Exploring the mystery of soil carbon mineralization: Insights from incubation experiments and kinetic modeling

Abstract

Soil carbon mineralization is vital for carbon sequestration but affected by factors like soil type and residue quality. Understanding the process and factors is still incomplete, including the interplay between soil properties and organic residues and the need for accurate kinetic models. Research faces significant challenges in describing carbon mineralization dynamics. The present study aimed to investigate carbon mineralization in three soils located in Tamil Nadu, India (S1, S2 and S3) that possess distinct textures. The study also focused on the effects of five different plant residues (Rice, maize, sugarcane, cotton and turmeric) on carbon mineralization in these soils. Incubation experiments were conducted for 150 days, and CO2 evolution was measured at different time intervals of 7, 10, 15, 30, 60, 90, 120 and 150 days. The performance of three kinetic models (Zero order model, exponential kinetic model and first order model) was also evaluated in predicting carbon mineralization using experimental data. The results showed that the rate and extent of carbon mineralization varied significantly among the different soils and residues. The highest carbon mineralization was observed in rice (989.02 µg C/g/day) and maize (966.53 µg C/g/day) residue, while the lowest was in sugarcane (752.09 µg C/g/day) residue. Among the kinetic models, the first-order kinetic model provided the best fit for all treatments (R2=0.98). The findings suggest that soil texture and residue quality play crucial roles in carbon mineralization. The first order kinetic model can be useful for predicting carbon mineralization in different soil-residue systems. These results have implications for managing soil carbon sequestration and mitigating climate change.