|Edwards, D - UNIVERSITY OF KENTUCKY|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 14, 2005
Publication Date: December 1, 2005
Citation: Moore Jr., P.A., Edwards, D.R. 2005. Long-term effects of poultry litter, alum-treated litter and ammonium nitrate on aluminum availability in soils. Journal of Environmental Quality. 34:2104-2111. Interpretive Summary: The poultry industry results in a major economic benefit to several areas in the USA, however, there is concern that land application of poultry litter can lead to impaired water quality since it can result in high levels of phosphorus runoff. Treating poultry litter with alum has received considerable attention as an economically viable best management practice for reducing ammonia emissions from poultry houses and reducing phosphorus runoff from fields fertilized with litter. The objective of this study was to compare the long-term effects of alum-treated litter to normal poultry litter and ammonium nitrate. The results of this study showed that ammonium nitrate, the most common fertilizer in the world, resulted in very acid soil conditions, which made the soil aluminum available to forages, negatively effecting growth. In contrast, both alum-treated litter and normal litter increased soil pH (liming effect) and did not effect soil aluminum. Plant growth was greater with alum-treated litter than normal litter or ammonium nitrate. Since alum-treated litter has economic benefits for poultry production and reduces ammonia emissions and phosphorus runoff and does not cause problems with aluminum, it appears to be a more sustainable fertilizer source than either normal litter and/or ammonium nitrate.
Technical Abstract: Research has shown that alum (Al2(SO4)3 14H2O) applications to poultry litter can greatly reduce phosphorus (P) runoff, as well as decrease ammonia (NH3) volatilization. However, the long-term effects of fertilizing with alum-treated litter are unknown. The objectives of this study were to evaluate the long-term effects of normal poultry litter, alum-treated litter and ammonium nitrate (NH4NO3) on aluminum (Al) availability in soils, Al uptake by tall fescue, and tall fescue yields. A long-term study was initiated in April of 1995. There were 13 treatments (unfertilized control, four rates of normal litter, four rates of alum-treated litter and four rates of NH4NO3) in a randomized block design. All fertilizers were broadcast applied to small plots (3.05 x 1.52m) cropped to tall fescue (Festuca arundinacea Schreb.) annually in the spring. Litter application rates were 0, 2.24, 4.49, 6.73, and 8.98 Mg ha**-1 (0, 1, 2, 3, and 4 tons acre**-1); NH4NO3 rates were 65, 130, 195 and 260 kg N ha**-1 and were based on the amount of N applied with alum-treated litter. Soil pH, exchangeable Al (extracted with potassium chloride), Al uptake by fescue and fescue yields were monitored periodically over time. Ammonium nitrate applications resulted in reductions in soil pH beginning in year 3, causing exchangeable Al values to increase from less than 1 mg Al/kg soil in year 2 to over 100 mg Al/kg soil in year 7 for many of the NH4NO3 plots. In contrast, normal and alum-treated litter resulted in an increase in soil pH, which decreased exchangeable Al when compared to unfertilized controls. Severe yield reductions were observed with NH4NO3 beginning in year 6, which were due to high levels of acidity and exchangeable Al. Fescue yields were highest with alum-treated litter (annual average = 7.36 Mg Ha**-1), followed by normal litter (6.93 Mg Ha**-1), NH4NO3 (6.16 Mg Ha**-1), and the control (2.89 Mg Ha**-1). These data indicate that poultry litter, particularly alum-treated litter, may be a more sustainable fertilizer than NH4NO3.