Source: UNIVERSITY OF ARKANSAS submitted to
EDAPHICS OF HORTICULTURAL SUBSTRATES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0190809
Grant No.
(N/A)
Project No.
ARK01937
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2007
Project End Date
Sep 30, 2012
Grant Year
(N/A)
Project Director
Evans, M.
Recipient Organization
UNIVERSITY OF ARKANSAS
(N/A)
FAYETTEVILLE,AR 72703
Performing Department
Horticulture
Non Technical Summary
Research is needed to create value-added product from agricultural by-products. This project will continue to evaluate agricultural by-products as a means of creating horticultural substrates for use in the horticultural industry.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020110116010%
1022129116015%
1024020116010%
2120110116010%
2122129116010%
2124020116010%
5110110116015%
5112129116010%
5114020116010%
Goals / Objectives
Within this project are four major research objectives. These are: 1) the development and evaluation of ground fresh rice hulls as a horticultural substrate component, 2)development of co-composts of rice hulls and pine bark as a horticultural substrate component, 3)evaluation of aerated waste glass (earthstone) as an alternative to perlite for use in horticultural substrates, and 4) evaluation of silicates for use as a substrate amendment to increase disease suppressiveness of horticultural substrates.
Project Methods
1. The development and evaluation of ground rice hulls as a horticultural substrate component: Substrates will be formulated by blending ground rice hulls, horticultural perlite [4-6mm (0.15-0.23 inch)], 3/8 inch composted bark and sphagnum peat (pH adjusted using calcitic limestone to a pH of 5.4) at varying proportions. All substrates will contain either 20% (v/v) perlite or composted bark and 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80% (v/v) ground rice hulls with the remainder being sphagnum peat. 2. Development of co-composts of rice hulls and pine bark as a horticultural substrate component: A system for composting fresh rice hulls and co-composting fresh rice hulls with pine bark will be developed. In the first phase of the research different compost mixtures and different nitrogen concentrations will be tested. The compost treatment combinations will include: 100% fresh rice hulls, 100% bark, 25% fresh rice hulls + 75% bark, 50% fresh rice hulls + 50% bark, and 75% fresh rice hulls + 25% bark. 3. Evaluation of aerated waste glass (earthstone) as an alternative to perlite for use in horticultural substrates: Basic physical properties of Earthstone and Earthstone-containing substrates will be determined as well as water release characteristics and water loss (dry down) rates. We will also determine chemical properties of Earthstone and chemical properties of root substrates containing Earthstone as compared to perlite and PBH-containing substrates. Plant production trials using peat-based substrates with Earthstone, perlite, PBH and bark will be conducted to determine usability as an alternative to perlite. 4. Evaluation of silicates for use as a substrate amendment: We will determine efficacy of potassium silicate for inhibiting soil-borne fungal pathogens causing post-transplant root and stem rot of greenhouse crops. Will also determine efficacy of incorporation of silica in the mineral nutrition regime to inhibit soil-born fungal pathogens causing post-transplant root and stem rot of greenhouse crops. Effect of silicates on pH of peat-based root substrates over time will also be tested.

