Physical Properties of Ground Parboiled Fresh Rice Hulls Used as a Horticultural Root Substrate

Buck, Johann S.; Evans, Michael R.

doi:10.21273/hortsci.45.4.643

Cited by 23 publications

(14 citation statements)

References 26 publications

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“…A third ground rice hull product (RH3) was a commercially available ground PBH material (Riceland Foods) that was ground in a hammer mill until it passed through a screen with 1.18-mmdiameter openings and was collected on a screen with 0.18-mm openings. These grades of ground PBH were used because they had been previously shown to have physical properties within recommended ranges for use as a substrate (Buck and Evans, 2010).…”

Section: Methodsmentioning

confidence: 99%

“…No fresh ground rice hull products passed through 1-, 2-, 4-, or 6-mm-diameter screens had the same physical properties as peat, but some of the products had physical properties within recommended ranges. Buck and Evans (2010) reported that ground PBH passed through a 1.18-mm screen and collected on a 0.18-mm screen had a similar total pore space, air-filled pore space, and water-holding capacity as a sphagnum peat. Several other ground rice hull products, although different from the sphagnum peat, had physical properties that were within acceptable ranges for substrate components.…”

mentioning

confidence: 99%

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The pH, Electrical Conductivity, and Primary Macronutrient Concentration of Sphagnum Peat and Ground Parboiled Fresh Rice Hull Substrates Over Time in a Greenhouse Environment

Evans

Buck

Sambo

2011

hortte

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The primary objective of this research was to compare the pH, electrical conductivity (EC), and primary macronutrient status of three ground parboiled fresh rice hull (PBH) products to sphagnum peat when used as a root substrate over 56 days in a greenhouse environment. The three grades of ground rice hull products were produced by grinding PBH and passing the ground product through different screens. One grade (P3) was passed through a 2.00-mm screen and captured on a 1.00-mm screen. The second grade (P4) was passed through a 1.00-mm screen and captured on 0.50-mm screen. A third ground rice hull product (RH3) was a commercially available, ground PBH material that was ground in a hammer mill until it passed through a screen with 1.18-mm-diameter openings and was collected on a screen with 0.18-mm openings. The pH of sphagnum peat ranged from 3.4 to 3.7 across time. The pH of RH3 and P3 increased from 4.7 to 7.1 on day 5 and 14, respectively, before decreasing to 6.3 and 6.7, respectively, on day 56. The pH of P4 increased from 4.8 to 6.9 on day 6 before decreasing to 6.6 on day 56. The P4 had an EC of 1.2 dS·m−1, which was higher than that of peat, RH3, and P3, which had similar EC of 0.7 to 0.8 dS·m−1 regardless of time. The ammonium (NH4+) concentration was unaffected by time. Peat had an NH4+ concentration of 6.4 mg·L−1, which was lower than that of the ground rice hull products. The P3 had an NH4+ concentration of 14.6 mg·L−1, which was higher than that of RH3 and P4. The RH3 and P4 had similar NH4+ concentrations of 11.8 and 10.8 mg·L−1, respectively. The nitrate (NO3−) concentration was unaffected by time. The RH3 had a NO3− concentration of 8.2 mg·L−1, which was significantly higher than that of peat, P3, and P4, which had similar NO3− concentrations of 0.5 mg·L−1. The phosphorus (P) concentration in peat ranged from 1.3 to 2.5 mg·L−1 across the sampling times, and peat had a lower P concentration than all rice hull products, which ranged from 57.4 to 104.4 mg·L−1. The potassium (K) concentration in peat ranged from 2 to 5 mg·L−1 across the sampling times and was always lower than that of the rice hull products, which had a K concentration ranging from 195 to 394 mg·L−1. Because pH, P, and K concentrations were above recommended concentrations, ground rice hull products would not be suitable as a stand-alone substrate but might be amended with materials such as elemental sulfur or iron sulfate to adjust the pH or blended with other components to reduce the P and K concentrations to within recommended concentrations.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

The pH, Electrical Conductivity, and Primary Macronutrient Concentration of Sphagnum Peat and Ground Parboiled Fresh Rice Hull Substrates Over Time in a Greenhouse Environment

