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Substituting Pine Wood for Pine Bark Affects Physical Properties of Nursery Substrates

Altland, James E
Hortscience 2012 v.47 no.10 pp. 1499
Pinus, bark, branches, bulk density, container-grown plants, forest nurseries, growing media, irrigation management, particle size distribution, porosity, water content, wood, Ohio
Pine bark (PB) is currently imported from southern U.S. states to those in the upper Midwest and Northeast U.S. Alternatives to pine bark that are regionally abundant and sustainable are needed for nursery substrates. The objective of this research was to determine the influence of chipped and hammermilled pine trees (excluding branches and needles) on substrate physical properties when substituted partially or wholly for pine bark in substrates typical of Ohio. Four cooperating nursery sites, each with unique substrates comprised primarily of pine bark, were recruited to use pine wood as a substitute for 0%, 50%, or 100% of the pine bark fraction in their substrate. All other physical and chemical amendments used traditionally at each site were incorporated. Physical properties including particle size distribution (PSD), air space (AC), container capacity (CC), total porosity (TP), unavailable water (UAW), bulk density (Db), and moisture characteristic curves (MCC) were determined for each substrate at each cooperator site. Pine wood was generally more coarse than all but one of the PB materials used by the four cooperating sites. Amendment with PW did not have any consistent or predictable effect on AS, CC, TP, or Db of the resultant substrates. Pine wood had little identifiable effect on plotted MCC, although it reduced calculated easily available water in one substrate. It was concluded that substitution of PB with PW can result in changes to substrate physical properties that might lead to irrigation management changes, but none of these changes were considered negative or drastic enough to cause physical properties to be outside of acceptable ranges.