Progress 10/01/07 to 09/30/12

Outputs
OUTPUTS: The results of this research were disseminated as oral and poster presentations at the annual meetings of the American Society of Horticultural Science in 2009 (St. Louis, MO), the International Society for Horticultural Science in 2010 (Lisbon, Portugal), the International Symposium on Organic Matter in Horticulture in 2011(Adelaide, Australia), and the International Substrates Symposium in 2011(Barcelona, Spain). Results were reported in referred manuscripts published in HortScience, HortTechnology and ActaHorticulturae. Results were also presented at various industry meetings. PARTICIPANTS: Dr. Michael R. Evans. Professor. Department of Horticulture. University of Arkansas. Johann Buck. Graduate Research Assistant. Department of Horticulture. University of Arkansas. Elmer Salazar. Graduate Research Assistant. Department of Horticulture. University of Arkansas. Clint Metcalf. Graduate Research Assistant. Department of Horticulture. University of Arkansas. Bernard Krumpelman. Program Technician. Department of Horticulture. University of Arkansas. Qingfang Chen. Program Technician. Department of Horticulture. University of Arkansas. TARGET AUDIENCES: The primary audience for this research was companies involved in the production of ornamental and food crops in greenhouse or other controlled environments. A secondary audience was companies involved in the production of substrates and fertilizers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
This research provided value-added product opportunities for agricultural waste products and provided lower cost substrate locally available components to the greenhouse and nursery industries. These findings allowed growers to become more sustainable in their production practices. Resources provided supported graduate research assistants and a program technician to conduct the described research. Research was conducted on four major agricultural byproducts including parboiled whole fresh rice hulls (PBH), ground fresh rice hulls (GRH), dairy biofiber (DBF) and granulated cork. Fresh rice hulls ground in a hammer mill and screened through a 1.18-mm screen and collected on a 0.18-mm screen (RH3) and particles with a specific diameter of 0.5 to 1.0 mm had total pore space (TPS), air-filled pore space (AFP) and water-holding capacity similar to that of Canadian sphagnum peat (peat). However, RH3 had more available water (AVW), a higher bulk density (BD) and a higher particle density (PD) than peat. When blended with 20% to 40% perlite or 1-cm aged pine bark, RH3-based substrates had lower TPS, similar AFP and lower WHC than equivalent peat-based substrates. The RH3-containing substrates had higher BD and average PD than equivalent peat-based substrates. Overall, peat-based substrates in which up to 40% of the peat was replaced with RH3 had physical properties that, although different from peat controls, were within commonly recommended ranges for substrates used to grow greenhouse crops. Dairy biofiber (DBF) had physical and chemical properties within acceptable ranges for use as a substrate component except for the pH which varied depending on source but was always above the recommended pH in all cases. Plants grown in peat-based substrates with up to 30% DBF were found to be similar to those grown in a peat and perlite substrate and were of a marketable quality. Granulated cork was evaluated as a top coat substrate for seed germination. Cork granulates had a bulk density of 0.16 g/cc, an air-filled pore space of 22.7 % and a water-holding capacity of 35.1 %. For tomato, impatiens, and vinca days to germination were similar between seed germinated using vermiculite and granulated cork as a top coat. Days to germination of geranium and pepper were significantly different with geranium and pepper seed 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 seed germinating per plug tray was similar between the top coats. Number of seed germinating per tray for pepper and vinca were significantly different. Pepper had an average of 2.8 more seed germinating per tray, and vinca had an average of 2.4 more seed germinating per tray if seed were germinated using granulated cork versus vermiculite. For all species, dry shoot and dry root weights were similar for seedlings germinated using cork and vermiculite top coats.

Publications

  • Bozzolo, Arianna and Michael R. Evans. 2013. Efficacy of cork granulates as a top coat substrate component for seed germination as compared to vermiculite. HortTechnology (In Press).
  • Bassan, A., P. Sambo, G. Zanin and M.R. Evans. 2012. Use of fresh rice hulls and anerobic digestion residues as substrates alternative to peat. Acta Horticulturae 927:1003-1010.
  • Bozzolo, A. G. Ponchia and M.R. Evans. 2012. Germination and growth of seedlings in peat-based substrates processed dairy manure solids. Acta Horticulturae 937:31-36.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: The results of this research were disseminated to the scientific and trade communities through research manuscripts published in HortTechnology and HortScience. The results were also disseminated at presentations made at International Society for Horticultural Science meetings in Adelaide, Australia and Barcelona, Spain. PARTICIPANTS: In addition to Dr. Michael Evans (University of Arkansas, Fayetteville, AR), participants in research projects included Dr. Paolo Sambo and Dr. Paolo Zanin (University of Padova, Legnaro, Italy) and Dr. Todd Cavins (Sun Gro Horticulture, Bellvue, WA). TARGET AUDIENCES: The target audience for this research was profession greenhouse and nursery operations as well as allied supporting companies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
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 electrical conductivity (EC) of 1.2 dS/m which was higher than that of peat, RH3 and P3 which had similar EC of 0.7 to 0.8 dS/.m regardless of time. The ammonium concentration was not affected by time. Peat had an ammonium concentration of 6.4 mg/L which was lower than that of the ground rice hull products. The P3 had an ammonium concentration of 14.6 mg/L 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, respectively. The nitrate concentration was not affected by time. The RH3 had a nitrate concentration of 8.2 mg/L which was significantly higher than that of peat, P3 and P4 which had similar nitrate concentrations of 0.5 mg/L. The phosphorus concentration in peat ranged from 1.3 to 2.5 mg/L across the sampling times, and peat had a lower phosphorus concentration than all rice hull products which ranged from 57.4 to 104.4 mg/L. The potassium concentration in peat ranged from 2 to 5 mg/L across the sampling times, and was always lower than that of the rice hull products which had a potassium concentration ranging from 195 to 394 mg/L. Growstones made from recycled glass had a total pore space of 87.4% (by vol.) 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 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/cc 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 equivalent PBH-containing substrates. Substrates containing 20% or more GS had a higher WHC than equivalent perlite- or PBH-containing substrates.

