FIELD MEASUREMENT OF FACTORS RESPONSIBLE FOR SOIL EROSION IN TROPICAL NIGERIA

Résumé

The soil erosion factor K, is the quantitative expression of inherent successof a particular soil to erode at different rates when the other factors that affect soil erosion are standardized. This study was carried out based on a completely randomized design to determine the erodibility of three different plots under two management conditions (one left bare of vegetation, and the other planted with Grain Amaranth). Runoff and soil loss measurements were measured after every rainstorm. Results revealed that measured K on the vegetable plots does not indicate much variation on the three plots, but were slightly lower than measured K on the bare plots.
Plot 1 recorded the least erodibility (0.0424 for the vegetable plot and 0.0549 for the bare plot), while plot 3 had the highest with (0.0492 for the vegetable plot and 0.0684 for the bare plot respectively). The percentage sand content on all runoff plots decreased slightly after the experiment was concluded. So also was the organic matter content. Examination of chemical properties of the soil before and after the studies revealed that the top soil of the runoff plots showed lower organic carbon content, available Nitrogen and Phosphorus content, the exchangeable Potassium on all the runoff plots were lower after soil erosion, the same thing for Magnesium
and Calcium.Plot 3 recorded the highest runoff and soil loss and hence the highest erodibility these may be attributed to its higher slope steepness of 3% when compared to those of plots 1and 2 which has slope steepness of 2% each