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  • Author or Editor: Michael R. Evans x
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Two grades of ground bovine bone were evaluated as potential alternatives to perlite in horticultural substrates. The bulk density of small and large bone-amended substrates was significantly higher than equivalent perlite-amended substrates. Large and small bone increased the air-filled pore space of sphagnum peat. However, at 10% and 20% (v/v), neither size of bone resulted in as high an air-filled pore space as equivalent amounts of perlite. At 30% and 40%, incorporation of small bone resulted in a similar air-filled pore space as incorporation of equivalent amounts of perlite, and incorporation of large bone resulted in a higher air-filled pore space than incorporation of equivalent amounts of perlite. Water-filled pore space and water-holding capacities of substrates were inversely related to air-filled pore space. When placed in a moist substrate, mineral elements within the bone were able to leach into the substrate over time. Substrates amended with 40% large and small bone had significantly higher concentrations of ammonium (NH4 +), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), and chloride (Cl-) than the 40% perlite-containing substrates. Substrates amended with 40% large bone had similar concentrations of magnesium (Mg), sulfur (S), iron (Fe), and copper (Cu) while substrates amended with 40% small bone had higher levels of these elements than perlite-amended substrates. Substrate concentrations of nitrate (NO3 -), manganese (Mn), zinc (Zn), and boron (B) were not different among the substrates after 4 weeks in the greenhouse. The pH, electrical conductivity (EC) and NH4 + levels of bone-amended substrates increased to levels significantly higher than recommended and resulted in rapid mortality of `Orbit Cardinal' geranium (Pelargonium × hortorum), `Cooler Blush' vinca (Catharanthus roseus), and `Dazzler Rose Star' impatiens (Impatiens walleriana) plants grown in bone-amended substrates. Therefore, ground bovine bone was not a feasible alternative to perlite for use in horticultural substrates.

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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.

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Aggregates produced from finely ground waste glass [Growstones (GS); Earthstone Corp., Santa Fe, NM] have been proposed to adjust the physical properties of peat-based substrates. The GS had a total pore space (TPS) of 87.4% (by volume), which was higher than that of sphagnum peat and perlite but was similar to that of parboiled fresh rice hulls (PBH). The GS had an air-filled pore space (AFP) of 53.1%, which was higher than that of sphagnum peat and perlite but lower than that of PBH. At 34.3%, GS had a lower water-holding capacity (WHC) than sphagnum peat but a higher WHC than either perlite or PBH. The bulk density of GS was 0.19 g·cm−3 and was not different from that of the perlite but was higher than that of sphagnum peat and PBH. The addition of at least 15% GS to sphagnum peat increased the AFP of the resulting peat-based substrate. Substrates containing 25% or 30% GS had a higher AFP than substrates containing equivalent amounts of perlite but a lower AFP than substrates containing equivalent PBH. Substrates containing 20% or more GS had a higher WHC than equivalent perlite- or PBH-containing substrates. Growth of ‘Cooler Grape’ vinca (Catharanthus roseus), ‘Dazzler Lilac Splash’ impatiens (Impatiens walleriana), and ‘Score Red’ geranium (Pelargonium ×hortorum) was similar for plants grown in GS-containing substrates and those grown in equivalent perlite- and PBH-containing substrates.

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The objective for this research was to evaluate the growth of a long-term crop in biodegradable containers compared with traditional plastic containers using a subirrigation system. Plastic, bioplastic, solid ricehull, slotted ricehull, paper, peat, dairy manure, wood fiber, rice straw, and coconut fiber containers were used to evaluate plant growth of ‘Rainier Purple’ cyclamen (Cyclamen persicum) in ebb-and-flood subirrigation benches. The days to flower ranged from 70 to 79 and there were no significant differences between the plastic containers and the biocontainers. The dry shoot weights ranged from 23.9 to 37.4 g. Plants grown in plastic containers had dry shoot weights of 27.6 g. The dry shoot weight of plants grown in containers composed of wood fiber was 23.9 g and was lower than plants grown in plastic containers. The plants grown in the bioplastic, solid ricehull, slotted ricehull, paper, peat, dairy manure, rice straw, and coconut fiber containers had significantly higher dry shoot weights than plants grown in plastic containers. Dry root weights ranged from 3.0 to 4.0 g. The plants grown in the plastic containers had dry root weights of 3.0 g. Plants grown in paper and wood fiber containers had higher dry root weights than those grown in plastic containers. The only container that negatively affected plant growth was the wood fiber container. Plants preformed the best in solid ricehull, slotted ricehull, and coconut fiber containers based on dry shoot and dry root weights, but all containers were successfully used to produce marketable cyclamen plants.

