Investigating the effect of animal manure on colloidal-facilitated phosphorus transport

Authors: MALHOTRA, KRITIKA - University Of Southern California; LAMBA, JASMEET - Auburn University; Way, Thomas; WILLIAMS, COLLEEN - University Of Wisconsin; KARTHIKEYAN, K - University Of Wisconsin; PRASAD, RISHI - Auburn University; SRIVASTAVA, PUNEET - University Of Maryland; ZHENG, JINGYI - Auburn University

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2025
Publication Date: 2/24/2025
Citation: Malhotra, K., Lamba, J., Way, T.R., Williams, C., Karthikeyan, K.G., Prasad, R., Srivastava, P., Zheng, J. 2025. Investigating the effect of animal manure on colloidal-facilitated phosphorus transport. Geoderma. 455:117203. https://doi.org/10.1016/j.geoderma.2025.117203.
DOI: https://doi.org/10.1016/j.geoderma.2025.117203

Interpretive Summary: Land areas with intensive livestock production often contain soils enriched with phosphorus (P) caused by repeated application of animal manure. Colloids are suspensions of well-dispersed very small particles, with dimensions of 1 nm to 1 µm. Colloids can facilitate P transport within soil, thereby aiding P movement via surface runoff and subsurface flow. This can lead to environmental issues including algal blooms and eutrophication of water bodies. 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 one of these on the soil surface of each column: poultry litter (a solid mixture of manure and a bedding material), dairy manure (semi-solid), and swine lagoon effluent (liquid). We simulated rainfall by irrigating the soil surface of each column. Leachate water was collected after it flowed down through each soil column. Colloidal P contributed from 5 to 49% of total P leaching from the columns. Our results show that colloidal-facilitated migration of P can be substantial and should be considered when elucidating P transport in agricultural systems fertilized with animal manure.

Technical Abstract: Preferential flow via soil macropores can enhance phosphorus (P) loss in leachate. The application of animal manure can further exacerbate P losses in leachate in various forms. Limited work has been done to quantify colloidal-facilitated-P loss in leachate as a function of manure type. Therefore, the goal of this study was to determine the impact of three manure types, namely, poultry litter, swine lagoon effluent, and dairy manure, on P leaching in various forms using column-based rainfall simulation experiments. Intact-undisturbed soil columns were collected from a pasture field located in Alabama, USA. The overall experimental design included four treatments with two replications each (poultry litter (solid) at rate 1 (5 Mg/ha), poultry litter (solid) at rate 2 (10 Mg/ha), dairy manure (semi-solid), and swine lagoon effluent (liquid) and unamended control). The bromide breakthrough curves showed evidence of preferential flow. The flow-weighted mean total P concentrations for treatment columns ranged from 5.4 to 6 mg/L, 6.22 to 12.18 mg/L, 0.95 to 1.42 mg/L, and 0.29 to 1.1 mg/L for columns treated with solid poultry litter at rate 1, solid poultry litter at rate 2, swine lagoon effluent, and dairy manure, respectively. The colloidal P contributed from 5 to 49% of total P leaching from the treatment columns. Therefore, the results of this study show that colloidal-facilitated migration of P can be significant and should be considered when elucidating P transport in agricultural systems fertilized with animal manure.