METHODS USED AT WEST OF SCOTLAND AGRICULTURAL COLLEGE FOR ANALYSES OF LOAMLESS COMPOSTS AND RECOMMENDED LEVELS FOR TOMATOES GROWN UNDER GLASS

Analyses of loamless composts is carried out on three extracts at a 1:2 volume to volume, sample – extractant ratio

1. distilled water

2. saturated calcium sulphate

3. m – ammonium acetate

pH and conductivity are determined on the water extract, nitrogen, phosphate and potash are determined on the filtered calcium sulphate extract and calcium and magnesium on the filtered ammonium acetate extract.

The recommended levels of nutrients for tomatoes grown in a peat substrate are:

nitrogen	500–100 ppm
phosphate	30–50 ppm	(13–22 ppm P)
potash	350–450 ppm	(290–374 ppm K)
calcium	1000 ppm
magnesium	200 ppm
calcium/magnesium ratio	5:1
ph	5.5–6.0
pC	3.0–2.9	(conductivity 1000–1300 micro-mhos,10–13CF)

Symposium on Substrates in Horticulture other than Soils In Situ

G.C.S. Wilson

https://doi.org/10.17660/ActaHortic.1980.99.29