Container Height and Douglas Fir Bark Texture Affect Substrate Physical Properties

Abstract

<jats:p>A study was conducted to quantify the effect of substrate texture on water-holding capacity of douglas fir [<jats:italic>Pseudotsuga menziesii</jats:italic> (Mirb.) Franco] bark (DFB) in containers of varying height. Medium (less than 2.2 cm) and fine (less than 0.9 cm) DFB were packed into 7.6 cm i.d. aluminum cores 3.8, 7.6, and 15.2 cm tall to determine container capacity (CC) and air space (AS) at varying container heights. Increasing container height resulted in a linear decrease in CC and a linear increase in AS. Fine texture DFB bulk density (D<jats:sub>b</jats:sub>) increased 18% with increasing container height, whereas D<jats:sub>b</jats:sub> of medium texture DFB was unaffected. Water-holding capacity decreased 20% and 42% in medium and fine textured DFB, respectively, with increasing container height from 3.8 to 15.2 cm. A second study was conducted to investigate water distribution in a 15.2-cm tall container for a given substrate texture. Polyvinyl chloride cores (15.2 cm tall × 7.6 cm i.d.) were packed with the same substrates, drained to CC, frozen, and sawed into 2.5-cm sections to determine water-holding capacity at each height. A finer substrate texture increased the amount of water throughout the container profile, but percent of total water for each strata remained similar. Container height and plant size (i.e., transplant or salable), in relation to substrate texture, should be considerations when producing containerized crops. In addition, bark texture alters water-holding capacity and water distribution within the container, ultimately affecting water management practices.</jats:p>

Organic Growing Media: Constituents and Properties

“…In addition to the inherent properties of a growing medium, container size and shape may have a marked influence on the air/water ratio of the substrate. In a pot or other container, a substrate moisture gradient exists where, due to gravitational effects, air content decreases and moisture increases from the top to bottom of the container (Fonteno, 1996; Owen and Altland, 2008). For example, in a 1:1 peat/vermiculite mixture filling containers 2.5 and 15 cm high, the air volume increased from 2 to 20% (Fonteno, 1988).…”

Stem Cutting Propagation in Whole Pine Tree Substrates

“…The proportion of fine particles doubled for PB:PM and WPT:PM compared with PB and WPT, respectively. It has been reported that substrate particles less than 0.5 mm can have a significant effect on substrate air space and container capacity (Jackson et al, 2010;Owen and Altland, 2008). The greater proportion of fine particles most likely resulted in the greater substrate container capacity and lower substrate air space of the substrates amended with PM.…”

Water and Air Relations in Propagation Substrates

“…1). In addition to MRCs, the evaporation method has been used to describe hydraulic conductivity and substrate porosity (Fields et al, 2016(Fields et al, , 2017Naasz et al, 2005;Owen and Altland, 2008;Schindler, 1980;Schindler et al, 2016).…”

“…Moisture retention curve by frozen column method. The frozen column method was used to generate MRCs of the three substrates (peat, rockwool, and foam) at container capacity, with four replicates per substrate (Altland et al, 2010;Owen and Altland, 2008). Peat was filled into 3.8-cmdiameter clear plastic tubes of 30.5-cm length and dropped at a height of 6 cm three times to provide consistent compaction.…”

“…An alternative method to generate an MRC is the use of the frozen column method, whereby the substrate is brought to field capacity, frozen, and then sectioned to quantify VWC and VAC within each vertical section (Altland et al, 2010;Dane and Hopmans, 2002;Owen and Altland, 2008). The VWC using the frozen column method allows a comparison between the water potential from the column height to the water potential measured using a tensiometer.…”