The Hydration Efficiency of Two Pine Tree Substrate Components under Dry Conditions

Pine tree substrate components are becoming more prevalent in greenhouse substrates. However, no research has been conducted to determine their wettability. In this study, the hydration efficiency of two differently manufactured pine tree substrate components were tested under dry conditions. Hydration efficiency was determined by developing a wetting curve from 10 hydration events and comparing these to container capacity values.  One of the pine tree substrate components was manufactured to simulate the water holding characteristics of peat (SPW) while the other pine wood component was made to perform like an aggregate similar to perlite (PWC).  These two components were compared to peat moss and aged pine bark. These four components were tested at 25% moisture content at four different wetting agent rates in order to determine their wettability at what is considered to be hydrophobic moisture content levels for both peat and pine bark. Wetting agent rate did not affect container capacity in the two pine tree substrates or the pine bark, but wetting agents did affect the container capacity of peat. Peat showed high levels of hydrophobicity, not reaching container capacity until the tenth hydration event. Both of the pine tree substrate components as well as the pine bark reached container capacity at all wetting agent levels between the second and fifth hydration event. The PWC and the aged pine bark had similar container capacities; the SPW water holding capacities was higher. The peat with any rate of wetting agent had higher container capacity than all of the other components. However with no wetting agents, peat at 25% moisture content had the lowest container capacity. The two wood components demonstrated little hydrophobicity compared to peat and bark and had better hydration efficiency.