Effects of long-term differentiated fertilization on changes in the yield and chemical composition of potato tubers

Abstract

The effects of 30-years of organic, organic-mineral and mineral fertilization on the quality of potato tubers were studied in a field experiment. The fertilizers were counterbalanced each year in terms of the amount of nitrogen (manure, slurry rate I, mineral fertilizers) and organic carbon (manure, slurry rate II) introduced to the soil. Organic fertilization was supplemented with complementary PK fertilization. It was found that fertilization caused a decrease in the dry matter and starch content of potato tubers, and an increase in the yields of these components. Significantly higher yields of both components were recorded in treatments with manure and mineral fertilizers than in those with slurry, rate I and II. Vitamin C concentration was higher in potato tubers fertilized with slurry rate I and manure than in those fertilized with slurry rate II and mineral fertilizers. Total sugars accumulation was the highest in treatments with manure, whereas reducing sugars accumulation – in those with slurry rate II. PK fertilization applied with mineral fertilizers had no effect on vitamin C concentration, but caused a decrease in the content of both sugar forms. All types of fertilization contributed to an increase in total and protein nitrogen. The lowest increase in their content was noted in potatoes grown on manure, and the highest – in treatments with slurry rate II. An adverse effect of fertilization was too high concentration of nitrates (V) and an increase in endogenous amino acid content. Its highly negative influence was reported after the application of slurry rate II, as the amount of nitrogen introduced to the soil with this type of fertilizer was almost twofold higher, compared with the other fertilizers.