Impact of Land Use System on Soil Quality in Southwest Nigeria

A soil quality (SQ) evaluation was conducted on three different farm locations in the Ijebu-Igbo region of Ogun State Nigeria to ascertain the health status of the soils. The farmlands have been subjected to different land use systems (LUS) for over ten years including plantain/banana orchard, arable farming and fallow/secondary forest. Soil samples were obtained at 0-30 cm and 30-60 cm depths from each farmland. The SQ of the farms was evaluated quantitatively using the SQ index equation proposed by Bajracharya et al. (2006). The results revealed that at 0-30cm depth, the LUS had significant (P<0.05) impact on the SQ indicators with the fallow land recording the highest pH (6.69), zinc (6.12 mg/kg) and ECEC (14.95 cmol/kg) while, high significant (P<0.01) impact was observed on iron with the fallow land recording 21.21mg/kg. At 30-60cm depth, the LUS had high significant (P<0.01) impacts on the SQ indicators with plantain/banana field recording the highest organic carbon (0.79 g/kg) and total N (0.09 g/kg) while the fallow land had the highest pH (6.65), ECEC (13.72 cmol/kg) and iron (31.66 mg/kg). The LUS had no significant (P<0.05) impact on the SQ though the fallow/secondary forest had the highest SQ level (0.56) and plantain/banana field the least (0.52). The results also showed that the land use systems didn’t have any significant impact on SQ at both soil depths though the upper soil layer had better mean soil quality (0.54) than the lower layer (0.48). Soil quality declined with depth in the study sites