UTILIZATION OF TEMPE CELLS IN DETERMINATION OF PHYSICAL PROPERTIES OF PEAT BASED SUBSTRATES

Physical properties of moderately decomposed sphagnum peat materials amended with 15 or 30% perlite of varying particle size were assessed in Tempe pressure cells maintained at 10, 50 and 100 mbar.
Total porosity (TPS) was calculated from bulk and particle density measurements.
Air space (AS) was determined after equilibrating saturated samples at 10 mbar.
Easily available water (EAW) was released while increasing pressure from 10 to 50 mbar.
Water buffering capacity (WBC) was water released between 50 and 100 mbar, leaving residual water (RW) in the sample.
Adding 30% perlite of size fraction exceeding 0.30mm improved AS and EAW as compared to pure peat or 15% ammended peat.
Extra-fine perlite (<0.30mm) had the opposite effect.
TPS did not vary importantly among substrates, averaging 94%. Considerable amount of perlite containing very low proportion of dust should be added to moderately decomposed sphagnum peat to improve substrate quality.
Tempe pressure cells can be used successfully to formulate peat-perlite substrates on the basis of physical properties.

Symposium on Substrates in Horticulture other than Soils in situ

P. Joyal, J. Blain, L.E. Parent

https://doi.org/10.17660/ActaHortic.1989.238.6