Micronutrient Concentrations and Environmental Concerns in an Intensively Cultivated Typic Dystrandept in Mount Bambouto, Cameroon

Micronutrient status of top soils (0 - 25 cm) collected from intensively cultivated soils (typic dystrandept) in the Bambouto highland of Cameroon was investigated. Thirty-six soil samples were collected within a 100 m 100 m grid. 16 of them were analyzed for pH, organic carbon, cation exchange capacity (CEC), Total N (totN), available P, exchangeable K, Ca and Mg, and 36 samples were analyzed for Cu, Mn, Fe and Zn. The status of trace elements was compared with soil critical levels and soil-based risk thresholds, and was declared deficient, sufficient or toxic. The soils were generally, slightly acidic, of high organic and nitrogen status and of adequate concentrations in exchangeable bases and available P. Mean values of Fe, Cu, Mn and Zn were 58.59, 0.52, 29.20 and 4.99 ppm, respectively. Relative to critical levels, 53% and 8% of the soils examined were deficient in Cu and Zn respectively while in all soils, Fe and Mn were above critical levels. The concentrations of the micronutrients investigated (except for Fe in 3% of the soils) were lower than toxic thresholds prescribed by European Economic Community (EEC) and the United States Environmental Protection Agency. Farmers' current level of agricultural intensification has no threats on micronutrient toxicity. However, because of Cu and Zn deficiency observed in some fields, an analysis of spatial variability is required to guide site specific soil nutrient management. Furthermore, in order to obtain quality produce and protect the environment, a balanced fertilizer recommendation including NPK + Cu + Zn is required for intensively cultivated typic dystrandept soils in the Bambouto highlands.