EFFECTS OF FREEZING ON RHIZOSPHERE AND ROOT NUTRIENT CONTENT USING 2 SOIL SAMPLING METHODS

This study investigated how deep freezing affects the mineral nutrient content of roots and rhizosphere soil. Two different methods of separating the rhizosphere from the roots were used: i) a brushing method, where the rhizosphere soil was brushed off and ii) a washing method, where the rhizosphere was extracted together with the roots. When unfrozen material was used, the concentrations of K and Fe were significantly higher in the washing method as compared with the brushing method. When the material had been deep frozen, significantly higher concentrations of K, Fe, Mg, and Al were found in the extract from the washing method, indicating a considerable leakage from the roots. No significant differences were found between frozen and unfrozen material with the brushing method. In bulk soil, freezing resulted in increased concentrations of Mn, Al and Fe, even when no roots were present. The brushing method can be used for both frozen and fresh material, although fresh material is preferable. Extraction of soil plus roots cannot be recommended for deep frozen soil.