Production of jack pine, Pinus banksiana, bark compost for use as nursery container media

Rowat, Christopher Allan
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University of Guelph

Jack pine ('Pinus banksiana') bark was windrow composted at two GRO-BARK composting facilities for 190 and 260 days respectively, and subsequently comprised 90% (vol.) of horticultural container media to evaluate the effects of mineral N addition, particle size reduction (PSR), and water management on composting conditions and growth of three species of woody ornamentals. Tub-grinding bark feedstock with a screen size <=10 x 15 cm resulted in acceptable maintenance of temperature during composting. pH increased during composting from 3.9 to 4.9 and 6.3 for treatments with and without urea addition, respectively. Maximum N immobilization was estimated at 0.28 kg N/m3. Plant growth of all species increased with N addition either prior to or post composting, and to a lesser extent with increasing PSR. All media were characterized as having a high air filled porosity which was greater in media produced with bark coarsely ground than with fine.

jack pine, bark compost, nursery container media, windrow composted, woody ornamentals