The effect of urea and urea with urease inhibitor on the content of macronutrients in tubers and tops of potatoes (Solanum tuberosum l.)

Abstract

In two-year small-plot field experiments in Žabčice u Brna we explored the effect of nitrogen fertilisation with urea and urea with urease inhibitor (Urea + UI) on the content of macronutrients (N, P, K, Ca, Mg) in tubers and tops of potatoes of the variety Karin. The experiment involved 7 treatments. Nitrogen rates in treatments 1-7 were the following: 1) 90 kg N/ha - Urea; 2) 72 kg N/ha - Urea; 3) 54 kg N/ha - Urea; 4) 90 kg N/ha - Urea + UI; 5) 72 kg N/ha - Urea + UI; 6) 54 kg N/ha - Urea + UI; 7) unfertilised control. Each treatment was repeated 4 times. Both fertilisers (Urea, Urea + UI) were refl ected irregularly in the contents of N, P, K, Ca, Mg in the potato biomass and were based on the weather of the year, rate of fertiliser and analysed plant organ (tuber, top). In both years the contents of N, K, Ca and Mg were higher in the tops. The P content was balanced both in the tops and tubers. Some changes in the chemical composition were observed particularly in the case of nitrogen. In 2010 the nitrogen content was higher in tubers (1.44-1.65% N) after the application of both of the higher rates of urea + UI than after the application of urea alone (1.30-1.34% N). In 2011 the N content in tops decreased to 2.97-3.26% N when the highest rate of N was applied in both fertilisers, as against the other treatments (3.60-4.09% N). The contents of the other elements (P, K, Ca, Mg) were not significantly aff ected by the kind fertiliser and way of fertilising or the diff erences among treatments were minimal. In general we can conclude that er the application of both types of fertilisers the contents of the observed elements did not change fundamentally in the tops or tubers.