%0 Research Notes
%T Compaction of growth media based on Sphagnum peat during one-year culturing of container seedlings
%A Heiskanen, Juha
%D 1995
%J Suo - Mires and peat
%V 46
%N 3
%U http://suo.fi/article/9748
%X Changes in bulk density and water retention during one-year culturing of container seedlings were studied in pure, low-humified Sphagnum peat and in peat-based two-component growth media. In all growth media, the bulk density increased slightly with time. The corresponding decrease in total porosity was negligible (< 1 %-unit for pure peat). At matric potentials < -1 kPa, water retention of growth media tended to increase somewhat with time. On the other hand, shrinkage at desorption decreased during seedling culturing. The results suggest that, from the standpoint of seedling growth, the structure of growth media based on Sphagnum peat does not markedly change or deteriorate during one-year culturing of seedlings. However, in seedling culturing peat growth media containing hydrogel may possess restricted aeration due to excess water retention, while addition of coarse textured materials, such as perlite, to peat can increase aeration.

Key words: nursery management, soil physical properties, shrinkage, substrate, water retention