Estimation of Water Erosion of a Nigerian Guinea Savanna Soil
The possibility of establishing an equation for estimating soil loss in Samaru – Zaria environment was investigated using measured values and two erosion computer models. Three experimental plots were established namely: bare soil, vegetated soil and cultivated soil to measure soil detachment, soil loss and runoff on a storm by storm basis at Ahmadu Bello University farm, Shika – Samaru during the 3 years of study. Soil detachment losses were measured by collecting all splash losses in a 25mm x 31mm hollow rectangular plastic container buried in the soil in a grid pattern to catch soil splash at a maximum of one meter radius. Similarly, both runoff and soil loss were also collected inside a drum buried at the end of each plot. The results indicate high erosion rate of 2.62 kg/m2/yr was measured for bare soil on 5.8% slope while 1.15 kg/m2/yr was recorded as mean erosion rate for vegetated plot on 6.6% slope. Slight over prediction of tested model was experienced. However, the European Soil Erosion Model (EUROSEM) is recommended for erosion prediction for bare and vegetated soil in Samaru – Zaria environment, while the Water Erosion Prediction Project Model (WEPP) is recommended for further experimentation in the southern part of Nigeria where a substantial amount of rainfall per single storm normally occurs. The study concludes with emphasis on using a soil conservation planning guide of 2.7 kg/m2/yr erosion rate in Samaru – Zaria, Northern Guinea Savanna zone of Nigeria.