The aim of this investigation was to determine balance of nitrogen, phosphorus and potassium in organic crop rotation system on light soil. The crop rotation comprised following agricultural plant species: potato, oat, yellow lupine, rye, phacelia. Apart from these main species 3 plants were cultivated as intercrop: field pea, white mustard, serradella. Before potato cultivation the manure in dose of 25 t.ha -1 was applied. The calculations were based on real data of obtained yields and nutrients content in the yields. The "on surface of field" method was used in this investigation. In the crop rotation positive balance of nitrogen (+20,4 kg N.ha -1 per year -1) and slightly negative one for phosphorus (-3,1 kg P.ha -1 per year -1) and potassium (-4,5 kg K.ha -1 per year -1) were noted.
