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Padilla JT, Watts DW, Novak JM, Cerven V, Ippolito JA, Szogi AA, Johnson MG. Magnesium activation affects the properties and phosphate sorption capacity of poultry litter biochar. BIOCHAR 2023; 5:1-14. [PMID: 38269399 PMCID: PMC10805231 DOI: 10.1007/s42773-023-00263-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 09/19/2023] [Accepted: 09/22/2023] [Indexed: 01/26/2024]
Abstract
Biochars with a high affinity for phosphorus (P) are promising soil amendments for reducing P in agricultural run-off. Poultry litter (PL) is an abundant biochar feedstock. However, PL-derived biochars are typically high in soluble P and therefore require chemical modification to become effective P sorbents. This study investigated the effect of magnesium (Mg) activation on extractable P (EP) and P sorption capacities of PL-derived biochars. Biochar was produced at 500-900 °C from PL activated with 0-1 M Mg. Three differentially aged PL feedstocks were evaluated (1-, 3-5-, and 7-9-year-old). Increased Mg activation level and pyrolysis temperature both resulted in EP reductions from the biochars. Specifically, biochars produced at temperatures ≥ 700 °C from PL activated with ≥ 0.25 M Mg had negligible EP. X-ray diffractograms indicated that increased Mg loading favored the formation of stable Mg3(PO4)2 phases while increasing temperature favored the formation of both Mg3(PO4)2 and Ca5(PO4)3OH. Maximum P sorption capacities (Pmax) of the biochars were estimated by fitting Langmuir isotherms to batch sorption data and ranged from 0.66-10.35 mg g-1. Average Pmax values were not affected by PL age or pyrolysis temperature; however, biochars produced from 1 M Mg-activated PL did have significantly higher average Pmax values (p < 0.05), likely due to a greater abundance of MgO. Overall, the results demonstrated that Mg activation is an effective strategy for producing PL-derived biochars with the potential ability to reduce P loading into environmentally sensitive ecosystems.
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Affiliation(s)
- Joshua T. Padilla
- United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water and Plant Research Center, Florence, SC 29501, USA
| | - Donald W. Watts
- United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water and Plant Research Center, Florence, SC 29501, USA
| | - Jeffrey M. Novak
- United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water and Plant Research Center, Florence, SC 29501, USA
| | - Vasile Cerven
- United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water and Plant Research Center, Florence, SC 29501, USA
| | - James A. Ippolito
- School of Environment and Natural Resources, The Ohio State University, Columbus, OH 43210, USA
| | - Ariel A. Szogi
- United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water and Plant Research Center, Florence, SC 29501, USA
| | - Mark G. Johnson
- Center for Public Health and Environmental Assessment, United States Environmental Protection Agency, Corvallis, OR 97331, USA
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