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A series of soilless root substrates was formulated to contain either 20% composted pine bark or perlite and 0%, 10%, 20%, or 30% feather fiber, with the remainder being sphagnum peat. The substrates containing bark or perlite with 0% feather fiber served as the controls for the bark- and perlite-containing substrates respectively. For root substrates containing perlite, the inclusion of feather fiber increased the total pore space compared with the control substrate. For substrates containing bark, the inclusion of 10% or 20% feather fiber increased total pore space, but the inclusion of 30% feather fiber reduced total pore space. For substrates containing perlite, the inclusion of feather fiber increased the air-filled pore space compared with the control, and as the percentage feather fiber increased, air-filled pore space increased. For substrates containing bark, the inclusion of 10% or 20% feather fiber increased air-filled pore space, but air-filled pore space of the substrate containing 30% feather fiber was not different from the control. For all substrates, the inclusion of feather fiber reduced the water-holding capacity, but water-holding capacities for all substrates remained within recommended ranges. The bulk density of feather fiber-containing substrates was not different from the control except for the substrate containing 30% feather fiber with bark, which had a higher bulk density than its control without feather fiber. The difference in physical properties of the 30% feather fiber substrate with bark from its control substrate was attributed to the aggregation of the feather fiber when formulated with composted bark. Aggregation of feather fiber when blended into substrates at levels of 30% or higher would create difficulties in achieving uniform substrates.

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Ten substrates were formulated by blending perlite or parboiled fresh rice hulls (PBH) to produce root substrates (substrates) that contained either 20%, 30%, 40%, 50%, or 60% (by volume) perlite or PBH, with the remainder being sphagnum peatmoss. All substrates containing PBH had higher total pore space than substrates containing an equivalent amount of perlite. As the percentage perlite increased from 20% to 60%, the total pore space decreased. The total pore space increased as the amount of PBH increased to 50% and then decreased as the amount of PBH increased from 50% to 60%. The air-filled pore space was not different between substrates containing 20% perlite or PBH. However, the air-filled pore space was higher in PBH-containing substrates than in equivalent perlite-containing substrates when the amount of PBH or perlite was at least 40%. As the amount of perlite or PBH was increased, the air-filled pore space increased, but the rate of increase was higher for PBH-containing substrates. The 20% PBH-containing substrate had a higher water-holding capacity than the 20% perlite-containing substrate. However, at 30% or higher PBH, the PBH-containing root substrates had a lower water-holding capacity than equivalent perlite-containing substrates. As the percentage perlite or PBH was increased, the water-holding capacity decreased, but at a higher rate in PBH-containing substrates than in perlite-containing substrates. For all substrates except those containing 40% PBH or perlite, substrates containing PBH had lower bulk densities than equivalent perlite-containing substrates. The differences in bulk densities were not great enough to be of practical significance. Inclusion of PBH in the substrate provided for drainage and air-filled pore space as did perlite. However, less PBH would be required in a substrate to provide the same air-filled pore space as perlite when more than 20% perlite or PBH is used.

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A top coat is a lightweight substrate component used in seed germination. The seeds are typically placed on a substrate such as peat and then the seeds are covered with a layer of the top coating substrate. The top coat serves to maintain adequate moisture around the seeds and to exclude light. Vermiculite and cork granulates (1 mm) were used as top coat substrates for seed germination to determine if cork granulates could be successfully used as an alternative to vermiculite. The cork granulates had a bulk density of 0.16 g·cm−3, which was higher than that of vermiculite that had a bulk density of 0.12 g·cm−3 . Cork granulates had an air-filled pore space of 22.7% (v/v), which was higher than vermiculite which was 13.2%. The water-holding capacity of vermiculite was 63.4% (v/v), which was higher than that of cork granulates that was 35.1%. Seeds of ‘Rutgers Select’ tomato (Solanum lycopersicum), ‘Dazzler Lilac Splash’ impatiens (Impatiens walleriana), ‘Orbital Cardinal Red’ geranium (Pelargonium ×hortorum), ‘Better Belle’ pepper (Capsicum annuum), and ‘Cooler Grape’ vinca (Catharanthus roseus) were placed on top of peat and covered with a 4-mm top coating of either vermiculite or cork granulates. For tomato, impatiens, and vinca, days to germination were similar between seeds germinated using vermiculite and granulated cork as a top coat. Days to germination of geranium and pepper were significantly different with geranium and pepper seeds coated with cork granulates germinating 0.7 and 1.5 days earlier than those coated with vermiculite. For tomato, impatiens, and geranium, the number of seeds germinating per plug tray was similar between the top coats. Number of seeds germinating per tray for pepper and vinca were significantly different. Pepper had an average of 2.8 more seeds germinating per tray, and vinca had an average of 2.4 more seeds germinating per tray if seeds were germinated using granulated cork vs. vermiculite. For all species, dry shoot and dry root weights were similar for seedlings germinated using cork and vermiculite top coats.

