Dry matter yield of potato tubers was significantly modified by the intercrop fertilization, straw fertilization and their interaction (table 5). The highest dry matter yield of potato tubers was collected from the object fertilized with a mixture of white clover with Italian ryegrass, white clover and phacelia used in the form of mulch. Dry matter yield of potato tubers fertilized with phacelia did not differ significantly from the yield recorded on the farmyard manure. Only after the application of Italian ryegrass dry matter yield of potato tubers was significantly lower than that recorded on the farmyard manure. However, in this case, dry matter yield was significantly higher than that obtained on control object, without intercrop fertilization. Straw fertilization also significantly differentiate dry matter yield of potato tubers. On objects with straw dry matter yield of potato tubers was greater than on the objects without straw. There has been an interaction, which shows that the highest dry

matter yield of potato tubers were obtained from the object fertilized with a mixture of white clover with Italian ryegrass in combinations without straw and with straw, white clover in combination with straw, and phacelia used in the form of mulch and also in combination with straw, and the smallest on control object, without intercrop fertilization.

2.1.3 Starch content in potato tubers

Statistical analysis showed a significant effect of examined factors and their interaction on starch content in potato tubers (table 6). Intercrops fertilization of potato, with the exception

of white clover caused a significant increase of starch content in potato tubers in comparison with farmyard manure fertilization. The starch content in potato tubers fertilized with white clover did not differ significantly from that observed in potato tubers fertilized with farmyard manure. However, on control object starch concentration in potato tubers was significantly lower than in tubers fertilized with farmyard manure. An interaction has been noted, which shows that the highest concentration of starch was noted in potato tubers fertilized with phacelia both plowed down in the autumn, and left till spring in the form of mulch in combination without straw and with straw and Italian ryegrass in combination with straw, and the lowest in potato tubers cultivated on control object.