CONTENT OF NUTRIENTS IN SOILS OF HIGHBUSH BLUEBERRY (VACCINIUM CORYMBOSUM L.) PLANTATIONS IN POLAND IN A LONG-TERM STUDY

The cultivation of highbush blueberry (Vaccinium corymbosum L.) in Poland has gained an increasing interest in the last years. Optimal fertilization of soils under highbush blueberry plantations is essential for obtaining the proper growth and yield of plants. A 12-year study (2004 - 2015) was conducted on plantations across Poland. In total, 2543 soil samples collected from the upper layer of soils (0 - 20 cm) in 220 plantations were tested. It was found that 77% of highbush blueberry plantations had a low average content of available soil nitrogen (N-NH4 + N-NO3), 68% - phosphorus, 60% - sulfur, 45% - potassium, 35 - magnesium, 7% calcium, 38% - manganese, 27% - zinc, 23% - chloride, 21% - copper and 3% - iron. Some of the soils were rich in available boron, which is unfavourable for the plants. Approximately 90% of the plantations had a low soil content of this micronutrient. A large share of soils with the high content of available calcium (52%) meant that approximately 48% of the plantations had high soil pH(H2O) (above 5.00), which is unsuitable for highbush blueberry. Around 6% of the plantations had excessively low pHH2O, but 46% presented soil reaction withing the optimal range. No serious problems due to undesirable valeus of the electrical conductivity (EC) of soils were detected. An average of 93% of the plantations had EC within an acceptable range, whereas just 7% demonstrated a high level of soil EC. The research results seem to suggest that there are good opportunities to increase the yield of highbush blueberry in terms of its quantity and quality aspects by optimizing the abundance of soils in macro-and micronutrients and maintaining the required pH(H2O) of soils.