Effect of nutrient supply from different sources on some quality parameters of potato tubers

Application of mineral fertilisers, especially nitrogen ones, increases potato yields. On the other hand, it can depreciate the quality of potato tubers and raise storage loss. With bio-fertilisers like UGmax, farmers can limit the need for mineral fertilisers by activating minerals which occur in soil. Microorganisms contained in UGmax, enriched with the start-nutrition medium, process (compost) residue of the last harvested crop, straw, manure break crops (organic fertilisers), etc. Together with soil minerals, they make humus, a natural environment for soil life as well as a ‘store’ of nutrients. The aim of the following, 3-year research was to determine changes in the content of vitamin C, nitrogen, phosphorus, potassium and crude protein (nitrogen x 6.25) in cv. Satina potato tubers stored for 6 months indoors at the temperature of 4°C, depending on previous application of soil fertiliser (with/ without UGmax), varied organic matter (without fertiliser, stubble intercrop: pea, straw and farmyard manure (FYM) as well as a half dose of mineral fertilisation as compared with the control. The highest vitamin C content was recorded in potato tubers from the treatments with FYM, full NPK and soil fertiliser. With half the dose of mineral fertilisation, UGmax most effectively increased the vitamin C content in potato tubers in the treatments with FYM and pea. The biggest decrease in the content of that nutrient after 6-month storage appeared in tubers from the plots with FYM, 50% NPK and without UGmax (38.5%). The content of nitrogen, phosphorus, potassium and total protein in tubers significantly depended on the dose of mineral fertilisation, where full NPK increased the content of the analysed nutrients. Moreover, the content of potassium was significantly higher in tubers from the plots with farmyard manure (FYM). The use of the soil fertiliser significantly increased nitrogen and total protein in tubers. After 6-month storage in chambers at + 4°C, the nitrogen, phosphorus and potassium content decreased slightly, on average by 4.9%, 12.4%, 13.1%, respectively.