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Substrates were formulated by blending parboiled fresh rice (Oryza sativa) hulls (PBH) or perlite with sphagnum peat (peat) to produce root substrates (substrates) that contained 20%, 30%, 40%, 50%, or 60% (by volume) PBH or perlite with the remainder being peat. After 0 (initial mixing), 4, or 8 weeks in a greenhouse environment, samples were taken and pH, electrical conductivity (EC), nitrate (NO3 ), ammonium (NH4 +), phosphorus (P), and potassium (K) were determined. As the amount of PBH or perlite in the substrate was increased, the pH increased. After 0 and 8 weeks, the pH of substrates containing up to 30% PBH or perlite had a similar pH. However, the rate of pH increase at these sampling times was higher than that of perlite so that substrates containing 40% or more PBH had a higher pH than equivalent perlite-containing substrates. At the week 4 sampling period, all substrates containing PBH had a higher pH than equivalent perlite-containing substrates. For all sampling times, the difference in pH between equivalent PBH and perlite-containing substrates was not high enough to be of practical significance. For all sampling times, EC increased as the amount of perlite was increased. Depending upon sampling time, the EC decreased or remained unchanged as the amount of PBH was increased. For all sampling times and substrates, EC was within acceptable ranges for unused substrates. Substrates containing PBH had higher NO3 levels than equivalent perlite-containing substrates. The NH4 + level of the substrates decreased as the amount of PBH or perlite was increased. The levels of NO3 and NH4 + were within acceptable ranges for unused substrates. Substrate P and K increased as the amount of PBH in the substrate was increased, but the concentration of P and K remained unchanged or decreased as the amount of perlite was increased. None of the differences between equivalent PBH and perlite-containing substrates was high enough to be problematic with respect to crop production and all of the chemical parameters were within acceptable ranges for unused root substrates.

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Substrates were formulated by blending parboiled fresh rice (Oryza sativa) hulls (PBH) or perlite with sphagnum peat (peat) to produce root substrates (substrates) that contained 20%, 30%, 40%, 50%, or 60% (by volume) PBH or perlite with the remainder being peat. After 0, 4, or 8 weeks in a greenhouse environment, samples were taken and calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B) were determined. At all sampling times, substrates containing PBH had higher Ca concentrations than perlite-containing substrates. At all sampling times, Ca concentration decreased as the amount of perlite or PBH was increased, but the Ca concentration decreased at a higher rate in perlite-containing substrates than in PBH-containing substrates. After 0 weeks, perlite-containing substrates had higher Mg concentrations than equivalent PBH-containing substrates, but the opposite was true after 4 weeks. After 8 weeks, perlite- and PBH-containing substrates had similar concentrations of Mg. At all times, Mg concentration decreased as the amount of perlite or PBH was increased. Perlite substrates had higher concentrations of Fe than equivalent PBH substrates, and as the amount of perlite or PBH was increased, the amount of Fe decreased. PBH-containing substrates had higher concentrations of Mn than equivalent perlite-containing substrates, and as the amount of PBH was increased, the amount of Mn increased. Cu concentrations were significantly affected by sampling time, but at all sampling times, PBH-containing substrates had similar or higher Cu concentrations than equivalent perlite-containing substrates. Perlite substrates had higher concentrations of Zn than equivalent PBH substrates, and as the amount of perlite was increased, the amount of Zn increased. S and B were not significantly affected by substrate component or time. Secondary macro- and microelement concentrations of all substrates were within recommended levels for greenhouse crops except for Mn. Mn concentrations were within recommended ranges at up to 50% PBH. In most cases, PBH would be used at levels lower than 50%, but in cases where more than 50% PBH were used in the substrate, proper pH management may be important to prevent excessive Mn availability.

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The physical properties of new 15.2-cm plastic and comparably sized bioplastic, solid ricehull, slotted ricehull, paper, peat, dairy manure, wood fiber, rice straw, and coconut fiber containers were determined. Additionally, the physical properties of these containers were determined after being used to grow ‘Rainier Purple’ cyclamen (Cyclamen persicum L.) in ebb-and-flood benches for 15 weeks in a greenhouse environment. The punch strength of new coconut fiber containers was the highest of the containers. The used plastic containers had strengths of 228.0, 230.5, and 215.2 N for the bottom, middle, and top zones, respectively. The used peat, dairy manure, and wood fiber containers had strengths of less than 15 N for each zone. Tensile strength of all new containers was 10 kg. The plastic, bioplastic, solid ricehull, slotted ricehull, paper, and coconut fiber containers had used strengths that were similar to plastic containers. Total water used for wood fiber containers was higher than plastic containers. Irrigation intervals for plastic containers were similar to bioplastic, solid ricehull, slotted ricehull, paper, and coconut fiber containers. The irrigation interval for plastic containers was 1.32 days and the wood fiber container had the shortest irrigation interval at 0.61 day. Container absorption for coconut fiber containers was 255 mL and was higher than plastic containers. Wood fiber container absorption was 141 mL and lower than plastic containers. Plastic, bioplastic, solid ricehull, and slotted ricehull containers had no visible algal or fungal growth. The wood fiber containers had 79% of the container walls covered with algae or fungi and the bottom and middle zones had 100% algae or fungi coverage. The bottom zone of rice straw, dairy manure, and peat containers also had 100% algae or fungi coverage. The bioplastic, solid ricehull, and slotted ricehull containers in this study proved to be good substitutes for plastic containers. These containers retained high levels of punch and tensile strength, had no algal and fungal growth, and required a similar amount of solution as the plastic containers to grow a cyclamen crop. The peat, dairy manure, wood fiber, and rice straw containers proved not to be appropriate substitutes for plastic containers because of the low used strengths, high percentage of algal and fungal coverage, and shorter irrigation intervals as compared with plastic containers.

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