McDonald, M.A., B.J. Hawkins, C.E. Prescott, and J.P. Kimmins, 1994. Growth and foliar nutrition of western red cedar fertilized with sewage sludge, pulp sludge, fish silage and wood ash on northern Vancouver Island. Can. J. For. Res. 24:297-301.

The fertilizer efficacy of a variety of organic wastes was tested in a 9-yr-old plantation of western red cedar (Thuja plicata) growing on a cutover of cedar/hemlock (Tsuga heterophylla) forest on northern Vancouver Island, British Columbia. Seven treatments (municipal sewage sludge, sewage sludge plus pulp sludge, fish silage plus wood ash, fish silage plus wood ash plus pulp sludge, wood ash alone, ammonium nitrate with triple super phosphate, and an untreated control) were applied in December 1990 or March 1991. Each treatment was replicated three times. Inorganic fertilizer was applied at 225 kg N/ha and the organic fertilizers (except wood ash) at about 500 kg N/ha. Wood ash was applied at 5 t/ha. The height and diameter of cedar trees 2 years after fertilizer application were greatest in the plots treated with inorganic fertilizer (average height was 274 cm, vs. 211 cm in control plots; average diameter at height 30 cm was 49 mm, vs. 34 mm in control plots). Smaller but significant growth responses were achieved with (i) sewage sludge and (ii) fish silage plus ash. Mixtures of sewage sludge or fish silage with pulp sludge produced smaller height growth responses, but did not affect diameter growth. Wood ash alone had no effect on tree 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. It is concluded that stagnated plantations of western red cedar appear to provide an opportunity for recycling these organic wastes.