STATUS OF AVAILABLE MICRONUTRIENTS OF THE BASEMENT COMPLEX ROCK – DERIVED ALFISOLS IN NORTHERN NIGERIA SAVANNA.

The contents of available boron, zinc, copper, iron and manganese were determined in twenty surface soils (0-30cm depth) and profile pits collected from Northern Guinea and Sudan savanna zones which are the major tomato and horticultural crops growing areas of northern Nigeria savanna. The contents of available B from surface soils, extracted with hot water, varied from 0.04 – 0.28 with a mean of 0.14 mg kg-1, while Zn, Cu, Fe  and Mn, extracted with 0.1N HCl, varied from 1.8 –10.5, 1.0 –  9.0, 2.5 –75 and 2.8 – 18 mg kg-1, with  means of 4.2, 2.9, 19.6 and 9.2 mg kg-1 respectively. The contents of B, Zn, Cu, Fe and Mn in the profile pits ranged from 0.08 – 0.18, 1.5 – 3.5, 0.9 – 3.3, 14 – 26.2 and 11.2 – 20.5 mg kg-1 with means of 0.12, 2.4, 1.9, 20.7 and 15.0mg kg-1 respectively. Boron is deficient in all the soils; Zn is deficient in only some of the soils, while the contents of the other micronutrients are adequate. The micronutrients are significantly related to some of the soil properties tested, Soil clay correlated (P=0.01) positively with Cu, Zn, Mn and Fe (r= 0.476**, 0.404**, 0.407** and 0.469** respectively). Similarly, organic C correlated positively with Fe, Cu and Mn.  Also, there are significant relationships among the micronutrients; Fe correlated with all the other micronutrients – Cu, Zn, Mn (P=0.01) and B (P=0.05).  While Zn correlated with Fe, Cu and Mn. For soils of the pedons, sand and silt correlated with Zn and Cu, pH (H2O) correlated with Fe, while pH (CaCl2) correlated with B and Fe. Among the micronutrients, B and Cu correlated with Zn. There would be need for B and Zn application to the soils for successful and profitable crop production.