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Calvin Chong* and Peter Purvis

Silverleaf dogwood (Cornus alba L. `Argenteo-marginata'), forsythia (Forsythia × intermedia Zab. `Lynwood Gold'), and weigela (Weigela florida Bunge A.DC. `Red Prince') were grown in #2 (6-L) containers filled with 100% bark or bark mixed with 20%, 40%, or 60% (by vol.) each of raw paper mill sludge (RB group), composted paper mill sludge (CB group), a proprietory paper mill sludge-derived compost (PB group), and municipal compost (MB group). A fifth substrate group (MH) consisted of 100% hemp chips or hemp chips mixed with the same rates of municipal compost. The containers were trickle-irrigated and fertilized with a controlled-release fertilizer. Among the bark-amended groups, growth was highest for dogwood and forsythia with PB, increasing dramatically and peaking at ca. 40% rate (68 and 94 g/plant top dry weight, respectively). Growth of these species was intermediate with MB and CB and least with RB, increasing to rates ≥ 50% in these groups, except for a nonsignificant response of dogwood to RB. Growth of weigela increased equally with PB and MB substrates up to ca. 40% (117 g/plant), but was unresponsive to rates of RB and CB. With the hemp-amended MH group, growth of all three species increased to rates ≥ 50% (62, 93, and 116 g/plant for dogwood, forsythia, and weigela, respectively). Growth of the three species over most rates of all substrate groups was similar to, or exceeded, that in 80% bark: 15% peat: 5% topsoil, a proven nursery mix. Top dry weight of all three species was positively correlated with soluble salts concentrations in the substrates at planting after first irrigation (0.23-1.72 dS·m-1, range over all substrates) and at various intervals during the season.

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Calvin Chong and Peter Purvis

Plug-rooted liners of deutzia (Deutzia gracilis), dogwood (Cornus alba `Argenteo-marginata'), forsythia (Forsythia×intermedia `Lynwood Gold'), and ninebark (Physocarpus opulifolius) were grown in 6-L containers. There were 36 different treatment substrates formulated in factorial combinations: two types of paper mill sludge (raw or composted) each at three rates (25%, 33%, or 50%, by volume) mixed with one of three sources of municipal waste compost (cities of Guelph, Toronto, or Waterloo; 25%, 33%, or 50%), and the remainder consisting of one of two base supplements (pine bark or 1-year-old wood chips; 50%, 33%, or 0%). The containers were trickle-irrigated and fertilized with a controlled-release fertilizer. Dogwood (no treatment interaction and responding only to the main effect of compost sources) grew equally well with Toronto and Waterloo composts, but less well with the Guelph compost. Ninebark tended to grow better with Toronto compost, intermediate or similar with Waterloo compost, and least with Guelph compost. Forsythia grew equally well in all bark-based substrates, regardless of sludge type and rate or compost source. With wood-chip-based substrates, however, forsythia grew better with Waterloo than with Guelph compost, and better with raw than with composted sludge when mixed with Toronto compost. Deutzia responded similarly to most substrates, but grew marginally better with raw than with composted paper sludge when Waterloo or Toronto compost was present. Despite these differences in species responses, all plants were of marketable size at the end of the season. There was no sign of nutrient toxicity or deficiency due to any of the substrates.

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Peter Purvis, Calvin Chong, and Glen Lumis

Plug-rooted liners of common ninebark [Physocarpus opulifolius (L.) Maxim.] were grown in 6-L nursery containers filled with 73% composted pine bark, 22% sphagnum peat moss, and 5% pea gravel (by volume). Plants were fertilized with Polyon (Nutryon) 17–5–12 (17N–2P–5K) 6-month controlled-release fertilizer at various rates (2.5, 4.5, 6.5, and 8.5 kg·m-3) pre-incorporated, topdressed, or dibbled (placed under the liner at potting). Plants were trickle-irrigated daily with low (0.4-L), middle (0.8-L), or high (2.0-L) volumes of water to maintain leaching fractions of <0.15, 0.25–0.35, or >0.60, respectively. Regression analysis indicated that growth of ninebark increased from 30 to 109 g/plant with increasing rates of incorporated fertilizer (mean over irrigation volumes), from 27 to 71 g/plant with topdress and from 59 to 103 g/plant with dibble. Electrical conductivity (EC, mean over five dates) of the leachate throughout the season was highest with dibble (0.85 dS·m-3), intermediate with incorporated (0.81 dS·m-3), and least with topdressed (0.76 dS·m-3). With low irrigation volumes, growth of ninebark increased from 42 to 81 g/plant with increasing rates of fertilizer (mean over methods), and from 39 to 105 g/plant with middle or high volumes (common regression curve). With low irrigation volumes, leachate EC increased from 0.74 to 0.94 dS·m-3 with increasing rates of fertilizer, and from 0.75 to 0.81 dS·m-3 with middle or high volumes.

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Calvin Chong, Glen Lumis, Peter Purvis, and Adam Dale

Rooted cuttings of `Antonovka' apple, `Lynwood Gold' forsythia, double-flowered kerria, common ninebark, `Goldfinger' potentilla, and `Red Prince' weigela were grown in 2-gal (6-L) nursery containers filled with 1:1 (by volume) of waste compost and composted pine bark, under three fertilizer regimes: 1) liquid nutrients [target concentrations in ppm (mg.L-1): NH4-N, 13; NO3-N, 100; P, 28; K, 120; Ca, 92; Mg, 13; Fe, 1.3; Mn, 0.27; Zn, 0.23; Cu, 0.05; B, 0.22; Mo, 0.05; Na, <50; Cl, <50; and SO4 <300] delivered and recycled twice per day via a computer-controlled multifertilizer injector; 2) same nutrient formula and concentration rate delivered fresh via the injector but without recycling; and 3) Nutryon (Polyon) 17-5-12 controlled-release fertilizer incorporated into the medium at a rate of 11 lb/yd3 (6.5 kg·m-3). With recycled liquid nutrients, all species grew the same or more than with nonrecycled nutrients, and generally the poorest growth was with controlled-release fertilizer. Foliar concentrations of K (all species), N (all species), P (forsythia, kerria, potentilla, and weigela), and Mn (forsythia, potentilla, and weigela) were higher in plants supplied with recycled and/or nonrecycled nutrients than in those supplied with controlled-release fertilizer, while foliar concentrations of Ca (ninebark and kerria) and Mg (apple, kerria, ninebark, potentilla, and weigela) were lower. Compared to nonrecycled liquid nutrients, the amounts of individual recycled nutrients were reduced by (percentage in brackets): NH4-N (30), NO3-N (78), P (76), K (46), Ca (93), Mg (96), Fe (52), Mn (43), Zn (55), Cu (60), B (83), and Mo (66).