PARTICLE SIZES RELATED TO PHYSICAL PROPERTIES OF PEAT-BASED SUBSTRATES

To adequately guide components selection and growing media manufacturing for horticultural production, reliable indicators of substrate quality are still needed.
Given the importance of screening substrate constituents to improve growing media quality, an attempt was made to correlate the mass of the different particle sizes and some of the key physical properties of substrates (air-filled porosity, saturated hydraulic conductivity, tortuosity or gas relative diffusivity). The objective of the study was to evaluate possible correlations between the mass of the different particle sizes and initial physical properties (measured prior to potting) of different peat blend along with peat-perlite and peat-sawdust substrates.
The overall analysis of substrates (n=28) indicated that intermediate (0.85 to 2 mm) and fine particles (less than 0.3 mm) fractions were significantly correlated to air-filled porosity but also with saturated hydraulic conductivity, gas diffusivity and pore tortuosity of substrates.
For the peat-perlite substrates, fine particles were solely negatively correlated to saturated hydraulic conductivity.
On the contrary, for both sawdust and pure peat mixes, intermediate (0.85 to 2 mm) and fine particles (less than
0.3 mm) fractions remained strongly and significantly correlated with water (saturated hydraulic conductivity) and gas (pore tortuosity, gas diffusivity) transfer parameters.
Consequently, selection and preparation of growing media could be based on the particle size distribution indicator, taking into account the shape and the possible interaction between the different types of particles considered.

International Symposium on High Technology for Greenhouse Systems: GreenSys2009

R. Naasz, P. Bussières

air-filled porosity, gas relative diffusivity, hydraulic conductivity, particle-size distribution

https://doi.org/10.17660/ActaHortic.2011.893.109