Publications

  • Zanin, G., A. Bassan, P. Sambo and M.R. Evans. 2011. Rice hulls and peat replacement in substrates for vegetable transplant production. Acta Horticulturae 893:963-970.
  • Kuehny, J., M. Taylor and M.R. Evans. 2011. Greenhouse and landscape performance of bedding plants in biocontainers. HortTechnology 21(2):155-162.
  • Evans, Michael R., P. Zanin and T. Cavins. 2011. E-values generated from dry-down models as a physical property measurement for evaluating and classifying wetness of root substrates. HortScience 46(4):627-631.
  • Evans, Michael R., J. Buck and P. Sambo. 2011. The pH, electrical conductivity, and primary macronutrient concentration of sphagnum peat and ground parboiled fresh rice hull substrates over time in a greenhouse environment. HortTechnology 21(1)103-108.
  • Evans, Michael R. 2011. Physical properties of and plant growth in peat-based root substrates containing glass-based aggregate, perlite and parboiled fresh rice hulls. HortTechnology 21(1):1-5.


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: The results of this research were disseminated to the scientific and trade communities through research abstracts and presentations at the Annual Meeting of International Society for Horticultural Science (Lisbon, Portugal, 2010). The results were also disseminated to the horticulture industry through publications in trade journals (GMPro Magazine) and national trade meetings (Ohio International Short Course). PARTICIPANTS: In addition to Dr. Michael Evans (University of Arkansas, Fayetteville, AR), participants in research projects included Dr. Paolo Sambo (University of Padova, Legnaro, Italy), Dr. Matt Taylor (Longwood Gardens, Kennett Square, PA) and Dr. Jeff Kuehny (Louisiana State University, Baton Rouge, LA). TARGET AUDIENCES: The target audience for this research was profession greenhouse and nursery operations as well as allied supporting companies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Water use, dry strength, wet strength, algal/fungal growth and decomposition were evaluated for eight biocontainers compared to traditional petroleum-based plastic containers when used to grow long-term greenhouse crops using subirrigation systems. Physical properties varied significantly among the different types of containers. In particular, Cowpot, peat and Fertil biocontainers were found to have low wet strength and tended to break apart before the crop was marketable. Peat, straw, cocofiber and Fertil biocontainers required significantly more water to grow a crop to a marketable stage than other biocontainers as well as traditional petroleum-based plastics. ricehull and OP47 biocontainers had physical properties similar to traditional petroleum-based plastic containers. The information generated from this research will allow manufacturers improve biocontainer properties and will allow greenhouse and nursery managers to make decisions regarding which biocontainer(s) would be most suitable for their operations. Ultimately, the results of this research will help to reduce the use of petroleum-based plastics in greenhouse and nurseries and reduce waste plastics. In another area of research, the physical and chemical properties of dairy biofiber and dairybiofiber-containing root substrates where evaluated and compared to standard substrates composed of peat. Diary biofiber had physical and chemical properties within acceptable ranges except for having a high pH. When blended into peat-based substrates at rates of up to 30% dairy biofiber, the substrates had suitable physical and chemical properties. Therefore, dairy biofiber could be used as a partial alternative to peat in root substrates. Greenhouse-based plant production trials were performed and crops grown in substrates containing up to 30% dairy biofiber were of similar quality crops grown in 100% peat-based root substrates. The results of this research demonstrate that dairy biofiber could be used as an effective partial replacement for peat. This could result in a decreased reliance on peat and an increased use of processed animal manures as root substrate components. Ground waste cork was evaluated for its potential as a top coat for germination of seedlings. Germination and seedling growth were similar for seed of various species of plant germinated using ground cork and vermiculite as germination top coats.

