Poultry manure boosts yields, protects water.
A six-year study was initiated to determine the impact of poultry manure applications on nutrient uptake by crops and on surface and groundwater quality. Three nitrogen treatments are being investigated--both 168 and 336 kg per ha (150 and 300 lb per acre) of nitrogen from poultry manure, and 168 and 336 kg per ha (150 and 300 lb per acre) from a commercial fertilizer of urea-ammonium nitrate.
The research involves nine, 0.41-ha (1-acre) field plots at an an ISU research farm. All nitrogen applications are made in the spring. Both subsurface and surface water samples are collected and tested for nitrates, phosphates, and bacteria.
After five years of data collection, researchers say they have some important answers.
"The key finding is that poultry manure applied at the 168-kg per ha (150-lb per acre) rate resulted in lower nitrate, phosphate, and bacteria concentrations in subsurface drainage water when compared with equivalent application rates of commercial nitrogen fertilizer," says ASAE member Ramesh Kanwar, chair of the ISU Agricultural and Biosystems Engineering Department and lead researcher on the project.
Kanwar says the research also shows that when poultry manure is applied at a much higher rate than is needed to meet the nitrogen-uptake needs of a crop, such as the application of poultry manure at the 136-kg (300-lb) rate, the impact on water quality is greater and crop yields don't increase significantly.
For more information contact Kanwar, 515-294-1434, email@example.com.