seed. Evans and Gachukia (2004) demonstrated that PBH could be successfully used as an alternative to perlite in the root substrate for the production of several ornamental species. However, the physical properties of PBH-amended sphagnum peat
Michael R. Evans and Mary M. Gachukia
Shelly D. Dueitt and Steven E. Newman
Rice hulls, a by-product of the rice milling process, were used at various rates to substitute sphagnum peat moss in greenhouse media. Previous studies demonstrated that media containing rice hulls replacing the vermiculite fraction grew plants equal to or better than traditional peat vermiculite blends. The objective of this study was to determine if rice hulls can replace sphagnum peat moss in a greenhouse medium. Physical properties, including bulk density, total pore space, and water retention were determined in media blended with fresh or aged rice hulls, sphagnum peat moss, and vermiculite. The bulk density of the media increased with increasing levels of fresh rice hulls. The pore space in media containing both fresh and aged rice hulls decreased over time during the crop production cycle and the pH increased.
Carolyn F. Scagel
Using several different ericaceous ornamental species, we compared the growth, mineral nutrition, and composition of plants in response to growing media amended with varying proportions of sphagnum moss peat (peat) or coir dust (coir). Plants were grown for 16 weeks in media consisting of 80% composted Douglas fir bark with 20% peat, 20% coir, or 10% peat and 10% coir. Sixteen weeks after planting, decreases in extractable P were larger in peat-amended medium than the coir-amended medium, while decreases in extractable NH4-N and NO3-N were larger in the coir-amended medium. In general, leaf and stem dry weight, the number of leaves and stems, and total stem length increased with increasing proportion of coir in the medium while root dry weight either increased (Kalmia latifolia), decreased (Rhododendron, Gaultheria), or was not influenced by increasing the proportion of coir in the medium. The composition of the growing medium also influenced aspects of plant marketability and quality including: leaf greenness (SPAD), plant form (e.g., number of leaves per length of stem), and partitioning of biomass (e.g., root to shoot ratio). Nutrient uptake and fertilizer use was significantly different between the media types. Depending on the cultivar, we found that the coir-amended medium resulted in higher uptake or availability of several nutrients than peat-amended medium. Up take or availability of N, P, K, Ca, and S was enhanced for several cultivars, while uptake or availability of Mg, Fe, and B was similar between media types. Most cultivars/species growing in the coir-amended medium had higher production or accumulation of proteins and amino acids in stems than plants growing in peat-amended medium, while the production of proteins and amino acids in roots was lower in plants growing in coir-amended than in peat-amended medium. For the cultivars/species we tested, coir is a suitable media amendment for growing ericaceous plants and may have beneficial effects on plant quality.
Michael R. Evans
Plant growth was evaluated in substrates containing varying proportions of processed poultry feather fiber (feather fiber). `Cooler Blush' vinca (Catharanthus roseus) and `Orbit Cardinal' geranium (Pelargonium × hortorum) dry shoot and dry root weights were not significantly different among plants grown in sphagnum-peat-based and perlite-based substrates containing 0% to 30% feather fiber. `Pineapple Queen' coleus (Coleus blumei) dry shoot weights were not significantly different among plants grown in substrates containing 0% to 50% feather fiber. Coleus dry root weights were not significantly different among the substrates containing 0% to 40% feather fiber. `Better Boy' tomato (Lycopersicon esculentum) dry shoot weights were not significantly different among the substrates containing 0% to 30% feather fiber. Tomato dry root weights were not significantly different among the substrates containing 0% to 30% feather fiber, but tomato grown in substrates containing 40% to 60% feather fiber had significantly lower dry root weights than tomato grown in substrates containing 0% to 30% feather fiber. `Salad Bush' cucumber (Cucumis sativus) dry shoot and dry root weights were not significantly different between plants grown in 0% to 50% feather fiber, but those gown in substrates containing 60% feather fiber had significantly lower dry shoot weights than those grown in substrates containing 0% feather fiber. Dry shoot and root weights of coleus and tomato grown in SB-300 substrate amended with 20% or 30% feather fiber were not significantly different from coleus and tomato grown in SB-300 without feather fiber. Dry shoot and dry root weights of coleus and tomato were significantly lower for plants grown in SB-300 amended with 40% feather fiber than for plants grown in SB-300 without feather fiber. For all species tested, plants grown in substrates containing up to 30% feather fiber were not significantly different from those grown in substrates containing 0% feather fiber and were of marketable qualities.