Publications

  • Evans, Michael R., Matt Taylor and Jeff Kuehny. 2010. Physical properties of biocontainers for greenhouse crops production. HortTechnology 20(3):549-555.
  • Buck, Johann and Michael R. Evans. 2010. Physical properties of ground parboiled fresh rice hulls used as a horticultural root substrate. HortScience 45(4):643-649.
  • Sambo, P., A. Bassan, and M.R. Evans. 2010. Use of fresh rice hulls and anerobic digestion residues as growing media alternative to peat. Proceedings of the International Society for Horticultural Science. Lisbon, Portugal. Abst. Sm04.007.
  • Bozzolo, A., M. Evans, and G. Ponchia. 2010. Germination and growth of seedlings in peat-based substrates amended with Nature's Natural Dairy Manure Product. Proceedings of the International Society for Horticultural Science. Lisbon, Portugal. Abst. S09.317.
  • Taylor, M., M. Evans, and J. Kuehny. 2010. The Beef on biocontainers: strength, water use, biodegradability and greenhouse performance. The OFA Bulletin. Sept/Oct. 923:1, 5-9.
  • Taylor, M., M. Evans, and J. Kuehny. 2010. Comparing strength and biodegradability of biocontainers. Greenhouse Management and Production (GMPro). September. pp. 14-20.


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: The results of this research were disseminated to the scientific and trade communities through research abstracts and presentations at the Annual Meeting of American Society for Horticultural Science (St. Louis, MO, 2009). The results were also disseminated to the horticulture industry through publications in trade journals (GMPro Magazine) and national trade meetings (Ohio International Short Course). PARTICIPANTS: In addition to Dr. Michael Evans (University of Arkansas, Fayetteville, AR), participants in research projects included Dr. Paolo Sambo (University of Padova, Legnaro, Italy), Dr. Matt Taylor (Longwood Gardens, Kennett Square, PA) and Dr. Jeff Kuehny (Louisiana State University, Baton Rouge, LA). TARGET AUDIENCES: The target audience for this research was profession greenhouse and nursery operations as well as allied supporting companies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The physical properties of water use, dry strength, wet strength, algal/fungal growth and decomposition were evaluated for eight biocontainers compared to traditional petroleum-based plastic containers. Physical properties varied significantly among the different types of containers. In particular, Cowpot, peat and Fertil biocontainers were found to have low wet strength that would be problematic for growers with respect to handling and shipping. Peat, straw, cocofiber and Fertil biocontainers required significantly more water to grow a crop to a marketable stage than other biocontainers as well as traditional petroleum-based plastics. Ricehull and OP47 biocontainers had physical properties similar to traditional petroleum-based plastic containers. The information generated from this research will allow manufacturers improve biocontainer properties and will allow greenhouse and nursery managers to make decisions regarding which biocontainer(s) would be most suitable for their operations. Ultimately, the results of this research will help to reduce the use of petroleum-based plastics in greenhouse and nurseries and reduce waste plastics. In another area of research, the physical and chemical properties of Ecosolve and Ecosolve-containing root substrates where evaluated and compared to standard substrates composed of peat. Ecosolve had physical and chemical properties within acceptable ranges except for having a high pH. When blended into peat-based substrates at rates of up to 30% Ecosolve, the substrates had suitable physical and chemical properties. Therefore, Ecosolve could be used as a partial replacement for peat in root substrates. Greenhouse-based plant production trials were performed and crops grown in substrates containing up to 30% Ecosolve were of similar quality crops grown in 100% peat-based root substrates. The results of this research demonstrate that Ecosove could be used as an effective partial replacement for peat. This could result in a decreased reliance on peat and an increased use of processed animal manures as root substrate components.

