GROWTH AND FOLIAR NUTRITION OF WESTERN RED CEDAR FERTILIZED WITH SEWAGE-SLUDGE, PULP SLUDGE, FISH SILAGE, AND WOOD ASH ON NORTHERN VANCOUVER-ISLAND

The fertilizer efficacy of a variety of organic wastes was tested in a 9-year-old plantation of western red cedar (Thuja plicata Donn ex D. Don) growing on a cutover of cedar-hemlock (Tsuga heterophylla (Raf.) Sarg.) forest on northern Vancouver Island. Seven treatments were comp ared: municipal sewage sludge, sewage sludge plus pulp sludge, fish si lage and wood ash, silage and ash plus pulp sludge, wood ash alone, am monium nitrate with triple super phosphate, and control (untreated). E ach treatment was replicated three times. Rates of application were 22 5 kg N.ha(-1) in the inorganic fertilizer and about 500 kg N.ha(-1) in the organic wastes (except wood ash). The height and diameter of the cedar trees 2 years after fertilization were greatest in the plots tre ated with inorganic fertilizer (average height was 274 cm, vs. 211 cm in control plots; average diameter at 30 cm was 49 mm, vs. 34 mm in co ntrol plots). Smaller but significant growth responses were achieved w ith sewage sludge and fish silage plus ash. Mixtures of sewage sludge or silage with pulp sludge produced smaller height growth responses, b ut did not affect diameter growth. Wood ash alone had no effect on tre e growth. All treatments except wood ash increased the concentrations of macronutrients in foliage. Foliar N concentrations were greatest in trees treated with fish silage or inorganic fertilizer. Stagnated pla ntations of western red cedar appear to provide an opportunity for rec ycling these organic wastes.