Evans

Buck

Sambo

2011

hortte

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“…1). The physical properties of substrates have been reported to be largely determined by the size of the particles of the substrate components (Buck and Evans, 2010). Larger particles tend to result in the creation of larger pores (macropores) in substrates.…”

Section: Resultsmentioning

confidence: 99%

Efficacy of Cork Granulates as a Top Coat Substrate Component for Seed Germination as Compared to Vermiculite

Bozzolo

Evans

2013

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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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“…Potential alternatives include coconut (Cocos nucifera L.) fibers (coir), composts, rice (Oryza sativa L.) hulls, wood chips, biochar, and others (Abad et al, 2002;Alvarez et al, 2017;Buck and Evans, 2010;Barrett et al, 2016;Margenot et al, 2018;Massa et al, 2018;Suo et al, 2013;Xiong et al, 2017). For example, Buck and Evans (2010) and Sambo et al (2008) found that rice hulls have properties similar to those of peat. Xiong et al (2017) found that coir, compared to peat, may produce plants of similar size and quality.…”

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Using Processed Corn Stover as an Alternative to Peat

Ruis¹,

Blanco‐Canqui²,

Paparozzi³

et al. 2019

horts

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Processed corn (Zea mays L.) stover (PCS), defined as finely ground stover with or without additions, could be a potential alternative to peat in greenhouse mixes. However, this option has not yet been examined. We performed two split-plot experiments (1 and 2) with tomatoes (Solanum lycopersicum L.) and marigolds (Tagetes patula L.) as main plots. Expt. 1 involved five stover rates (0%, 25%, 50%, 75%, and 100% by volume) mixed with peat as subplots. Expt. 2 involved 0% stover mixed with peat, 25% distillers grain, and 50% quick compost (mechanically processed to accelerate compost process) stover with and without CaO, and 75% quick compost stover without CaO, as subplots. We measured growth parameters (height, dry weight, and flower number) and properties of the mixes. During Expt. 1, across both species, the addition of stover at rates >50% reduced relative greenness by 40%, vegetative biomass yield by 74%, and reproductive biomass yield by 73% compared to mixes with 0% and 25% stover. As the stover rate increased, available water content in the mixes decreased (r = −0.34; P < 0.001). Mixes with 0% and 25% stover had 34% more available water than mixes with 100% stover, which probably reduced plant growth in the 100% stover treatment. As the stover rate increased, plant tissue N and P concentrations decreased. Mixes with 0% stover generally had greater N and P concentrations than mixes with stover. During Expt. 2, for marigolds, the addition of 50% quick compost stover+CaO and 75% quick compost stover-CaO reduced relative greenness by 19% and vegetative biomass by 66% compared to mixes with 25% distillers grain or 0% stover. For tomatoes, the addition of 50% quick compost stover+CaO and 75% quick compost stover-CaO reduced biomass yield by 64%, which may be due to the higher pH and electrical conductivity (EC) of both treatments. Plant tissue N and P concentrations were greater in the mix with 25% distillers grain compared to most treatments, but N and P concentrations in the other mixes varied. Overall, the 25% distillers grain (3 peat: 1 distiller grain: 4 perlite) and 25% stover (3 peat: 1 stover: 4 perlite) treatments showed the most promise as additives in a peat-based mix.

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Physical Properties of Ground Parboiled Fresh Rice Hulls Used as a Horticultural Root Substrate

Cited by 23 publications

References 26 publications

The pH, Electrical Conductivity, and Primary Macronutrient Concentration of Sphagnum Peat and Ground Parboiled Fresh Rice Hull Substrates Over Time in a Greenhouse Environment

The pH, Electrical Conductivity, and Primary Macronutrient Concentration of Sphagnum Peat and Ground Parboiled Fresh Rice Hull Substrates Over Time in a Greenhouse Environment

Efficacy of Cork Granulates as a Top Coat Substrate Component for Seed Germination as Compared to Vermiculite

Using Processed Corn Stover as an Alternative to Peat

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