Lime equivalence values of nineteen biochar products made from defatted cottonseed meal, poultry litter and woody sources for quality assessment

Authors: ADEWUMI, OLANIYI - Delaware State University; He, Zhongqi; DHANDAPANI, RENUKA - Cotton, Inc; GUO, MINGXIN - Delaware State University

Submitted to: Agricultural & Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2025
Publication Date: 5/5/2025
Citation: Adewumi, O., He, Z., Dhandapani, R., Guo, M. 2025. Lime equivalence values of nineteen biochar products made from defatted cottonseed meal, poultry litter and woody sources for quality assessment. Agricultural & Environmental Letters. 10(1). Article e70017. https://doi.org/10.1002/ael2.70017.
DOI: https://doi.org/10.1002/ael2.70017

Interpretive Summary: Lime equivalence is a major characteristic for evaluating the quality of biochar as a soil amendment. This work determined the lime equivalence values, expressed in calcium carbonate equivalent (CCE), of 19 biochar products derived from diverse feedstock materials with different pyrolysis conditions, and analyzed their correlations with the relevant physicochemical parameters (i.e., pH, organic matter content, mineral ash contents, and soluble base cations). Specifically, this work assessed the acid-neutralizing capacity of biochar products and determine dthe factors that influence their potential for functioning as reliable soil liming materials. Thus, information derived from this work would shed light on biochar product optimization and appraisals for preferably rectifying strongly acidic soils via efficiently neutralizing soil acids, raising soil pH, and enhancing soil health and productivity.

Technical Abstract: The lime equivalence, expressed in calcium carbonate equivalent (CCE), is an important quality parameter of biochar as a soil amendment. This work measured the CCE values and relevant physiochemical parameters of seven defatted cottonseed meal-, seven poultry litter, and five wood-based biochar products. The CCE values of the 19 biochar samples covered a wide range of values from 2.75 to 128.0 g CaCO3 kg-1. Furthermore, the lime equivalence showed a weak but significant correlation with the pH parameter (r=0.5457, p<0.05), but not significant (p>0.05) with the other four measured parameters of organic content, ash content, electric conductivity, and sum of soluble base cations. As biochar products with greater lime equivalence have the advantages to substantially reduce soil acidity and improve soil fertility, information derived from this work would shed light on biochar product optimization and appraisals for preferably rectifying strongly acidic soils via efficiently neutralizing soil acids, raising soil pH, and enhancing soil health and productivity.