Characterization of poultry litter biochar and activated biochar as a soil amendment for valorization

Authors: KATUWAL, SHEELA - University Of Arkansas; Ashworth, Amanda; RAFSAN, NUR-AL-SARAH - North Carolina State University; PRAVEEN, KOLAR - North Carolina State University

Submitted to: Biomass
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2022
Publication Date: 9/21/2022
Citation: Katuwal, S., Ashworth, A.J., Rafsan, N., Praveen, K. 2022. Characterization of poultry litter biochar and activated biochar as a soil amendment for valorization. Biomass. 2(4):209-223. https://doi.org/10.3390/biomass2040014.
DOI: https://doi.org/10.3390/biomass2040014

Interpretive Summary: With the production of over 9 billion broiler (meat) chickens annually, poultry farming in the U.S. generates more than 30 billion lbs of poultry litter each year. Currently, most of the litter produced is surface applied to agricultural lands as a fertilizer. Raw poultry litter consists of approximately 3% nitrogen and phosphorus and applications based on crop nitrogen needs leads to excessive application of phosphorus. Consequently, during land application, losses occur through runoff and leaching to nearby water bodies thus causing water quality issues. Therefore, researchers set out to devise environmentally and economically sustainable management strategies for creating a value added product, one which creates electricity while creating a soil amendment with targeted nutrient contents, thereby ensuring the sustainability of the poultry industry. Conversion of poultry litter to biochar, which is a carbon rich by-product of bioenergy production, has proven to enhance soil's ability to hold water and can serve both the purposes of reducing the environmental concerns associated with the disposal of raw litter by targeting its nutrient composition (reducing soluble phosphorus and increasing nitrogen) and converting it into useful value-added product for use as soil amendment while creating energy. Researchers tested several production conditions of poultry litter biochar and found that under optimum production conditions, poultry litter biochar can improve soil amendment characteristics and subsequent soil and environmental health, while providing a renewable energy source.

Technical Abstract: Biochar applications to soils may enhance soil quality, hydrological properties, and agronomic productivity. Modification of biochar by activation via introduction of heteroatoms at different pyrolysis conditions can alter physical and chemical characteristics, which may enhance soil properties, although the extent of this is unknown. The objective of this study was to investigate the impacts of pyrolysis temperature (400, 500, 600, and 700') on activated (activated with methanesulfonic acid) and unactivated biochar produced from poultry litter to identify optimum production conditions for end use as a soil amendment. Physical, chemical, and surface properties of biochars were determined using wet chemistry and spectroscopic analyses. Results show that activation with methanesulfonic acid increased biochars’ oxygen content, while decreasing its point of zero charge and electrical conductivity. Conversion of raw poultry litter to activated and unactivated biochar increased concentration of P (3-fold), K (1.8-fold), Ca (3-fold), Mg (2.3-fold), and S (4.8- fold), with concentrations increasing with increasing temperatures (p < 0.05) except for C and N. Activated biochar had lower recovery of C and N, but greater water-holding capacity than unactivated biochar. Concentrations of NH4-N, NO3-N, and water-soluble P were greater in unactivated biochar (p < 0.05). Among all biochars, activated biochar produced at 400' had the lowest bulk density, total P, K, Ca, and Mg and greatest water-holding capacity, water-soluble P, Ca, and Mg concentrations, thereby suggesting improved soil amendment characteristics and subsequent soil health under poultry litter biochars produced under these conditions.