Norwegian Journal of Agricultural Sciences : nutrient concentrations in the liquid phase of growth substrates
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Samples of the liquid phase of growth substrates at container capacity were obtained using a dilution technique, and a chemical analysis was carried out. The measured concentrations were combined with the physical characteristics of the growth substrates to calculate nutrient concentrations immediately before the nutrient solution was re-added. The results of two laboratory studies indicated high and fluctuating nutrient concentrations close to the levels regarded as lethal for Norway spruce. Differences in element concentrations between the growth substrate liquid phase and the nutrient solution were discussed in terms of a disparity between the water and nutrient uptakes of the seedlings. Periodic heavy leaching with water did not bring the concentrations in the liquid phase to the same level as concentrations in the added nutrient solution. The high concentration of nutrients in the substrates were supported by foliar analysis. Even seedlings grown with deionized water for 56 days after the last addition of nutrient solution grew just as well as the fertilized ones. However, malnutrition was obvious from foliar analysis.
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