EVALUATION OF THE MINERAL NITROGEN DYNAMICS IN AGRO-GRAY SOIL UNDER SEED AND STONE FRUIT ORCHARDS

Abstract

The aim of the investigation was clarification of specific features of fruit crops nitrogen nutrition which may be useful for elaboration the precision nutritional management for specific crops. The seasonal dynamics of mineral nitrogen (ammonium + nitrates) was studied in field experiments in 2018 and 2019 growing seasons. The investigations were carried out in medium-sized apple and sour cherry orchards located in the orchard area of the Russian Research Institute of Fruit Crop Breeding (Oryol Region). The soils of experimental orchards are loamy Haplic Luvisols with neutral reaction high content of available phosphorus. Fertilizers at doses increasing from N30K40 to N120K160 were applied annually in early spring. Fertilization of orchards contributed to an increase in mineral nitrogen content by 1.5 – 5.0 times, depending on the dose. The nitrogen dynamics in the soil of fertilized and unfertilized plots was similar and the biological features of the crops affected on the soil nitrogen regime. The lowest indicator's level in the soil under sour cherry was in July during fruit ripening, while in the apple orchard a low nitrogen content was noted in August. Studies have shown that in the climatic conditions of the Central Russian Uplands, loamy haplic Luvisols without additional application of nitrogen fertilizers can provide a favorable level of nitrogen nutrition for apple and sour cherry trees in the first years of fruiting.