BARK-HUMUS AS AN ALTERNATIVE TO PEAT AND SOIL IN THE PRODUCTION OF CUT FLOWERS
In this paper the term bark-humus is used to refer to crushed bark waste of conifers which, after adding lime chalk, nitrogen (in the form of urea) and bacteria (Eokomit), is composted and used as an unmixed medium for glasshouse plants or as a soil improver. Bark-humus was first introduced into Finland as an unmixed plant substrate in 1967 (Isomäki, 1967), and it was meant to give growers an alternative to peat in areas where the costs of transporting peat are high.
The following physical properties of bark-humus are worth mention: porosity 78–85%, water content 58–65%, air content 15–30% and volume weight 110–150 kg/cu. m. It can be assumed from these figures that bark-humus provides a good growing medium for roots, which was in fact proved to be so in our preliminary tests in 1967 (figure 1, Suhonen, 1967).