Comparative assessment of selected micronutrients under three different land use systems in Odighi, Edo State, Nigeria

This study carried out a comparative assessment of selected micronutrients under mixed tree plantation, cassava and secondary forest land use systems in Odighi, Edo State, Nigeria. The objectives of the study were to determine the concentrations of selected micronutrients under each of the three land use systems; evaluate the distribution of these micronutrients among the three land use systems; and examine the impact of the three land use systems on the selected micronutrients. Using transect sampling design, 18 soil samples were collected from each of the three land use systems giving a total of 54 soil samples for the study. The cassava land use was 7-10-year-old, mixed tree plantation was 10-15-year-old, while secondary forest was 25-year-old and above. Results showed that the concentrations of the selected soil micronutrients (iron, copper, manganese, and zinc) increased with increasing soil depth in all the examined sites except for manganese under cassava land use. The status of iron and zinc were rated excess while copper and manganese were rated optimum for crop production. The study observed significant (p < 0.05) variations for iron and manganese contents across the examined land uses and concluded that the direction and magnitude of changes in the status of micronutrients were a reflection of long-term impact of the different land uses and soil management measures. Liming of the soil and limited use of nitrogen-containing fertilizers are recommended to ameliorate zinc toxicity in the study area. Also, farmers in collaboration with agriculture extension workers should regulate the usage of organic and inorganic fertilizers as soil treatments to avoid excessive concentrations of iron and zinc in the study area.