Influence of Biochar Organic Carbon Composition and Thermal Stability on Nitrate Retention and Tomato Yield on Soilless Biochar Amended Growth Media

George K. Osei, Lucy W. Ngatia (), Michael D. Abazinge, Alejandro Bolques, Charles Jagoe, Marcia A. Owens, Benjamin Mwashote and Riqiang Fu
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George K. Osei: School of Environment, Florida Agricultural & Mechanical University, Tallahassee, FL 32307, USA
Lucy W. Ngatia: College of Agriculture and Food Sciences, Florida Agricultural & Mechanical University, Tallahassee, FL 32307, USA
Michael D. Abazinge: School of Environment, Florida Agricultural & Mechanical University, Tallahassee, FL 32307, USA
Alejandro Bolques: School of Environment, Florida Agricultural & Mechanical University, Tallahassee, FL 32307, USA
Charles Jagoe: School of Environment, Florida Agricultural & Mechanical University, Tallahassee, FL 32307, USA
Marcia A. Owens: School of Environment, Florida Agricultural & Mechanical University, Tallahassee, FL 32307, USA
Benjamin Mwashote: School of Environment, Florida Agricultural & Mechanical University, Tallahassee, FL 32307, USA
Riqiang Fu: National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA

Agriculture, 2025, vol. 15, issue 8, 1-18

Abstract: The application of biochar to traditional soil and soilless growth media in agriculture has been reported to increase plant production. However, it remains unclear which biochar component drives this process or which biogeochemical process is attributed to better plant productivity. Therefore, this study aims to determine how biochar organic carbon (C) composition and thermal stability influence nitrogen availability and tomato production. Soilless growth media composed of a mixture of 60% and 40% coconut coir (CC) ( Cocos nucifera L.) and fine pine bark (PB) ( Pinus genus ), respectively, was amended with 0, 1, 2, 3, 4, 6, 8, 10, and 12% biochar per dry weight. The amended media were used to grow Red Bounty tomatoes ( Lycopersicum esculentum ) for three months. After harvesting tomatoes and determining yield, organic C composition and C thermal stability of the biochar amended soilless growth media mixtures were determined using solid-state 13 C nuclear magnetic resonance ( 13 C NMR) and multi-elemental scanning thermal analysis (MESTA), respectively. Thermal stability data were used to determine the “R400 index”, and nitrate (NO 3 − ) concentration was determined using the water extractable method. Results showed that biochar-amended media significantly increased pH ( p < 0.0001) and NO 3 − ( p = 0.0386) compared to the no-char control. Biochar amended soilless media organic C composition was dominated by O-alkyl-C as a result of a higher fraction of soilless media; however, total C, carboxyl-C, phenolic-C, and aromatic-C increased with increasing biochar content and related negatively to R400, which decreased with increasing biochar content. Nitrate retention and tomato yield increased with increasing total C, carboxyl-C, phenolic-C, and aromatic-C and decreasing R400. This indicates that the stable form of C, carboxyl-C, phenolic-C, aromatic-C, and low R400 enhanced NO 3 − sorption, reducing leaching and enhancing its availability for tomato growth.

Keywords: biochar; carbon stability; carbon thermal stability; R400 index; soilless growth media (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2025
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