02169naa a2200217 a 450000100080000000500110000800800410001910000170006024500920007726000090016930000150017852015410019365000160173465000180175065000120176865000110178065300130179165300100180465300120181477301250182613275992002-11-22       1977    bl uuuu     u00u1 u    #d1 aROOSE, E. J.  aApplication of the universal soil loss equation of wischmeier and smith in west Africa.  c1977  ap. 177-187  aBased on more than 400 plot-year data from erosion plots of nine stations in five West African countries, a critique is made of the Universal Soil Loss Equation in relation to its use in West Africa. Preliminary results from this region suggest that there exists a simple approximate relationship between the annual climatic erosion index R (EI 30) and the mean annual rainfall (H), namely R =1/2H, making it possible to extrapolate the results to compute R. The erosivity increases from the Sahel (R = 100) to the most humid tropical zones, where extremely high values are encountered (R = 1000 to 2000). The vegetal cover is the most important factor in preventing runoff and erosion, regardless of climatic aggressivity, the slope and the soil type. However, culturaltechniques can significantly influence the erosion when the soil is partly covered. The resistance of the soil can be approximately evaluated using the nomograph of Wischmeier, with appropriate adjustment for the gravel contents of the soils, but further evaluation of the topography factors (L and S) is needed. Erosion control techniques (P) involving terracing are both expensive and less efficient than biological control methods, which establish and maintain a vegetal cover by thick and early sowing, correct cultivations, adequate and balanced fertilization, mulching with straw, use of rotations, and buffer strips. Although the Wischmeier equation enables the factors determining erosion in territories in West Africa to be defined, its is not universal ...  aAgricultura  aConservação  aErosão  aManejo  aControle  aSolos  aTropico  tIn: GREENLAND, D.J.; LAL, R. Soil conservation and management in the humid tropics. Chichester: John Wiley & Sons, 1977.