APPLE TREES FERTILIZATION AND ITS INFLUENCE ON THE POTASSIUM CONTENT IN SOIL AND PLANTS IN CORRELATION WITH CALCIUM AND MAGNESIUM ABSORTION

The paper presents how the soil fertilization with NPK in different doses and combined with two types of foliar fertilizers, applied to an apple tree orchard, changes the potassium content in soil and leaves. For a better understanding of the results, chemical analysis of the leaves and of the soil at two depths: 0-20cm and 20-40cm were chemically performed. The study was carried out in an apple orchard, located in the Didactic Farm "V. Adamachi" that belongs to the University of Life Sciences from Iasi (IULS), Romania. Results shows that fertilizers applied in the soil had a positive influence, increasing the soil content of potassium closer to the optimal range: 200-300 ppm. However, the content of potassium in the apple tree leaves stays low and below the optimum condition. The control (no fertilizers applied) had the lowest content for Kt (0.99%) in the leaves. Studying the content of calcium (mean - 1.65%) and magnesium (mean -0.74%) in the dry matter of the leaves we see that there are not significant differences between the fertilization variants. Their values exceed the optimal limits.