EXTRACTION TECHNIQUES, AND CHEMICAL ANALYSES IN GROWING SUBSTRATES¹ (DANISH CURRENT AND PROSPECTIVE METHODS).

The traditional and authorized methods of extraction and analysis of growing substrates, are based on methods developed for mineral soils. Soil analyses are based on weight-samples (20 g), and the results are expressed as -figures (-tal). Otherwise for the substrate analyses, which are based on volumen-samples (20 ml), and the results are expressed as -values (-værdier).

Before apportion and extraction, the substrate samples are dried (50–60°C), cruched and sieved (2 mm). The extraction time is 1 hour. Extraction solutions and methods of chemical determinations are as follows:

Searched chem. parameter

Extr. solution

Meth. of chemical determination:

pH, EC	Water	Electrodes
NO3-	o,02 M acetic acid	Ion selective electrode
P	"	Spectrophotometry
K	"	Flame photometry
Mg	1 M ammoniumchloride	Atomic absorption spectr.
B	Morgan solution	Carmine-red (spectr.)

Values are not defined for other nutrients.

The results from the described methods are rather empirical in relation to the real chemical condition in the substrate -water-plant system.

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