A. Jeremy Bishko, Paul. R. Fisher and William R. Argo
The objective was to systematically quantify the dose response from applications of several alkaline materials recommended for raising pH in acidic media. A 70 peat: 30 perlite (by volume) medium was mixed with a pre-plant nutrient charge, a wetting agent, and between 0 and 1.5 kg·m3 of a dolomitic hydrated lime resulting in six starting-pHs between 3.4 and 6.4. The supernatant from a solution of Ca(OH)2, 2.5 to 40 mL·L-1 of a flowable dolomitic limestone suspension, 99.5% KHCO3 between 0.6 to 9.6 g·L-1, 85% KOH between 0.056 and 0.56 g·L-1, 15N-0P-12K water-soluble fertilizer at 50 to 400 mg·L-1 N, and a distilled water control were applied at 60 mL per 126-mL container with minimal leaching as a single drench (except the 15N-0P-12K that was applied about every three days). All chemicals increased medium-pH within one day, and pH remained stable until day 28 except for Ca(OH)2 which showed a 0.2 unit decrease in pH from day 1 to 28. The Ca(OH)2 and KOH drenches raised medium-pH by less than 0.5 units, and there was a slight decrease in pH from the 15N-0P-12K for starting-pHs lower than 5.0. Flowable dolomitic lime and KHCO3 raised pH by up to 2 pH units, averaged across starting pHs and 1-28 days after application. The effect on medium-pH increased as concentration of flowable lime and KHCO3 increased. Effect of flowable lime was greater (up to 2.9 units) at lower starting-pHs, whereas KHCO3 was less affected by starting-pH. Medium-EC increased by <0.6 dS·m-1 following single applications of all solutions.
R.R. Tripepi, M.W. George and A.G. Campbell
Pulp and paper sludge is a byproduct of paper production, yet this fibrous material may be suitable as an alternative amendment for peat moss in container media. Newsprint mill sludge was composted 6 weeks and cured before use. One-year-old seedlings of lilac (Syringa vulgaris L.) and amur maple (Acer ginnala Maxim.) as well as rooted cuttings o cistena plum Prunus × cistena Hansen) were planted in 3-liter pots that contained a barksand (2:1 by vol) mix, 25% or 50% peatamended media, or 25% or 50% sludge-amended media. After 14 weeks outdoors, shoot dry weight and changes in plant height were measured. All species planted in sludge-amended media grew as well as those potted in peat-amended media or the bark:sand mix. In fact, some species grew best in sludge-amended media. Lilac seedlings planted in 25% sludge produced almost double the amount of shoot dry weight and were 80% taller than plants in the bark:sand mix or 25% peat. Maple plants grown in 500% sludge produced over 100% or 3590 more shoot dry weight than those grown in 25% or 50% peat-amended media, respectively. Plum cuttings pottedin25910 sludge grew at least 53% taller than plants grown in either peat-amended medium. These results indicate that composted newsprint sludge can be used as a peat moss substitute in a container medium for the landscape plants tested.
Andrew A. Waber and Michael R. Evans
Euphorbia pulcherrima `Freedom' (poinsettia) were grown in coir dust, sphagnum peat, and perlite at the following ratios (respectively) 20:0:80, 40:0:60, 60:0:40, 80:0:20, 0:20:80, 0:40:60, 0:60:40, and 0:80:20 (v/v) substrates. Days to anthesis were not significantly different between substrates. Heights were greater for plants produced in 80% coir compared to plants grown in 80% peat. Overall, plants grown in coir-based substrates were taller than plants grown in peat-based substrates. Plants grown in 60% coir had a greater number of lateral shoots, increased shoot fresh weight and increased bract area compared to plants grown in 60% peat. Overall, plants grown in coir-based substrates had greater shoot fresh weights compared to plants grown in peat-based substrates. Lilium longiflorum `Nellie White' (lily) plants were grown in 40:0:20:40, 0:40:20:40, 0:57:14:28, 0:73:9:18 (v/v sphagnum peat: coir dust: loam: perlite) substrates. As the proportion of coir in the substrate increased, height, and shoot and root fresh weights increased. Nodes to flower, days to flower, and number of flowers were not significantly affected by substrate.
G.H. Neilsen, J. Beulah, E.J. Hogue and R. Utkhede
The effects of various nonfumigant planting-hole treatments on growth and yield of apple (Malus domestics Borkh.) trees were measured during the first 3 years after planting. Eight orchards diagnosed as having a replant problem were monitored. First-year shoot growth, the number of blossoms in the second year (inmost orchards), and first-year trunk cross-sectional area increment (TCAI) in 50% of test orchards were increased by monoammonium phosphate (MAP) fertilizer+ peat, MAP+ mancozeb, or MAP + peat + a bacterial antagonist. By the end of year 3, TCAI generally was not affected by treatments, but treatments resulted in more blossoms by the third season in two of seven orchards that blossomed in the second season. Cumulative yield after 3 years increased significantly in only three orchards, with the best treatment, MAP+ peat, resulting in cost recovery in only one orchard. Inadequate K or Cu nutrition may have reduced growth in some of the orchards, which were characterized by a wide range in yields, independent of planting-hole treatment.
