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.
Peter Purvis, Calvin Chong, and Glen Lumis
Joanna Gils, Calvin Chong, and Glen Lumis
Ninebark [Physocarpus opulifolius (L.) Maxim] was grown on troughs under greenhouse conditions in 2.5-L containers filled with 100% composted pine bark and fertigated with drip irrigation using the following nutrient solutions: 1) a complete (control) solution, electrical conductivity (EC) of 1.75 dS·m–1, nonrecirculated; 2) solution as in treatment 1 but recirculated; 3) unamended municipal solid waste compost (MSW) leachate, EC 1.75 dS·m–1, recirculated; 4) solution as in treatment 3 amended in order of priority with NO3-N, NH4-N, P, K, Ca and/or Mg, to match the concentrations in the complete solution, EC 2.60 dS·m–1, recirculated; 5) unamended turkey litter compost (TLC) leachate, EC 1.75 dS·m–1, recirculated; and 6) solution as in treatment 5 amended as in treatment 4, EC 2.40 dS·m–1, recirculated. Among the four recirculated compost leachate treatments, shoot (stems and leaves) dry weight of ninebark was least with the unamended MSW, intermediate with amended MSW, and greatest but similar with both unamended and amended TLC. The most growth occurred with the recirculated control solution. Among the four leachate treatments, ninebark grew acceptably well only with recirculated unamended TLC, and was similar to that with the nonrecirculated control solution. Three treatments (nonrecirculated control, recirculated control and unamended TLC) showed no nutrient toxicity or deficiency symptoms. Poorer growth responses in the other treatments (amended TLC, amended MSW and unamended MSW) were related primarily to excess salts and/or nutritional disorders due to imbalance(s) in one or more nutrients.
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).
Mohammed Z. Alam, Calvin Chong, Jennifer Llewellyn, and Glen P. Lumis
To minimize fertilizer and water use, and NO3-N runoff from container culture, growth, and nutrient status of forsythia (Forsythia ×intermedia Zab. ‘Spring Glory’) in No. 2 containers were compared in response to a controlled-release fertilizer (CRF; Nutricote 18-6-8 100-day at rates of 2, 4, and 6 kg·m−3) and placements (incorporation and topdress) under three irrigation strategies [drip-irrigated low (25% or less) leaching fraction (DrLoLF), hand-sprinkled low leaching fraction (HsLoLF), and hand-sprinkled high (50% or less) leaching fraction (HsHiLF)]. In a coexperiment under drip irrigation only, forsythia response was also examined under incorporation, topdress, and dibble fertilizer placements with the same CRF rates applied as single or split dose. Dibble fertilizer placement was superior to both incorporation and topdress in this order. Maximum growth of forsythia occurred at rates of 4.7 kg·m−3 with dibble. With incorporation and topdress, maximum growth was not achieved even at the 6 kg·m−3 maximum rate tested. Forsythia grew better with incorporated than with topdressed CRF with the DrLoLF treatment. The response was reverse with HsHiLF or showed no differences with HsLoLF. Under drip irrigation, greater concentrations of NO3-N generally leached from incorporation and dibbled containers in this order than from topdress. Less nitrate was leached from the topdressed containers because less was released from the CRF prills. At the 6 kg·m−3 CRF rate, total cumulative NO3-N leachings were 76, 85, and 22 kg·ha−1 (45 × 45-cm container spacing) for dibbling, incorporation, and topdress, respectively, under drip irrigation. Split application of CRF greatly reduced NO3-N in leachate, although plant growth also was reduced as a result of less availability of and uptake of nutrients under this strategy.