Soil Carbon Dynamics in Reclaimed Mining Lands: Insights from Organic Amendment Applications

The reclamation of degraded soils, particularly in tropical post mining areas, presents a significant challenge. Organic soil amendments are widely proved to improve soil health by increasing organic carbon accumulation in degraded soils, such as that in a tropical post-tin mining area. Their application also affects soil organic carbon (SOC) quality. However, a process of quality transformation induced by the organic soil amendments is still far from definite. Thus, this study aimed to explore the transformative potential of organic soil amendments in boosting SOC storage and enhancing its quality.

Over a four-year period, we conducted a comprehensive study in an Indonesian post-tin mining soil using a randomized block design with four replications. The treatments included control (no amendment), compost, charcoal, and a combination of charcoal and compost. Our findings revealed that organic amendments not only increased SOC stock but also induced significant changes in SOC quality, as evidenced by chemical composition analysis using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR). Notably, the charcoal treatment showed marked differentiation of SOC chemical composition from the second year onwards. By performing a two-dimensional correlation spectroscopic (2DCOS) analysis, we observed an intensive change in SOC quality transformation. The organic soil amendments facilitated soil microorganism activity and plant growth with the variety of carbon inputs, leading to enhanced lignin and ester accumulation. This study underscores the dual benefits of organic amendments in improving both the quantity and quality of SOC in degraded soils, offering a sustainable solution for soil reclamation.