Cement Kiln Dust Combined with Digestate and Humic Acid for GHG Mitigation and Soil Improvement

This study addresses the dual challenge of industrial waste management and agricultural sustainability by repurposing Cement Kiln Dust, a substantial alkaline by-product, alongside organic amendments (digestate and humic acid) in Gray Luvisolic soil. This research focuses on these materials as they offer a valuable, high-impact alternative to costly conventional liming and resource depletion, fulfilling the need for circular economy strategies. The core objective was to determine the efficacy of this integrated waste-reuse approach on enhancing soil functional properties and suppressing potent greenhouse gas emissions (CO2, N2O, and CH4). A Randomized Complete Block experimental design was used to quantify gas efflux rates using static chamber method and analyzing soil properties at harvest. Results confirmed significant biological enhancement (p < 0.05); the treatment combining reapplied Cement Kiln Dust and 50% chemical fertilizer produced a 109% increase in Microbial Biomass Nitrogen over the control. While cumulative gas fluxes were not statistically significant (p > 0.05), the best combination, reapplied Cement Kiln Dust with 50% fertilizer and digestate, yielded a notable 60.2% lower mean N2O flux. It is concluded that utilizing these by-products is highly effective for significantly improving soil microbial biomass and correcting soil acidity, warranting further research into the strong directional trend toward reducing agricultural N2O emissions.