EFFECT OF MANY-YEAR NATURAL AND MINERAL FERTILIZATION ON YIELDING AND THE CONTENT OF NITRATES (V) IN POTATO TUBERS

The present research, carried out based on many-year long-term experiment, aimed at determining yielding, the content of total protein and the content of nitrates (V) in potato tubers as a result of the fertilization applied. There were observed significantly lower tuber yields whenever mineral fertilization only was applied. The varied nitrogen fertilization and combined fertilization with nitrogen and manure significantly modified ‘Bila ’ potato tuber yielding. Significantly highest yield, as much as 49.5 % higher, as compared with the control, was recorded after the application of nitrogen at the dose of 180 kg N·ha–1 with manure. The content of total protein in ‘Bila ’ potato tubers ranged from 94 g·kg-1 to109 g·kg-1 and it was significantly determined by the fertilization used. The content of nitrates (V) was determined by the fertilization applied and ranged from 133 to 222 mg·kg-1