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 southern Nigeria were evaluated in this study. The objectives were to examine variations in the selected soil properties among the different agricultural land use types; ascertain relationships between the soil properties; and evaluate cause-effect relationships between the soil properties. A total of 54 soil samples at 0-15 and 15-30 cm depths were collected from mixed tree plantation, cassava land use and secondary forest using transect sampling method. Soil samples were analysed for selected physical, chemical and biological 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 bacteria counts (THB) and total heterotrophic fungi counts (THF) in soils of the three land use types. The values of 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 as their values were lower than that of the control site. Significant positive (e.g., silt versus SOM/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 versus silt/clay/TP/SOC/SOM/TN) were observed between some of the soil properties across the three land use types and soil depths. The study concluded that the examined soil quality indicators responded differently to the evaluated land use types.