ISHS Acta Horticulturae 548: International Symposium on Growing Media and Hydroponics
ORIGINAL AND CEN-MODIFIED METHOD FOR CAT - A COMPARISON |
| Author: | P. Fischer |
| Abstract:
CAT extraction solution (Cad2 + DTPA) is used for the determination of soluble nutrients in substrates with the CEN method. According to the original method from ALT, 25 g substrate are extracted with 200 ml CAT solution (weight + volume). For the CEN-modified method 50 ml substrate are extracted with 250 ml CAT solution (volume + volume). 42 different substrate mixtures like peat substrate, peat + clay, peat + compost, residues from biogas production, and other mixtures for example peat + wood chips, were analyzed with both, the original and the CEN-modified CAT method. The correlation between the both methods depends on the nutrient analyzed. The correlation is close for N contents determined in different substrates, except for two composts and one peat-clay substrate (Fig. 1). The dispersion is higher for phosphate, indicating that the extractable P contents are dependent on the extraction ratio. Therefore the different quantity because of a different bulk density might play a role (Fig. 2). The relationship between both methods is very close for potassium. The same K contents are extracted, irrespective of the method (Fig. 3). | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
