Soil Macrofauna as Bioindicators of Soil Fertility in Cocoa Plantations Theobroma cacao L.) at Different Elevations in Kota Komba Subdistrict, East Manggarai Regency

Cocoa (Theobroma cacao L.) thrives in tropical regions, including the Kota Komba subdistrict. However, knowledge and utilization of soil macrofauna as bioindicators of soil fertility remain limited, resulting in suboptimal land management practices that impact cocoa productivity and sustainability. This study aims to analyze the diversity of soil macrofauna and its role as a bioindicator of soil fertility in cocoa plantations in the Kota Komba subdistrict. Samples were collected from three locations at different elevations: 125 m above sea level, 435 m above sea level, and 856 m above sea level. The sampling method used was direct observation in the cocoa plantation. Soil macrofauna samples were collected using pitfall traps and hand sorting, while soil samples were analyzed to determine organic carbon content, pH, cation exchange capacity (CEC), and base exchange capacity (BEC). Diversity index (H'), abundance index (R1), and dominance index (C) were calculated to analyze macrofauna diversity. Data were analyzed using SPSS ANOVA BNT software to test macrofauna as bioindicators of soil fertility. The results showed that 11 soil macrofauna species from 3 phyla were found, with the highest diversity at an altitude of 435 m above sea level (11 species), followed by 125 m above sea level (10 species), and 856 m above sea level (7 species). The diversity index (H') ranged from 1.761 to 2.203 (moderate category), with the highest value at 435 m above sea level, and the evenness index (E) ranged from 0.905 to 0.937 (high category). pH and organic carbon significantly influenced (p<0.05) macrofauna diversity, while CEC and base saturation were not significant (p>0.05). Soil macrofauna has proven to be an effective bioindicator of soil fertility due to its sensitivity to edaphic conditions and its role in bioturbation, organic matter decomposition, and soil structure formation. A stable macrofauna community (E > 0.9) indicates a balanced soil ecosystem and can be used as a practical bioindicator for assessing the fertility of cocoa plantation soils.