EFFECT OF THE FLOOR MAINTEMENT SYSTEMS ON THE CONTENT OF PHOSPHORUS IN THE SOIL AND CHERRY TREES

The study was carried out in an experimental sweet cherry plantation, established in the spring of 1991 at the Institute of Agriculture - Kyustendil, Bulgaria on Chromic Luvisols (LVch), heavy loamy soil. It was found that with the application of considerable amounts of phosphorous and potassium (1200 kg/ha Р2О5 and 1000 kg/ha К2О) with the pre-planting mineral fertilization was provided a moderate supply of the soil, up to the fourth year after planting. Afterwards soil phosphorous balance was with a negative value. With the green manuring after the rye-peas mixture growing, for the period of investigation 9.8-10.5 kg/m2 fresh plant matter was incorporated in the soil, containing 0.84-0.88%  Р2О5. Significantly higher quantity plant matter – about 28.5 kg/m2 was removed by the interrows crops and the phosphorous content was from 0.75 to 0.78% of the dry matter content. As a whole, average for the experimental period less supplied with phosphorous were the leaves of the cultivar Bing at the lower nitrogen (N100) fertilizer norm. This was most strongly manifested in the permanent fallow.