ANALYSIS OF SUBSTRATES BY NAHCO3-DTPA METHOD
Progress in substrate analysis should take into consideration that extraction solution has to measure plant availability of nutrients as exactly as possible and that as many elements as possible should be determined in the same extract. Based on proposals of Soltanpour et al. (1977) an extraction solution consisting of 0,5 M NaHCO3 + 0,005 M DTPA was developed. Pot trials were carried out with different substrates, different pH-values, different sources and amounts of phosphorus and different copper levels. With Chrysanthemum as test plant the new method let to a better relation between P-content of substrate and yield, compared with a traditional acid extraction method. The main advantage of the new method is avoiding overestimation of P- content in substrates with high pH and in substrates fertilized with less soluble phosphates. The method is also suited to separate Cu deficiency from normal contents. Therefore the NaHCO3-DTPA method has the potential to measure macro- and trace elements in the same extract.
Alt, D., Gizewski, V.T. and Schroer, B. (1988). ANALYSIS OF SUBSTRATES BY NAHCO3-DTPA METHOD. Acta Hortic. 221, 395-402