PROFILE DISTRIBUTION OF SELECTED SOIL PROPERTIES AS INFLUENCED BY TREE SPECIES IN MINNA, SOUTHERN GUINEA SAVANNA, NIGERIA

This study assessed the effect of tree species and soil depth on selected soil physical and
chemical properties in the arboretum of the Federal University of Technology, Minna, Nigeria.
Three mini soil profile pits were excavated under each land use type namely: teak, gmelina and
eucalyptus plantations and the arable field (control) and soil samples collected at regular depth
intervals of 0-20, 20-40 and 40-60 cm. The experimental design was 4 x 3 factorial fitted into
Randomised Complete Design (RCD) with 3 replications. A total of 36 soil samples were
collected and analysed in the laboratory following standard analytical procedures. Data were
subjected to analysis of variance (ANOVA) and means were separated using LSD (5%).
Correlation analysis was conducted to determine the relationship among soil properties. Results
indicated darker soil colour in soils under gmelina and teak than eucalyptus and the control.
Significant (P<0.05) effect of tree species on levels of sand, clay, pH, organic carbon (C), total
nitrogen (N) and available phosphorus (P) was recorded while silt and potassium (K) were not
significantly different. Soil depth affected (P<0.05) distribution of all the parameters determined
except pH and K. Sand showed significant and inverse correlation with silt (r = -0.66) and clay
(r = -0.76). Organic C had significant positive correlation with total N (r = 0.36) and available
P (r = 0.85) and negative correlation with K (r = -0.43). None of the tree species was all round
outstanding in terms of soil quality invigoration. While gmelina and teak were superior in
improving soil N and protecting soil texture and structure, eucalyptus was a promising
candidate in soil organic C replenishment. In order of priority, the study recommends
teak>gmelina>eucalyptus in afforestation for soil health improvement in Minna, Niger State.