Gretchen E. Mills and Allen V. Barker
For optimum plant growth in containers, adequate plant nutrition is essential. Objectives of this research were to determine the optimum fertilization of tomatoes (Lycopersicon esculentum Mill.) in a peatbased medium and to assess plant nutrition by plant and media analysis. Tomato seedlings ('Heinz 1437') were transplanted (one plant per pot) into 2-L pots filled with a peat-based medium. The medium was fertilized with a progressive array of soluble fertilizers to supply N at 0, 50, 100, 150, or 200 mg·L-1 of solution with concomitant proportional increases of other macronutrients with each increase in N (P at 0, 10, 20, 30, or 40; K at 0, 40, 80, 120, or 160; Ca at 0, 50, 100, 150, or 200; and Mg at 0, 12, 24, 36, or 48 mg·L-1). The plants were irrigated starting with 100 mL fertilizer solution per day and increasing to 200 mL per day as plant growth progressed. The tomatoes were harvested at three stages of growth (five-leaf stage, flower initiation, and fruit initiation) for analysis of growth and composition. Samples of media for nutrient analysis were taken at each growth stage. Plant biomass increased linearly as fertilizer level increased or as time progressed. Generally, concentrations of nutrients in the medium increased linearly with increases in nutrients in the solutions. With time, N concentrations in media rose, but P, K, Ca, and Mg in the media fell. Concentrations of N, P, or K in leaves increased as nutrition increased, but Mg or Ca in leaves had no significant changes with increased nutrient supply. The N, P, Ca, and Mg in tissues fell, but K rose with time. Assessment of plant nutrition was best at flower initiation, with assessments at the other stages of development being judged as untimely or excessively variable. For optimum growth, critical concentrations of nutrients in the media (mg·kg-1) at flower initiation were judged to be 30 NO3-N, 30 P, 300 K, 2600 Ca, and 800 Mg and in leaves (g·kg-1) to be 35 N, 10 P, 70 K, 35 Ca, and 20 Mg. Optimum fertilization to reach these critical concentrations was reached with the third level (the regime with 100 mg N/L) or higher levels of nutrition.
Cale A. Bigelow, Daniel C. Bowman and D. Keith Cassel
sand-based rootzones are specified for golf course putting greens because they resist compaction and maintain drainage, even under heavy traffic. Although sands provide favorable physical properties, nutrient retention is generally poor and soluble nutrients like nitrogen (N) are prone to leaching. Laboratory experiments were conducted to evaluate several inorganic soil amendments (clinoptilolite zeolite (CZ), diatomaceous earth, and two porous ceramics), which varied in cation exchange capacity (CEC), and sphagnum peat for their ability to limit N leaching. Columns (35 cm tall × 7.6 cm diameter) were filled with 30 cm of sand-amendment mixtures (8:2 v/v) and NH4NO3 was applied in solution at a N rate of 50 kg·ha-1. Leaching was initiated immediately using 2.5 pore volumes of distilled water in a continuous pulse. Leachate was collected in 0.1 pore volume aliquots and analyzed for NH4 +-N and NO3 --N. All amendments significantly decreased NH4 + leaching from 27% to 88% which was directly proportional to the CEC of the amendments. By contrast, NO3 - losses were consistently high, and no amendment effectively decreased loss compared to nonamended sand. Two amendments with the highest CECs, CZ and a porous ceramic, were selected to further study the effects of amendment incorporation rate, depth, and incubation time on N leaching. Ammonium but not NO3 - leaching was decreased with increasing amendment rate of both products. At 10% amendment (v/v) addition, only 17% to 33% of applied NH4 + leached from the amended sands. Depth of amendment incorporation significantly affected NH4 + leaching, with uniform distribution through the entire 30 cm tall column being more effective than placement within the upper 2.5 or 15 cm. Allowing the NH4NO3 to incubate for 12 or 24 hours following application generally did not affect the amount leached. These results suggest NH4 +-N leaching is inversely related to CEC of the root-zone mixture and that uniform distribution of these CEC enhancing amendments in the root-zone mixtures reduced N leaching to a greater extent than nonuniform distribution.