ABSTRACT

The amount of soil organic carbon (SOC) stored in a particular soil is influenced by several factors including climate, vegetation type and age, land management, soil properties and current and past land use. The impacts of land use types on soil organic carbon were assessed.

Four land use types were used in the study. Sampled soils were taken at depth of 0-45 cm and at intervals of 15 cm. The soil samples were examined in accordance with the standard methods. The data were analyzed using descriptive statistics. The findings revealed that the textural classes were silty clay, silty clay loam and clay loam. The first two classes were common to all locations and the last class was occurred only in University oil plantation. The results showed that mean soil organic carbon content was higher under the oil palm plantation land use [D] compared with other land use types at 0 - 15 cm soil depth (2.87 g kg^-1), which was 11.5, 20.2 and 76.0 %% more than in the Faculty of Agriculture Teaching and Research farm land A], the cashew· plantation land [B] and the Agricultural and Bioresources experimental farm land [C] respectively. This could be attributed to greater inputs of vegetation (litter fall) and reduced decomposition of organic matter. Similarly, the lowest soil organic carbon content under land use type C could be due to reduced inputs of organic matter and frequent tillage which encouraged oxidation of organic matter. The finding indicated that the means of SOC in land use types were no significantly different (P = 0.05) except land use type C. The soil bulk density showed significant variation (P < 0.05) with the soil depth. These results indicated that soil bulk density increases with decreases soil organic carbon and porosity. The soil porosity content variation with land use types was attributed to variation in soil organic carbon and soil texture. Conclusively, land use type influenced soil organic carbon content.