Publications

  • Evans, Michael, Jeff Kuehny and Matthew D. Taylor. 2009. Physical properties of biocontainers designed for greenhouse crops production. Hortscience 44(4):1092. Evans, Michael, Clint Metcalf. 2009. Physical properties of Growstones- perlite- and PBH-containing root substrates. HortScience 44(4):1092 Evans, Michael, Donna Graham, Janet C. Cole, Edwin Miller, Richard Harkess, Walter Taylor, Jeff Kuehny and Elizabeth Garrison. 2009. The alliance for cooperative course exchange in the plant sciences. HortScience 44(4):1136. Evans, Michael. 2009. Chemical properties over time of root substrates containing increasing amounts of Growstones, perlite and PBH. HortScience 44(4):1146. Salazar, Elmer Roldan and Michael Evans. 2009. Physical properties of a processed dairy manure product used as a greenhouse root substrate component. HortScience 44(4):1146. Evans, Michael and Clint Metcalf. 2009. Growth of vinca and geranium in Growstones-, perlite- and PBH-containing root substrates. HortScience 44(4):1147. Kuehny, Jeff, Michael Evans and Matthew D. Taylor. 2009. Assessing biodegradable containers for greenhouse and landscape performance. HortScience 44(4):1148. Evans, Michael R., Jeff Kuehny and Matt Taylor. 2009. Biocontainers offer several choices. GMPro Magazine. January. p. 22-24.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Ground parboiled fresh rice hull with an average particle size of 1.0 - 2.0 mm in diameter was used as an alternative to sphagnum peat in greenhouse root substrates. Numerous common greenhouse crops grown in root substrates containing 10% to 40% (v/v) ground rice hull, 40% to 70% sphagnum peat and 20% aggregate (i.e. perlite, PBH or 3/8-inch bark) had similar growth rates, shoot weights and root weights as compared to crops grown in substrates containing 80% sphagnum peat and 20% aggregate. Therefore, up to 40% of the sphagnum peat in the substrate could be replaced with ground parboiled rice hulls with no reduction in crop production or quality. Root substrate aggregates produced from waste glass (marketed as the commercial product Growstones) was evaluated as an alternative to perlite for use in horticultural root substrates. The glass-based aggregate provided for drainage and aeration in the root substrate to a similar degree as horticultural perlite. Root substrates containing the glass-based aggregate had similar chemical properties as root substrates containing similar amounts of perlite except for root substrate pH and silica concentration. Root substrates containing glass-based aggregate had average pH that was 0.5 units higher than equivalent perlite-containing root substrates. Root substrates containing the glass-based aggregate had three times the silica concentration as equivalent perlite-containing root substrates. Annual bedding plants species produced in root substrates containing the glass-based aggregates had similar growth rates, shoot weights and root weights as those grown in perlite-containing root substrates. PARTICIPANTS: Dr. Michael R. Evans, Associate Professor, Department of Horticulture, University of Arkansas. Johann Buck and Elmer Salazar, Graduate Research Assistants, Department of Horticulture, University of Arkansas. Clint Metcalf, Program Technician, Department of Horticulture, University of Arkansas. TARGET AUDIENCES: The primary target audience for this research was companies involved in the production of ornamental and food crops in greenhouses or other controlled environments. A secondary audience was companies involved in the production of substrates and fertilizers. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
This research provides value-added product opportunities for agricultural waste products (i.e. rice hulls, dairy manure, etc.) and provides new sustainable production options to greenhouse and nursery crops producers.

Publications

  • Sambo, P., F. Sannazzaro and M. Evans. 2008. Physical properties of ground fresh rice hulls and sphagnum peat used for greenhouse root substrates. HortTechnology 18(3):384-388.
  • Evans, Michael R. and Mary M. Gachukia. 2008. Secondary macro- and microelements in sphagnum peat-based substrates amended with parboiled fresh rice hulls or perlite. HortTechnology 18(4):650-655.
  • Gachukia, Mary M. and Michael R. Evans. 2008. Root substrate pH, electrical conductivity, and macroelement concentration of sphagnum peat-based substrates amended with parboiled fresh rice hulls or perlite. HortTechnology 18(4):644-649.


