Eastern Red-Cedar (Juniperus virginiana) as a Substrate Component for Container Production of Woody Plants

In many parts of the United States, eastern red-cedar (J. virginiana) is considered a weed species that will establish on unmanaged land and out-compete native grasses.  Throughout the Great Plains and Midwest, eastern red-cedar is reducing available land for grazing, altering the soil hydrology, and affecting vertebrate populations.  A thriving industry has arisen to rid infested pastures of eastern red-cedar.  The three step process entails; 1) cutting all plants off at the soil line, 2) allowing cut plants to dry for one year, and 3) grinding the aged plants.  The resulting stockpiles of eastern red-cedar chips may be a potential amendment in container substrates.  This is particularly important in regions of the country where pine (Pinus) trees are scarce.  This work describes the use of eastern red-cedar as a container substrate component.  Eastern red-cedar chips were ground to pass a 2.0 cm screen.  The chips were incorporated at 0, 5, 10, 20, 40, or 80% into a 8 pine bark : 1 sand (by vol) substrate by reducing the bark component.  A controlled release fertilizer was incorporated at 0.81 kg N•m^-3 or 1.6 kg N•m^-3 and urea (46-0-0) was incorporated at 0 or 0.4 kg N•m^-3.  Seedling Chinese pistache (Pistacia chinensis) and Indian-cherry (Frangula caroliniana) were potted into 3.8 L containers with one of the 24 substrate combinations.  The response of the two species was similar and only growth data for Chinese pistache is presented.  After 20 weeks, data for height, shoot dry weight, and root dry weight were gathered.  Plant height and shoot weight were affected by eastern red-cedar amendment only.  Plants growing in 10% (37.0 cm) and 80% (33.8 cm) eastern red-cedar were shorter than plants growing in 0% (42.9 cm).  All other amendment ratios produced plants with equal or greater height.  A similar trend followed for shoot weight.  Only plants growing in 10% (15.9 g) and 80% (15.4 g) eastern red-cedar had a shoot weight less than plants growing in 0% (17.8 g).  Root weight was greater for plants in substrates amended with 0.81 kg N•m^-3 when eastern red-cedar was 0, 5, 10, or 20% of the substrate.  However, when eastern red-cedar was 40% or 80% of the substrate, root weight was greater when amended with 1.6 kg N•m^-3.  There were no visible signs of nutrient deficiencies, substrate shrinkage, or allelopathy.  Further investigations are warranted to explore the use of eastern red-cedar as a substrate amendment.