Effect of land management practices on soil organic carbon in the mangrove ecosystem

Abstract

This study assessed the distribution of soil organic carbon among soil fractions in a mangrove ecosystem in the Ilaje Area of Ondo State, southwestern Nigeria. Soil samples were collected from cultivated, regenerated, and natural forest lands at depths of 0 to 20 cm, 20 to 40 cm, and 40 to 60 cm. Sampling was conducted at three points along the diagonal of 20 m × 20 m plots established on three transects spaced 100 m apart within each site, using a 3 cm diameter soil auger. Soil organic carbon and selected physicochemical properties were determined using standard laboratory procedures. Total organic carbon (TOC) ranged from 5.70 ± 0.52% in cultivated land at 20 to 40 cm depth to 12.37 ± 1.50% in natural forest at the same depth. TOC differed significantly (P < 0.05) among land management practices but showed no significant variation with soil depth. POC and mineral-associated organic carbon (MOC) were also strongly influenced by land use, with POC values ranging from 3.21 ± 0.37% in cultivated land to 6.42 ± 0.36% in natural forest at 20 to 40 cm depth. Soil pH was moderately acidic across all depths and land uses, varying from 4.24 ± 0.10 to 5.38 ± 0.06. Overall, the findings underscore the significant role of land management practices in regulating soil organic carbon dynamics and related soil properties in mangrove ecosystems.