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Parboiled fresh rice hulls were ground and separated into various particle size distributions and discrete particle sizes of 2.8, 2.36, 2.00, 1.00, 0.5 and 0.25 mm. The smaller the particle size, the higher the bulk density and water-holding capacity and the lower the air-filled pore space. The smallest particle size (0.05 mm and smaller) reduced wetability and caused the material to pack and become hardened when allowed to dry in a container. The dry hardened material was difficult to re-wet. Vinca, marigold, and geranium plants grown in substrates composed of 20 percent perlite and 80 percent ground rice hulls had lower shoot and root fresh and dry weights than those grown in 20 percent perlite and 80 percent peat root substrates. Replacing the perlite with composted bark or fresh whole parboiled rice hulls did not affect plant growth. Plants grown in root substrates containing 20 percent perlite and up to 40 percent ground rice hulls with the remainder being peat had similar shoot and root fresh and dry weights as plants grown in 20 percent perlite and 80 percent peat root substrates. Vinca seeds were planted in 5 ml plug trays filled with peat amended with 1.6 kg/ft3 calcitic lime (control), 4.5 and 5.6 kg/ft3 potassium silicate alone or combined with 2.3 kg/ft3 calcium sulfate. A peat control drenched with metalaxyl after inoculation was also included. After germination, when the seedlings had one true leaf, half of the treatments were inoculated with Phytophthora nicotianae by applying 500 cfu per cell while the other half remained uninoculated. The percent germination for the potassium silicate combined with calcium sulfate (KSCS) was similar (79 percent) to the control (86 percent) and the metalaxyl treatment (83 percent) whereas the potassium silicate alone had significantly lower germination rates (71 percent). The average dry shoot and root weights for the KSCS treatments were similar to the metalaxyl treatment and the uninoculated control (5.0 and 3.2 mg) but were higher than the potassium silicate treatment alone. The percent mortality due to post-germination damping off for the KSCS treatment was similar (14 percent) to the metalaxyl treatment (9 percent) but was significantly less than the control (86 percent). Impatiens grown in the same silicate substrate treatments suffered 60 percent mortality caused by Rhizoctonia solani without silica while inclusion of potassium silicate reduced mortality to 7 percent which was similar to plants inoculated but treated with PCNB fungicide. Therefore, incorporation of silica into the root substrate significantly reduced the incidence of post-germination damping off of vinca and root/stem rot of impatiens. PARTICIPANTS: Dr. Michael R. Evans. Associate Professor. Department of Horticulture. University of Arkansas. Johann Buck. Graduate Research Assistant. Department of Horticulture. University of Arkansas. Bernard Krumpelman. Program Technician. Department of Horticulture. University of Arkansas. TARGET AUDIENCES: The primary audience for this research was companies involved in the production of ornamental and food crops in greenhouse or other controlled environments. A secondary audience was companies involved in the production of substrates and fertilizers. PROJECT MODIFICATIONS: None

Impacts
This research provides value-added product opportunities for agricultural waste products (i.e. rice hulls) and provides potential alternative disease control strategies (use of silica) for producers of greenhouse crops. Both of these findings will allow growers to become more sustainable in their production practices. Resources provided supported both a graduate research assistant and a program technician to conduct the described research.

Publications

  • Evans, Michael R. and Leisha Vance. 2007. Physical properties of processed poultry feather fiber-containing greenhouse root substrates. HortTechnology 17(3):301-303.
  • Evans, Michael R. and Mary M. Gachukia. 2007. Physical properties of sphagnum peat-based root substrates amended with perlite or parboiled fresh rice hulls. HortTechnology 17(3):312-315.
  • Sambo, P., Sannazzaro, F and M.R. Evans. 200-. Physical Properties of Ground Rice Hulls and Sphagnum Peat Used for Greenhouse Root Substrates. HortTechnology (In Press, April, 2008)


Progress 01/01/06 to 12/31/06

Outputs
Parboiled fresh rice hulls were ground and separated into various particle size distributions and discrete particle sizes of 2.8, 2.36, 2.00, 1.00, 0.5 and 0.25 mm. Particle sizes in the ranges of 0.5 to 1.0 mm and 1.0 to 2.0 mm had physical properties similar to sphagnum peat. A commercially available grade of ground rice hulls (60/80) also had physical properties similar to sphagnum peat. Growth of vinca (Catharanthus roseus), marigold (Tagetes patula), impatiens (Impatiens walleriana) was evaluated in root substrates composed of varying proportions of sphagnum peat, horticultural perlite and the different ground rice hull materials. Growth was reduced when plants were grown in root substrates containing 80% of any of the ground rice hull products and 20% perlite as compared to plants grown in the 80% sphagnum and 20% perlite control root substrate. However, when grown in a root substrate containing up to 50% ground rice hulls, 20% perlite with the remainder being sphagnum peat, growth was similar to plants grown in the sphagnum peat control root substrate. Vinca and impatiens seeds were planted in 5 ml plug trays filled with peat amended with 1.6 kg/ft3 calcitic lime (control), 4.5 and 5.6 kg/ft3 potassium silicate or calcium silicate alone or combined with 2.3 kg/ft3 calcium sulfate. A peat control drenched with Subdue or Banrot after inoculation was also included. After germination, when the seedlings had one true leaf, half of the treatments planted with vinca were inoculated with Phytophthora nicotianae and half of the impatiens were inoculated with Rhizoctonia solani. Half of the cells were uninoculated and served as a control. Inclusion of potassium silicate at 4.5 kg/ft3 suppressed disease development caused by Phytophthora and Rhizoctonia. Inclusion of calcium silicate did not suppress disease development. Vinca and impatiens seeds were planted in 5 ml plug trays filled with peat amended with 1.6 kg/ft3 calcitic lime (control), 2,0 and 4.5 kg/ft3 potassium silicate alone or combined with 2.3 kg/ft3 calcium sulfate. A peat control drenched with fungicides as previously described was included. After germination, when the seedlings had one true leaf, half of the treatments planted with vinca were inoculated with Phytophthora nicotianae and half of the impatiens were inoculated with Rhizoctonia solani. Half of the cells were uninoculated and served as a control. Inclusion of potassium silicate at 4.5 kg/ft3 suppressed disease development caused by Phytophthora and Rhizoctonia. However, disease development on impatiens cause by Rhizoctonia was not suppressed at the 4.5 kg/ft3 rate.

