Assessment of Soil Degradation under Agricultural Land Use Sites: Emerging Evidence from the Savanna Region of North Eastern Nigeria

Soil degradation remains a global environmental phenomenon that is interpreted differently in different environments, despite its global dimension in terms of loss of soil fertility from crop fields in most of the major agricultural regions of the word. This study reports the results of a quantitative index (indices) developed to assess soil degradation associated with agricultural land uses for two contrasting topographies. The study also, identifies the basic underlying pattern of the interrelationship between the soil properties in a part of the Northern Guinea Savanna belt of Nigeria. Using thirteen soil properties, three indices are developed namely: organic nutrients, cation exchange capacity, and soil texture. The indices range from 34.3 % for Ca and 33.7 % for CEC for fallow land to 68.8 % for Na and 57.8 % for OC for continuously cultivated farms on hillslope and flatland sites, respectively. The organic nutrients index was the most degraded index in both sites. The results of the analysis of factor scores for the three land Use types on both sites show two to three basic underlying relationships among the soil properties analyzed, with continuously cultivated farms being the worst degraded then fallow plots with forest fields being the least degraded. The study recommends that the agricultural quality of the soil be evaluated by monitoring only these few soil properties in the study region.