This paper presents results of an experiment carried out in 2000-2003 in the mountain region (southern Poland, 545 m a.s.l.) to determine the effect of over-ground parts growth of fodder beet, winter triticale and horse bean on the intensity of soil losses. The research was conducted on the hillside with a 16% slope with the simulated rainfall (105 mm; 1.75 mm/min) applied at seven developmental stages of the plants. It was stated that soil protective efficiency of the fodder beet, horse bean and winter triticale started at about 60, 30 and 15% of covering the soil surface, respectively. The influence of over-ground parts of the plants (x) on the soil erosion (y) can describe the following regression equations: for fodder beet: y = -9.37x + 29.4 (R2 = 0.677; n = 82); for horse bean: y = -8.44x + 26.41 (R2 = 0.698; n = 96); for winter triticale: y = -4.98x + 15.61 (R2 = 0.66; n = 112). The obtained results made possible verification of the nomograms determining the value of the C indicator (cropping factor, i.e. index of soil coverage and cultivation calculated as a ratio of soil mass eroded from the field covered with specific crop to mass of soil eroded from black fallow with a 9% slope angle) present in USLE equation (Universal Soil Losses Equation, method commonly recommended by FAO for studies on erosion) for tested plants under similar conditions.