Impacts
This research provides value-added product opportunities for agricultural waste products (i.e. rice hulls) and provides potential alternative disease control strategies (use of potassium silicate).

Publications

  • Evans, M.R. and M.M. Gachukia. 2007. Physical Properties of Sphagnum Peat-based Root Substrates Amended with Perlite or Parboiled Fresh Rice Hulls. HortTechnology (In Press).


Progress 01/01/05 to 12/31/05

Outputs
Parboiled fresh rice hulls were ground and separated into various particle size distributions and discrete particle sizes of 2.8, 2.36, 2.00, 1.00, 0.5 and 0.25 mm. The smaller the particle size, the higher the bulk density and water-holding capacity and the lower the air-filled pore space. The smallest particle size (0.05 mm and smaller) reduced wettability and caused the material to pack and become hardened when allowed to dry in a container. The dry hardened material was difficult to re-wet. Particle sizes in the ranges of 2.36 to 1.00 mm had the best physical properties required for plant growth. Vinca seeds were planted in 5 ml plug trays filled with peat amended with 1.6 kg/ft3 calcitic lime (control), 4.5 and 5.5 kg/ft3 potassium silicate alone or combined with 2.3 kg/ft3 calcium sulfate. A peat control drenched with metalaxyl after inoculation was also included. After germination, when the seedlings had one true leaf, half of the treatments were inoculated with Phytophthora nicotianae by applying 500 cfu per cell while the other half remained uninoculated. The percent germination for the potassium silicate combined with calcium sulfate (FSCS) was similar (79 percent) to the control (86 percent)and the metalaxyl treatment (83 percent) whereas the potassium silicate alone had significantly lower germination rates (71 percent). The average dry shoot and root weights for the KSCS treatments were similar to the metalaxyl treatment and the uninoculated control (5.0 and 3.2 mg) but were higher than the potassium silicate treatment alone. The percent mortality due to post-germination damping off for the KSCS treatment was similar (14 percent) to the metalaxyl treatment (9 percent) but was significantly less than the control (86 percent). Therefore, incorporation of silica into the root substrate significantly reduced the incidence of post-germination damping off of vinca.

Impacts
This research provides value-added product opportunities for agricultural waste products (i.e. rice hulls) and provides potential alternative disease control strategies (use of silica).

Publications

  • No publications reported this period


Progress 01/01/04 to 12/30/04

Outputs
Parboiled fresh rice hulls were ground and separated into different particle sizes and size distributions. The particle sizes of the ground rice hull products could be altered to adjust the physical properties such as water-holding capacity and air-filled pore space. The smaller the particle size, or the smaller the distribution of particle sizes, the higher the water holding capacity. By adjusting particle size, a material was produced that had similar physical properties as Sphagnum peat. Several of the ground materials were successfully used as an alternative to Sphagnum peat in the production of ornamental and vegetable plants in the greenhouse environment. A ground rice hull product was also successfully used to germinate seeds and produce tomato plug transplants. The research with ground rice hulls materials may reduce the need to import and mine from Canada and may create a value-added product using waste rice hulls. Ten common biological agents (i.e. Rootshield, ActinoIron) were evaluated for their effectiveness to inhibit root rot and promote growth in annual bedding plant species. When established plugs were transplanted into growing media containing one of the biological agents tested, neither growth promotion nor disease suppression was observed.

