Effect of poultry litter application and preferential flow on metal loss in pastures

Authors: MALHOTRA, KRITIKA - Auburn University; LAMBA, JASMEET - Auburn University; Way, Thomas; PRASAD, RISHI - Auburn University; SRIVASTAVA, PUNEET - University Of Maryland

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2025
Publication Date: 7/12/2025
Citation: Malhotra, K., Lamba, J., Way, T.R., Prasad, R., Srivastava, P. 2025. Effect of poultry litter application and preferential flow on metal loss in pastures. Journal of Environmental Management. 391:126415. https://doi.org/10.1016/j.jenvman.2025.126415.
DOI: https://doi.org/10.1016/j.jenvman.2025.126415

Interpretive Summary: Water flow through soil is important for providing infiltration to deliver rain and irrigation water to crop roots, and for reducing runoff water. However, this flow can have detrimental environmental effects, as it allows nutrients and other solutes to be transported by subsurface water flow away from the field area to which they are applied. Cylindrical soil samples (columns), 15 cm diameter and 50 cm depth, were collected from the fine sandy loam soil of a pasture field in northeastern Alabama. In the laboratory we broadcast-applied broiler litter, which is a mixture of chicken manure and a bedding material, on the soil surface of half of the columns. We simulated rainfall by sprinkling water on the soil surface of each column. Leachate water was collected after it flowed down through the soil columns. We measured concentration of metals (Al, B, Ca, Mg, Mn, Na, and Zn) in the leachate water which flowed out from the bottoms of the columns. These results are expected to be useful in analyzing the movement of metals in water through soil, and in promoting the accuracy and usefulness of computer modeling to improve agricultural productivity and reduce environmental contamination.

Technical Abstract: Large amounts of poultry litter, which is a mixture of manure and a bedding material, are produced by the expanding poultry industry in the southeastern United States and are applied to pasture lands as an organic fertilizer. Apart from essential plant nutrients (N-P-K), poultry litter also contains other nutrients and trace or heavy metals, yet little is known about the potential of these metals to leach from no-till pasture soils. Therefore, this research aimed to quantify the subsurface loss of several metals (i.e., Al, B, Ca, Mg, Mn, Na, and Zn) from a tall fescue pasture and determine if preferential flow paths enhance the mobility of these metals through the soil. A rainfall simulation study was conducted on six undisturbed soil columns collected from a field located at the Sand Mountain Research and Extension Center in Alabama. Poultry litter was applied at two rates: 0 (control) and 5 Mg ha-1 (treatment). Leachate metal concentrations were measured, and bromide breakthrough curves (BTCs) were analyzed to assess the degree of preferential flow. A sequential extraction procedure was used for recognizing metals in the following seven fractions categorized: soluble, exchangeable, bound to carbonates, bound to amorphous oxides, bound to crystalline oxides, bound to organic matter, and residual. The shape of the BTCs and other solute transport parameters, such as early breakthrough and immobile pore-water fraction, provided direct evidence of preferential flow in all the columns. Flow-weighted mean concentrations of B, Na, and Zn in the leachate differed significantly between the control and treatment columns. However, poultry litter had no significant effect on the leaching metal losses, with the exception of Na. Eluted total metal loadings in the treatment columns varied in the following sequence: Ca > Mg > Na > Zn > Mn > Al > B. The BTCs of metals also indicated the presence of preferential flow. The study demonstrates that despite the sorptive nature of metals, their transport from poultry litter application could be enhanced under preferential flow conditions. Although the leaching losses of some of the metals in this study did not increase substantially with poultry litter application, their retention in soil suggests the potential of poultry litter to accelerate the subsurface transport of these metals if the soil becomes metal-contaminated with the litter application over an extended period of time. These findings have important implications for the safe and sustainable management of poultry litter application on pasture soils.