Nitrogen, as one of the most important elements in the life of a plant, has a significant impact on the growth and bearing of apple trees. The natural amount of nitrogen in soil is essential in the process of fertilization with this component. The experiment was established in 2000 at an experimental orchard of the Department of Pomology, Warsaw University of Life Science in Wilanów, on apple trees of the cultivar Jonagored. The aim of the study was to evaluate the needs for apple orchard fertilization with nitrogen that would minimize the use of nitrogen fertilizers while maintaining an optimal content of available nutrients in the soil, leaves and fruits of apple trees. There were four different treatments with nitrogen:  N-0 (no nitrogen); N-50 (50 kg N ha-1 over the whole growing area in early spring); N-100 (100 kg N ha-1 over the whole growing area in early spring); and N-100sward (100 kg N ha-1 in early spring only in sward alleyways). The studies were conducted in 2010 and 2013 (content of selected minerals in the soil) and from 2010 to 2012 (nutrient content in leaves and fruits). Application of nitrogen did not affect soil pH, content of available potassium, phosphorus and magnesium or the ratio K/Mg in the soil. In the analyzed period, there were no differences in the content of N, K, Mg, P and Ca in the fruits. Nitrogen fertilization caused an increase in the content of N in leaves when compared to the unfertilized combination. The opposite situation was observed in the case of phosphorus in leaves.

22.1.2017