."