Phosphorus leaching from soil cores from a twenty-year study evaluating alum treatment of poultry litter

Authors: ANDERSON, KELSEY - University Of Arkansas; Moore, Philip; MILLER, DAVID - University Of Arkansas; DELAUNE, PAUL - Texas A&M Agrilife; EDWARDS, DWAYNE - University Of Kentucky; Kleinman, Peter; CADE-MENUN, BARBARA - Agriculture And Agri-Food Canada; Miles, Dana

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2018
Publication Date: 5/3/2018
Citation: Anderson, K.R., Moore Jr, P.A., Miller, D.M., DeLaune, P.B., Edwards, D.R., Kleinman, P.J., Cade-Menun, B.J., Miles, D.M. 2018. Phosphorus leaching from soil cores from a twenty-year study evaluating alum treatment of poultry litter. Journal of Environmental Quality. 47:530-537.

Interpretive Summary: Alum (aluminum sulfate) additions to poultry litter is a best management practice used to precipitate phosphorus into less soluble forms, which results in less phosphorus runoff from fields fertilized with poultry litter. However, little is known about the effects of alum-treated poultry litter on phosphorus leaching. The objective of this study was to investigate the effects of alum-treated poultry litter and untreated poultry litter on phosphorus leaching from soil cores taken from plots that had been fertilized with litter for 20 years. Two soil cores were taken from plots in a study with 13 treatments; a control, four rates of untreated and alum-treated litter and four rates of ammonium nitrate. One of the cores from each plot was fertilized with the same fertilizer it had received for 20 years and the other core was a control core. Phosphorus leaching from the cores was measured for one year. The average soluble phosphorus concentrations in the leachate varied from 0.16 to 0.41 mg P L-1 in the fertilized alum-treated cores, whereas the fertilized untreated litter ranged from 0.40 to 2.53 mg P L-1 . At the highest litter rate (four tons/acre-yr), alum reduced soluble and total phosphorus concentrations in leachate by 84% and 86%, respectively, compared to untreated litter. These results indicate that adding alum to poultry litter has a positive legacy effect on phosphorus; significantly reducing both soluble and total phosphorus concentrations and loads in leachate.

Technical Abstract: Adding alum (aluminum sulfate) to poultry litter is a best management practice (BMP) used to stabilize phosphorus (P) in less soluble forms, reducing non-point source P runoff. However, little research has been conducted on the effects of alum-treated poultry litter on P leaching. The objective of this study was to evaluate the effects of alum-treated versus untreated poultry litter on P leaching from soil cores receiving long-term poultry litter applications. Two soil cores were taken from 52 plots in a small plot study with 13 treatments; a control, four rates of untreated and alum-treated litter (2.24, 4.49, 6.72, and 8.96 Mg ha-1) and four rates of ammonium nitrate (65, 130, 195, and 260 kg N ha-1). One of the cores from each plot was fertilized with the same fertilizer it had received for 20 years (FT) core and the other core was a control (CT) core (total of 25 treatments). Phosphorus leaching was measured for one year. The average SRP concentrations in the leachate varied from 0.16 to 0.41 mg P L-1 in the fertilized alum-treated cores, whereas the fertilized untreated litter ranged from 0.40 to 2.53 mg P L-1 . At the highest litter rate (8.96 Mg ha-1), alum reduced SRP and TP concentrations in leachate by 84% and 86%, respectively, compared to untreated litter. These results indicate alum additions to poultry litter have a legacy effect on P and significantly reduce both SRP and TP concentrations and loads in leachate.