Impact of land-use systems on some physical and chemical soil properties of an oxisol in the humid forest zone of Southern Cameroon.

摘要

A field study was carried out in the village Ngoungoumou in the humid forest zone of Cameroon to assess changes in particle size distribution and soil chemical properties in relation to different land-use systems. These strongly acid soils are mainly composed of clay and sand, and are generally devoid of crop nutrients at the benefit of exchangeable Al occupying the nearly entire exchange complex. The major portion of the nutrients is stored in the top-soil, together with the organic matter. Land-use systems significantly affected the clay, the silt and the sand fractions. Sand and silt decreased with the soil depth whereas clay increased with it. Soil pH, total N, organic carbon, available P, exchangeable Ca, exchangeable Al, sum of bases, ECEC and Al saturation significantly differed with the land-use systems. Al saturation increased with soil depth, and the top-soils presented acidity problems while the sub-soils exhibited Al toxicity. Chromolaena odorata fallows presented relative higher soil fertility, secondary forests and cocoa plantations the lower. Utilization of harvest residues, wood ash or lime; Ca, N, P, K and Mg fertilizations according to crop requirement; acid-tolerant crops and N fixing trees for acid soils appear to be the most appropriate soil management options.