ASSESSING EVIDENCE FOR SOIL DEGRADATION IN THE SEMI-ARID RANGELAND OF YOBE STATE, NIGERIA.

This paper examines soil chemical degradation in one of the largest statutory grazing reserves in Yobe State, Nigeria (The Jakusko-Nasari grazing reserve). Soil samples were collected and analysed using standard Held and laboratory techniques. To compute the indices of soil degradation, the mean value for each soil parameter used in the grazed plots (the heavily grazed, moderately grazed and light grazed sites) is expressed as a percentage of the mean value in the Savanna woodland site (the reference location); and the value obtained is subtracted from 100. The results reveal an enrichment of organic matter, total nitrogen, available phosphorus and other soil nutrients in the heavily grazed sites close to the water points. This suggests a net transport of nutrients from the outlying areas inwards towards the water points! In spite of this pattern, the nutrient status of the soil is significantly lower than those of Southern Guinea Savanna, it was recommended that the rangeland he reseeded with promising legumes such as Slylosanthes species and Alylosia Scarabaciodcs in order to help fix nitrogen, thus increase soil nutrient; improve soil structure and increase ovcrallTangc productivity.