Effect of Dolomite and 'Photomag' on Nutrient Status of Lowbush Blueberry

Abstract

Two commercial lowbush blueberry fields in Washington county were used in this study. At Brook Lot, 1.5-m × 46-m treatment plots received fluid dolomite (1670 kg·ha-1) or combinations of dolomite and PHOTOMAG at 5, 10, or 15 kg MgO/ha as foliar sprays when plants reached three-quarters full growth in late June 1996. At Pike Brook, 1.5-m × 23-m treatment plots received the same treatments plus a 10 kg MgO/ha only treatment. Nontreated plots served as controls in a randomized complete-block design with eight replications at each location. At Brook Lot, leaf Mg concentrations were raised by all treatments compared to the control. At Pike Brook, PHOTOMAG alone showed little effect on soil pH and soil Mg concentration and was ineffective in raising leaf Mg concentrations in combination with dolomite to higher levels than dolomite alone, except at the highest rate (15 MgO). Although leaf Mg concentrations were raised, no measurable changes in plant growth characteristics, potential yield, or harvestable yield were found. Applying dolomite and/or PHOTOMAG to a field deficient in Mg might have resulted in different results.