Nitrogen Regime of the Agro-Grey Soil of a Cherry Orchard and the Yield of Trees when Applying Fertilizers

Abstract

2018–2022 in order to estimate the nitrogen dozes essential for this fruit crop in the first decade after planting. The field experiment was carried out at an orchard located in the forest-steppe zone of the Central Russian upland (Orel region). Urea and potassium sulfate were applied to the soil once a year in early spring with doses arising from N30K40 to N120K160 kg/ha. The dynamics of N-NH4 in the soil of fertilized and unfertilized plots were similar, the lowest level of the indicator was in July during fruit ripening. The content of N-NO3 in unfertilized soil fluctuated slightly through the vegetation period. The fertilizer treatments led to more intensive seasonal fluctuations of N-NO3 in dependence of weather conditions. Annual fertilization led to annual increase of N-NH4 content by 2–12 and N-NO3 by 18–70 times, depending on the dose of nitrogen. But the accumulation of mineral nitrogen in root zone over the years was not revealed. The fertilizers did not affect sour cherry yield when it was lower than 15 t/ha. Still in the high-yielding season the fertilizers application in dose of N60K80 was necessary to reach the yield 20 t/ha.