The effects of fertilization and manuring on the content of some nutrients in potato (var. Provita)

Abstract

The effects of fertilization and manuring on the content of some nutrients in potato (var. Provita) were studied by agronomic field experiments and chemical analysis. The different treatments included the application of 53·9 tonnes ha −1 compost manure with and without bio-dynamic sprays, 30 tonnes ha −1 raw manure alone, 15 tonnes ha −1 raw manure in combination with 228 kg ha −1 inorganic NPK fertilizer, 456 kg ha −1 inorganic NPK fertilizer alone, 908 kg ha −1 inorganic NPK fertilizer with and without 369 kg ha −1 ammonium nitrate. A control variant was left unfertilized. The potato dry matter content increased due to the application of inorganic fertilizer. There was only 1·5% increase in protein content, when ammonium nitrate was included with a higher amount of inorganic NPK fertilizer. Compost manure in comparison with raw manure was more effective for the improvement of protein content. We did not find any significant differences in the concentrations of fat, dietary fibre and crude fibre between samples treated with organic manure and inorganic fertilizer. The content of starch increased with a higher application of inorganic NPK fertilizer. The inclusion of bio-dynamic preparations and sprays with organic manure did not alter significantly the content of trace elements except zinc which was 25% lower when compared to the sample treated with organic manure and bio-dynamic preparations. Iron content was 11–45% lower in inorganically fertilized potato samples than those treated with organic manure. The content of zinc was lower in samples treated with a higher amount of inorganic NPK fertilizer. Inclusion of inorganic NPK fertilizer along with raw manure decreased the content of iron, copper and zinc. Higher application of inorganic NPK fertilizer increased the content of iron but decreased the zinc content and the concentrations of copper and manganese remained unchanged. The study indicates a complex pattern of trace element contents due to the application of different manuring and fertilization techniques.