Statistical analysis showed a significant effect of examined factors and their interaction on total protein content in potato tubers (table 11). Intercrop fertilization significantly increased the concentration of total protein in potato tubers in relation to its content recorded in potatoes harvested from control object. Indeed, the highest concentration of total protein were characterized by potato tubers fertilized with white clover and with phacelia both plowed down in the autumn and left till spring in the form of mulch. The content of total protein in potato tubers fertilized with a mixture of white clover with Italian ryegrass did not differ significantly from that observed in potato tubers fertilized with farmyard manure. However, fertilization of potato with Italian ryegrass caused a significant decrease in total protein content in potato tubers in comparison with farmyard manure fertilization. Straw fertilization also significantly modified the concentration of total protein in potato tubers. On objects with straw total protein content in potato tubers was significantly higher on objects without straw. An interaction has been noted, which shows that the highest concentration of total protein was characterized by a potato fertilized with white clover, white clover with straw, and phacelia both plowed down in the autumn, and left till spring in the form of mulch, in combination, without straw and with straw, whereas the lowest potato tubers collected from the control object without intercrop fertilization.