Impacts
This research provides value-added product opportunities for agricultural waste products (i.e. rice hulls and pepper pulp) and provides potential alternative disease control strategies.

Publications

  • Sealy, Ramsey, Michael R. Evans and Craig Rothrock. 200-. Fungicidal properties of a garlic extract in vitro and in peat and sand-based growing media. HortScience. (submitted)
  • Evans, Michael R. and Byron Candole. 200-. Inhibition of Pythium and Phytophthora root rot by coconut coir. HortScience (submitted)


Progress 01/01/03 to 12/31/03

Outputs
Fresh parboiled rice hulls were found to not cause nitrogen tie-up in Sphagnum peat-based substrates and to provide a similar level of drainage and air-filled pore space as perlite when incorporated at rates of up to 20%. At rates above 20%, parboiled fresh rice hull-containing substrates had a higher total pore space and air-filled pore space than equivalent perlite-containing substrates. Therefore, fresh parboiled rice hulls may serve as an effective alternative to perlite. Coconut coir was found to suppress populations of Pythium and Phytophthora and reduce the incidence of damping-off in tomato seedlings caused by these organisms. Sterilization of the coconut coir did not reduce the suppressiveness of the coconut coir and thus the mechanism for suppression appeared to be chemical in nature. Dried waste pepper pulp incorporated into the rooting substrate was also found to be suppressive of several species and Pythium and Phytophthora. However, as rates of the dried pepper pulp exceeded 10% (v/v) growth of the plant material was reduced.

Impacts
This research provides value-added product opportunities for agricultural waste products (i.e. rice hulls and pepper pulp) and provides potential alternative disease control strategies.

Publications

  • Evans, Michael R., B.L. Candole and T.E. Morlock. 200-. Suppression of tomato damping-off caused by Phytophthora nicotianae and Pythium irregulare by dried waste pepper pulp. In review for HortTechnology.
  • Evans, Michael R. and B.L. Candole. 200-. Suppression of Phytophthora and Pythium damping-off of tomato by coconut coir dust. In Review for HortScience.


Progress 01/01/02 to 12/31/02

Outputs
Ornamental seedlings germinated on paper towels treated with humic acids had higher root dry weights than those germinated on towels not treated with humic acids. However, humic acid incorporation into Sphagnum peat-based substrates was found not to significantly affect root growth or stand establishment of ornamental seedlings. Perlite is an expensive component used in artificial growing media. Ground bovine bone was found to not be a potential replacement for perlite. Incorporation of ground bovine bone into Sphagnum peat-based substrates resulted in a significant increase in substrate pH, electrical conductivity and ammonium levels. However, fresh parboiled rice hulls were found to not cause nitrogen tie-up in Sphagnum peat-based substrates and to provide a similar level of drainage and air-filled pore space as perlite. Therefore, fresh parboiled rice hulls may serve as an effective alternative to perlite. Washed, disinfested and ground poultry feather fiber was found to be a suitable alternative to Sphagnum peat. Feather fiber could be incorporated into Sphagnum peat-based substrates at a rate of up to 30% (v/v) without a significant impact on plant growth. Using feather fiber as a substrate component provides a value-added use for waste feathers and allows a reduction in the amount of Sphagnum peat mined from wetlands each year.

Impacts
This research provides value-added product opportunities for two of the major agricultural waste products (poultry feathers and rice hulls) produced by Arkansas agricultural operations.

Publications

  • Evans, Michael R. 200-. Ground Bovine Bone as a Perlite Alternative in Horticultural Substrates. Submitted for publication in HortTechnology.
  • Evans, Michael R. and G. Li. 200-. Effect of Humic Acids on Growth of Annual Ornamental Seedling Plugs. Submitted for publication in HortTechnology.
  • Evans, Michael R. 200-. Processed Poultry Feather Fiber as an Alternative to Peat in Greenhouse Crops Substrates. Submitted for publication in HortTechnolgy.
  • Evans, Michael R. and D.L. Hensley. 200-. Plant Growth in Plastic, Peat and Processed Poultry Feather Growing Containers. Submitted for publication in HortScience.
  • Evans, Michael R. and Douglas Karcher. 200-. Properties of plastic, peat and processed poultry feather fiber growing containers. Submitted for publication in HortScience.