EFFECT OF SLOPE LENGTH, ASPECT AND PHOSPHOGYPSUM ON RUNOFF AND EROSION FROM STEEP SLOPES

The efficiency of phsophogypsum as an amendment for controlling erosion on embankments was studied on a Typic Rhodoxeralf soil, with 48% slope and 10 and 1.5 m long plots, with western and northern aspects and a westerly dominant wind during rainstorms. Phosphogypsum reduced the runoff by 23%, and the erosion was 2-3 times less than on the control slope. The embarkment's aspect has no effect on the amounts of rainfall and runoff, but the erosion from the long plots with a western aspect compared with the long plots with a northern aspect was 1.4 and 2.5 times higher in the control and phosphogypsum treatments, respectively. The length of the plots has no effect on the runoff, however, soil loss was 6.4 times higher in the longer plots. High correlations were found between the amount of erosion and the erosivity index or the runoff amount.