Statistical analysis showed a significant effect of examined factors in experience on the starch yield of potato tubers (table 7). Intercrop fertilization caused a significant increase of starch yield in comparison with starch yield of potato tubers from the control object. The highest starch yield was obtained from the object fertilized with a mixture of white clover with Italian ryegrass, white clover, phacelia plowed down in autumn and left till spring in the form of mulch. Only after the application of Italian ryegrass the starch yield of potato tubers fertilized with Italian ryegrass was significantly lower than that recorded in the farmyard manure. Straw fertilization also modified the starch yield. At the sub-block with straw starch yield of potato tubers was significantly higher than at the sub-block without straw. An interaction has been shown that intercrop fertilization with straw fertilization, which shows that the highest yield of starch was obtained from the object fertilized with a mixture of white clover with Italian ryegrass and phacelia used in the form of mulch in combination with straw, and the smallest from control object, without intercrop fertilization.

potato tubers harvested from control object. The highest concentration of reducing sugars noted in potato tubers harvested from control object. Intercrop fertilization significantly decreased reducing sugars content in potato tubers in comparison with their concentrations recorded in potatoes tubers harvested from control object. Indeed, the lowest content of reducing sugars was noted in potato tubers fertilized with phacelia both plowed down in the autumn, and left till spring in the form of mulch. Straw fertilization also significantly differentiate the concentration of reducing sugars in potato tubers. Higher its content was noted in potato tubers in the sub-block without straw than on the sub-block with straw.