Nutritional aspects in bioassays according to 
EN 16086-1

W.H.C. Geuijen, J.B.G.M. Verhagen
The European Standard EN 16086-1 is a method to determine plant response of soil improvers and growing media or constituents thereof. This method describes two pot experiments: direct testing with a sample undiluted or diluted with peat and indirect testing by saturating perlite using an extract of the original sample in nutrient solution. In earlier experiments according to the standard, limited growth due to nutrition was observed. Therefore, effect of green waste compost and pumice on growth of Chinese cabbage (Brassica rapa var. pekinensis) was tested, with and without additional fertilization in the last phase of the experiment. To test green waste compost, the direct method was used. Reference sphagnum peat was fertilized and limed at the start of the test according to the standard. Green waste compost was mixed with peat (20:80% v/v) and fertilization was adjusted for the nutritional effects of green waste compost. Part of the plants of both treatments were additionally fertilized from day 14 onwards. To test pumice, the indirect method was used. An extract of pumice in nutrient solution was prepared, in which the nutrient solution was adapted for the supposed adsorption of potassium and phosphate by pumice. The extract was used for watering, the reference was watered with nutrient solution. When the extract was used up (day 11), half of the plants of both treatments were watered with water and the others with nutrient solution. Without additional fertilization, growth was limited by nutrition in both the direct and indirect test. To prevent misinterpretation about the effect of test materials on plant growth, additional fertilization and analyses of mixtures and solutions are necessary for pot experiments carried out according to EN 16086-1.
Geuijen, W.H.C. and Verhagen, J.B.G.M. (2021). Nutritional aspects in bioassays according to 
EN 16086-1. Acta Hortic. 1305, 193-200
DOI: 10.17660/ActaHortic.2021.1305.27
nutrition, pot test, extract test

Acta Horticulturae