J. Heiskanen et al., EFFECTS OF MECHANICAL CONTAINER-FILLING METHODS ON TEXTURE AND WATER-RETENTION OF PEAT GROWTH MEDIA, Scandinavian journal of forest research, 11(4), 1996, pp. 351-355
Two commercial products of growth media made of light, low-humified Sp
hagnum peat were used to determine how six different container-filling
treatments with a mechanical filling machine affect the particle-size
distribution and water-retention characteristics of peat. It was show
n that, in particular, the feeding screw conveyor in the filling machi
ne used broke down the peat particles, resulting in a significant incr
ease in the proportion of <1 mm particles. The water retention and shr
inkage measured at desorption of the peat media were also found to cha
nge due to container filling, but these changes were relatively slight
. However, depending on the peat product, reduction in particle size a
ccompanied by heavy compaction can yield a marked increase in water re
tention, especially under wet conditions (at > -1 kPa matric potential
s), and correspondingly, decreased air-filled porosity. Consequently,
in plant culturing heavy mechanical methods of container filling can c
ause potential risk of restricted aeration to roots. These results sug
gest a need to develop gentler filling machines without screw conveyor
s.