Soil Quality Assessment for Sustainable Land Use and Management

Tropical soils are generally fragile and hence highly degraded due to such factors as low organic matter content, dominance of low activity clay, high susceptibility to erosion etc. Coupled with this, there is population pressure on the limited land and this has become a great challenge for land management and agricultural production. It is therefore imperative to adopt science-based and efficient approach for monitoring the impact of land use on land resources. This study has assessed soil quality under two land use types to establish the effect of land use on soil quality and demonstrate the kind of assessment necessary to arrest land degradation before it progresses too far. It was conducted within Oluyole Local Government Area in Oyo State, Southwestern Nigeria under two agricultural land use types (cacao and maize). For each of the two land uses, two farmlands were chosen for the study. In each of the farmlands, five sampling points were located and soil samples were collected at 0 – 15 cm and 15 – 30 cm depths. The samples were processed and analyzed for selected indicators, following standard methods. Soil quality was assessed using Soil Management Assessment Framework. Sustainability assessment was carried out on a scale of < 20 (highly sustainable) to > 40 (not sustainable) - i.e. ‘less is better’. The relationship between soil quality and sustainability was established using regression analysis. Soil quality index was 85 – 87% under cacao and 60 – 77% under maize. Sustainability index ranged from 14 – 19 (highly sustainable) under cacao to 25 – 28 (moderately sustainable) under maize. High positive linear relationship (R2 = 0.86 and 0.94) was obtained between soil quality and sustainability. The results thus indicate that the land use and management systems in the farms studied are sustainable, although the arable land use requires closer monitoring.