In this paper, it is presented the impact of varying amounts of sown oats’ seeds cultivated with and without supplementary crops, as well as of the oats’ field location on a slope on the productivity and soils protecting features of oats. It was stated that water erosion occurring on oats’ site with supplementary crops caused lower rates of crop yield (0.31-0.34 t/ha) and 11-21% higher soil losses. The slope grade increased by 5% resulted in lower crop yielding by 0.21 t/ha and in 40% higher soil losses.