Soils of the Degraded Derived Savanna Land in Southwest Nigeria: Distribution, Morphology and Sustainable Climate–smart Land Use Plan

Southwest Nigeria belongs to the humid tropical climate with a Wet/Dry Forest and a Derived savanna. The studied site is under the latter ecosystem (located around Ilero, 08.05N/03.22E in Kajola Local Government Area of Oyo State) and was a former mechanized farm with low-intensity land use pattern with seasonal uncontrolled burning/grazing with a subsequently degraded landscape. And to encourage the habits of sustainable land-use management, the objectives of this study were: [1] to produce a detailed soil map of an approximate 1,293ha [12.93 sq. km] land mass at the soil series level and [2] to use the soil/landform properties to formulate a land use plan suitable for a sustainable climate-smart watershed management plan. The degraded landscape is characterized by: induced drainage channels at upper physiographic positions and equally devoid of vegetation attributed to cattle grazing; surface gravels/stones/cobbles typical at the middle slope positions; iron coated surface soils on the seepage areas; and common, massive exposure of iron pans on upper slope positions. Ten mapping units identified at Soil Series level [and classified into Soil Taxonomy/World Reference Base] include Shabe (2.6%), Ogboro (9.3%), Iwaji (2.2%), Amodu (1.9%), Tede (2.7%), Iwo (18.1%), Dejo (7.0%), Gambari ( 9.6%), Shante/ Apomu soil complex ( 34.3%) and Adio soil (12.3%). Potential common limiting factors for sustainable land use/management are soil erosion, effective soil depth, stoniness, and wetness/drainage. Mixed cropping and agro-forestry are suggested viable land use options for sustainable land use/management that are a conditional factor for climate-smart agriculture and sustainable ecosystem services.