APPLE TREE REACTION AT DIFFERENT AGE PERIODS OF RE-CULTIVATION ON CHANGES IN THE SOIL NUTRITIVE REGIME UNDER LONG-TERM FERTILIZATION

In order the intensive orchards bear fruit stably and give high yields every year, the mineral nutrition of fruit trees must be balanced with the help of fertilization. The soil fertilization plays an important role in this process, which provides the optimal content of essential mineral elements for fruit trees in optimal quantities. The soil nutritive regime and, accordingly, the yield of apple orchards in such conditions are significantly increased. The results of studies of soil nutritive regime and yield of apple trees of Calville snow variety on the seedling rootstock and Idared variety on the seedling and vegetative M4 rootstocks under re-cultivation on mineral nutrition backgrounds, created by long-term (over 86 years) application of different fertilizer systems on the dark-gray podzolized soil. Long-term systematic application of organic and mineral fertilizers and their combination provided the nitrate nitrogen content in the soil in the range of 26.2-28.6 mg/kg, mobile compounds and forms of phosphorus and potassium – 207-236 and 261-270 mg/kg of soil respectively, which exceeded the optimal levels of their quantity in the dark gray podzolized soil. Such changes in the apple trees supply with the main macronutrients, in particular against the background of systematic long-term application of organic and organic and mineral fertilizers, contributed to an increase in the total yield of experimental varieties by 17-35%. In the first period of growth and fruiting of young apple trees were mostly used for the formation of biomass of nitrogen vegetative organs for the plant fertilization, and in the period of full fruiting of potassium to create a fruit harvest. Increasing the Р2О5 content was ineffective. The higher efficiency of the organic fertilizer system was due to a greater increase in the mineral nitrogen content in the soil, and, especially, movable forms of potassium and a better improvement of physical and biological characteristics of soil fertility, as established by the studies of long-term use. It was found that under the organic fertilizer application the soil is enriched not only with N, P and K, but also with trace elements of mineral nutrition of plants