Aggregate characteristics and aggregate-associated soil organic carbon and carbohydrates of soils under contrasting tree land use

Bassey Udom (Department of Crop and Soil, University of Port Harcourt, P.M.B. 5323, Port Harcourt)
Joshua Ogunwole (Bowen University, Iwo, P.M.B. 284, Osun State)
Chima Wokocha (Department of Crop and Soil, University of Port Harcourt, P.M.B. 5323, Port Harcourt)

SAINS TANAH - Journal of Soil Science and Agroclimatology
Vol 18, No 2 (2021): December

Protection of soil organic carbon and acid-hydrolyzable carbohydrates in aggregate-size fractions is important for appraising soil degradation and aggregation under land use types. Aggregate-associated soil organic carbon (SOC) and acid-hydrolyzable carbohydrates (R-CHO) in bulk soils and aggregate-size fractions of a sandy loam soil under Alchornea bush, Rubber, Oil palm and Teak plantations in southern Nigeria were studied. Results revealed significant differences in aggregate-associated SOC and R-CHO, bulk densities, total porosity, soil organic carbon stock and aggregate stability among the land use types. Greater SOC was stored in macro-aggregates >0.25 mm, while greater R-CHO was occluded in micro-aggregates <0.25 mm (p<0.05). The highest mean weight diameter (MWD) was 1.01 mm in Alchornea soils and 0.92 mm in Oil palm plantation at 0-15 cm topsoil. Soil organic carbon stock in 0-15 cm topsoil was 77.7, 81.8, 92.2, and 67.5 kg C ha-1 in Alchornea, Rubber, Oil palm, and Teak soils, respectively. Relationships showed a positive linear correlations between MWD and SOC (r = 0.793, p < 0.05) and R-CHO (r = 0.789. p < 0.05). Alchornea bush and Oil palm plantation increased macro-aggregate formation and macro-pores >5 µm, therefore they have greater potentials to boost protection of SOC in soil macro-aggregates.