Responses of Selected Soil Properties to Mixed Tree Plantation and Cassava Land Use in Southern Nigeria

Responses of some selected soil properties to mixed tree plantation and cassava land use in southernNigeria were evaluated in this study. The objectives were to examine variations in the selected soilproperties among the different agricultural land use types; ascertain relationships between the soilproperties; and evaluate cause-effect relationships between the soil properties. A total of 54 soil samplesat 0-15 and 15-30 cm depths were collected from mixed tree plantation, cassava land use and secondaryforest using transect sampling method. Soil samples were analysed for selected physical, chemical andbiological properties following standard laboratory methods. The results revealed significant variations(p ≤ 0.05) in the values of sand, silt, bulk density (BD), total porosity (TP), pH, total heterotrophic bacteriacounts (THB) and total heterotrophic fungi counts (THF) in soils of the three land use types. The valuesof BD and TP did not exceed the respective critical limits of 1.75 g cm-3 and 40% for productive soils.However, pH, available phosphorous (Avail. P), soil organic carbon (SOC), soil organic matter (SOM),THB and THF responded negatively to mixed tree and cassava cultivation in the 0-15 cm soil depth astheir values were lower than that of the control site. Significant positive (e.g., silt versusSOM/SOC/TN/Avail. P, and TP versus pH) and negative (e.g., clay versus SOC/SOM/Avail. P)relationships as well as significant cause and effect relationships (such as Avail. P versussilt/clay/TP/SOC/SOM/TN) were observed between some of the soil properties across the three land usetypes and soil depths. The study concluded that the examined soil quality indicators responded differentlyto the evaluated land use types.