The impact of soil nutritional conditions on sour cherry yield and seasonal dynamics of mineral nitrogen in root zone

The research aimed to study seasonal dynamics of content of Nmin (ammonium and nitrate forms of nitrogen) in the soil of a young sour cherry orchard as a ected by nitrogen fertilizers. The experiment was conducted with 4-years old sour cherry trees of the ‘Turgenevka’ variety during the growing seasons of 2018 and 2019. The experimental orchard was situated at forest-steppe zone of the Central Russian Upland (Orel region) with loamy Haplic Luvisol. The treatments included: 1. Control (without fertilizers); 2. N30K40; 3. N60K80; 4. N90K120; 5. N120K160. Urea and potassium sulfate were used as fertilizers and were soil applied once a year at early spring. Soil samples were collected in soil layers from a depth of 0…20, 20…40 and 40…60 cm ve times during the growing seasons: in May, June, July, August and September. Without fertilizers, mineral nitrogen content varied within 3.1…31.7 mg/kg during both growing seasons. The fertilizer treatments resulted in essential rise of Nmin to 4.7…147.6 and 20.3…102.5 mg/kg in 2018 and 2019 growing seasons respectively. In both 2018 and 2019 the Nmin concentration in 0…60 cm soil layer was the highest in May…June, and decreased by 1.3-5 times in July…August. The fertilization by urea in N90 and N120 doses led to at essential increase of soil nitrogen content by 1.6-5 times compared with unfertilized soil in early summer. The movement of mineral nitrogen to the deeper soil layers was observed when applying of nitrogen fertilizers at the dose of N120. The greatest productivity of 4-years old ‘Turgenevka’ sour cherry trees was observed at N120K160 treatment (5.38 and 9.33 kg/tree in 2018 and 2019 respectively), but the increase in yield compared to the control was not statistically signi cant.