Investigating the impact of broiler litter application method and biochar on phosphorus leaching

Authors: BRAR, GURPARSHAD - Auburn University; MALHOTRA, KRITIKA - University Of Southern California; KUMAR, RAKESH - Auburn University; LAMBA, JASMEET - Auburn University; Way, Thomas; PRASAD, RISHI - Auburn University; ADHIKARI, SUSHIL - Auburn University

Submitted to: Water, Air, and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2025
Publication Date: 6/5/2025
Citation: Brar, G., Malhotra, K., Kumar, R., Lamba, J., Way, T.R., Prasad, R., Adhikari, S. 2025. Investigating the impact of broiler litter application method and biochar on phosphorus leaching. Water, Air, and Soil Pollution. 236(558). https://doi.org/10.1007/s11270-025-08177-7.
DOI: https://doi.org/10.1007/s11270-025-08177-7

Interpretive Summary: Manure from broiler chickens contains phosphorus, which can be detrimental to water quality when delivered to water bodies through the presence of macropores in soil. The objectives of this study were to examine the effectiveness of different application methods (surface vs. subsurface) of broiler litter and pine wood pristine biochar on the leaching of dissolved reactive phosphorus (DRP) via preferential flow. Cylindrical soil cores, 15 cm diameter and 50 cm depth, were collected from the sandy loam soil of a pasture in northeastern Alabama. In the lab, we simulated rainfall by irrigating the soil surface of each core, and leachate water was collected after it flowed down through each soil core. The results showed preferential flow in the cores due to the presence of macropores. The treatments we used on the soil cores in the lab were (1) surface-applied broiler litter, (2) subsurface-banded broiler litter, (3) surface-applied broiler litter + biochar, (4) subsurface-banded broiler litter + biochar, and (5) control (no biochar and no broiler litter). For each treatment, three rainfall simulations were performed: simulation 1 (0th day), simulation 2 (5th day), and simulation 3 (10th day). Treated cores leached significantly greater amounts of dissolved reactive phosphorus (DRP) than control cores. However, DRP leaching decreased with successive rainfall events. The subsurface banding application method was more effective than surface broadcasting in controlling DRP leaching.

Technical Abstract: Phosphorus can be detrimental to water quality when delivered to water bodies through the presence of macropores in soil. The objectives of this study were to examine the effectiveness of different application methods (surface vs. subsurface) of broiler litter and pine wood pristine biochar on the leaching of dissolved reactive phosphorus (DRP) via preferential flow. Cylindrical soil cores, 15 cm diameter and 50 cm depth, were collected from the sandy loam soil of a pasture in northeastern Alabama, and used for a rainfall simulation experiment in the lab. Treatments were surface-applied broiler litter, subsurface-banded broiler litter, surface-applied broiler litter + biochar, subsurface-banded broiler litter + biochar, and control (no biochar and no broiler litter). For each treatment, three rainfall simulations were performed: simulation 1 (0th day), simulation 2 (5th day), and simulation 3 (10th day). Bromide breakthrough curves provided evidence of preferential flow down through the soil for all soil cores. Treated cores leached significantly greater amounts of dissolved reactive phosphorus (DRP) than control cores. However, DRP leaching decreased with successive rainfall events. The subsurface banding application method was more effective than surface broadcasting in controlling DRP leaching.