Effects of soil type and soil treatment on solubilization of 13 elements in the root zone and their absorption by blueberry bushes

In blueberry culture, sulfur is applied to enhance soil acidification, and fertilizer is applied to increase growth and yield. We investigated the effects of soil management on the solubilization of 13 elements in the root zone and their relationships with absorption by blueberry bushes. In a 2-year pot experiment, four-year-old rabbiteye blueberries 'Onslow' were grown in one of three soils (an Andosol, a Cambisol, or a Fluvisol), with or without soil treatment (no treatment, acidification, fertilization, or acidification plus fertilization). The soil solution was collected eight times during the experiment. Fruit, leaves, branches, stems, and roots were sampled during and at the end of the experiment. The concentrations of 13 elements (N, Na, Mg, Al, P, K, Ca, Mn, Fe, Cu, Zn, Rb, and Cs) in the samples were analyzed. Soil solution pH was also measured. In all soils, the soil solution pH was decreased to 3.7-4.3 by acidification and also to 4.5-6.1 by fertilization. Acidification tended to increase the average concentrations of Al (77-1421 fold), Zn (18-414 fold), and Fe (1.2-204 fold) in the soil solution, whereas fertilization tended to increase the average concentrations of NH4sup(+) (33-205 fold), Cs (3.0-9.9 fold), and NO3sup(-) (2.1-8.4 fold). The acidification plus fertilization further increased the concentrations of these elements in the soil solution except for Fe. On the other hand, the concentrations of Na, P, Fe, and Cu in the soil solution were influenced by the soil type and were not changed by any soil treatments in a particular soil. Across all soil types and treatments, the average concentrations of N, P, K, Mn, Cu, and Zn in the soil solution were significantly correlated with the content of the corresponding element in the blueberry bushes. For these elements, nondestructive sampling and analyses of soil solution in the root zone can be effective as a real-time soil test. The content of seven other elements (Na, Mg, Al, Ca, Fe, Rb, and Cs) in the bushes did not reflect the soil solution concentrations partly due to the lower requirement than their supply from the soil.