OCAMM Seminar Series

          Click on the title to view summary.  Parenthesis indicate year presented.

Composting: Processes and Systems
In-vessel composting of dairy, poultry and swine manure
Dr. Don Cawthon, Texas A&M - Commerce  (1999)
Issues in composting animal manure
Dr. George Garland, U.S. Environemtnal Protection Agency  (1999)
Proposed composting site at the OARDC Wooster campus
Dr. Ted Short, Gerald Reid, Dr. Harold Keener, Ohio State University (2000)
Managing microbial communities in bioregenerative systems
Dr. Jay Garland, Dynamac Inc., NASA (2000)
Compost education and research in Michigan
Dr. Ted Loudon and Andy Fogiel, Michigan State University (2000)
Composting: Meeting challenges in agriculture and creating opportunities
Dr. Harold Keener, Ohio State University (2001)
Composting as a manure management tool on dairy farms
Dr. John Pecchia, Ohio State University (2001)
Evaluation of an institutional food waste composting and nutrient recycling system
Dr. Sean Clark, Berea College (2002)
More than compost: Daylay Egg Farm overview
Andy Rogowski, Daylay Egg Farm (2002)
GORE cover composting systems: An industry perspective
Oley Sheremata, Sheremata Environmental Consulting (2003)
Development of composting systems for Ohio dairy and hog farms
Dr. Fred Michel, Ohio State University (2003)
Transforming farm residuals into value added products: Composting and alternative technologies
Dr. Robert Rynk, Consultant (2004)
Rain simulation to evaluate leaching from compost windrows
Dr. Harold Keener, Ohio State University (2004)
Composting and anaerobic digestion of manure from antibiotic treated calves
Dr. Osman Atilla Arikan, USDA-ARS (2005)
Penn State's Organics Materials Processing and Education Center
Nadine Davitt, Penn State University
Composting: Utilization
SoilerMaker project: Turning industrial and solid waste products into valuable resources
Dr. Jody Tishmack, Purdue University (2000)
Value-added utilization of composted manures
Dr. Harry Hoitink, Ohio State University (2001)
Mechanisms of biological control of plant diseases with composts
Dr. Harry Hoitink, Ohio State University (2001)
Effects of manure and compost application on soil microbial communities
Dr. Brian McSpadden-Gardner, Ohio State University (2002)
Quality control requirements for value-added marketing of composted manures
Dr. Harry Hoitink, Ohio State University (2002)
Compost teas: Production practices and effects on plant fertility and disease suppression
Dr. Steven Scheuerell, Oregon State University (2004)
Research review of compost used for erosion, sediment and pollution control
Dr. Britt Faucette, Filtrexx International (2006)


In vessel composting of dairy, poultry and swine manure
Dr. Don Cawthon, Texas A & M - Commerce

Three externally-funded projects on rotating-tank in-vessel composting of waste products are currently on-going through the Department of Agricultural Sciences at Texas A&M University-Commerce. These projects are focused on solving specific waste management problems encountered in agriculture and food production and utilization systems as well as searching for value-added uses for the composted products. The projects currently underway include work on dairy cattle solid waste, poultry litter and mortality, and food residuals.  Most of these projects are being supported through Section 319(h) funds authorized through the U.S. Clean Water Act or through funding provided by the Texas Department of Agriculture. The projects typically focus on installation, management and operation of on-site commercial-sized composters for the specific waste streams. Other exploratory projects include development of in-vessel composting techniques for swine manure and mortality, turkey litter and mortality, hatchery waste, fish processing residuals, biosolids, and paper pulp sludge. 


Steve Loerch (OARDC, Animal Sciences) asked Cawthon to explain the characteristics of the continuous flow system.  Cawthon responded that large biosolid (municipal sludge) vessels have 3 compartments separated by trap doors resulting in no mixing between compartments.  However, due to the increased cost of such vessels, the smaller vessels used for livestock manure do not have compartments.  Movement through these vessels is by gravity and some mixing does occur.

Loerch questioned whether the entire unit maintained thermophilic temperatures.  Cawthon replied no, that that the temperature peaked between the middle and the end of the chamber while the coolest temperatures were measured at the loading end.

Harry Hointink (OARDC, Plant Pathology) asked if the percentage of organic matter conversion is measured after the compost is removed from the chamber.  Cawthon said it has not be measured. 

Hoitink commented on the dangers caused if readily digestible organic matter, such as starches, is not decomposed and the compost is used for feed.  Such matter provides a source of nutrients for pathogens, especially Salmonella and Clostridium botulinum.  While these organisms may have been reduced to acceptable levels, large populations may become reestablished if nutrients are available.  Hoitink cited several livestock operations with high death rates after using such feed.  Cawthon replied that because the compost leaving the vessel is not mature, such risks need to be addressed.

Hoitink commented that to be used as a peat moss substitute, it was necessary to know whether the material removed from the chamber is just homogenized without stabilization or is truly composted.  Cawthon noted there is a need for quality control.  Hoitink noted that to meet Federal 503 guidelines for a pathogen reduction, compost must be stabilized by exposing all materials to temperatures of at least 55 degrees Celsius for 3 days.

Fred Michel (OARDC, Food, Agricultural, and Biological Engineering) questioned the economics of the in-vessel system.  Cawthon replied that a system installed for the 400-cow dairy cost $73,000.  These costs included an 8-foot diameter, 24-foot long vessel as well as concrete pads, a separator, and other necessary equipment.  At a market price of $100 per yard, the farmer would realize income of $14,000 per year.  Although this is not a significant source of income, the benefit of successfully managing manure should be considered.

Maurice Watson (OARDC, Natural Resources) asked if the Soil Lite had been analyzed for nutrients.  Cawthon estimated 1 ½ percent for nitrogen and about 3 percent for phosphorus, noting that such analysis is not necessary because Soil Lite is not marketed as a nutritional amendment

Hoitink commented that after 3 to 4 days in a vessel, the compost removed is very immature and would need another 7 to 10 days of composting to be stabilized.  He also commented that if heat drying is the answer to addressing pathogens, producers may ask why bother with composting.

Mike Monnin (National Resource Conservation Service) asked if there are any moving parts within the vessel.  Cawthon replied that there are none.  The only moving part is a chain drive powered by a small electric motor that rotates the chamber 4 revolutions per minute.

Monnin questioned the cost of the in-vessel system at the poultry facility.  Cawthon estimated the cost to be $40,000 to $50,000.  He also emphasized that the vessels are not patented and patents could probably not be obtained for them.

Loerch asked what moisture range was found to be effective.  Cawthon replied that it varies depending on the material being composted.  Dairy manure requires 65 to 70 percent moisture and poultry requires 40 to 45 percent moisture.

Hoitink asked if forced aeration had been studied.  Cawthon answered that is has not as oxygen does not seem to be a limiting factor in these relatively small vessels.

Michel asked if the system was open to the environment.  Cawthon replied that only at the fill end.  This end is covered with a screen plate allowing for ambient ventilation.

Monnin questioned the goal for the C:N ratio of the compost.  Cawthon noted that porosity and moisture content are the greatest challenges.  He also commented that decomposition of “tough” carbons such as wood fiber probably did not occur in the 3 to 4 days the compost is in the vessel.

Michel asked if the temperature of the compost increases after it is removed from the vessel.  Cawthon replied that it varied and that continued composting by static pilot or windrow could be used to address this issue.  He noted that moisture content and time through the vessel may vary with the operator, resulting in variations in stability.

Monnin questioned the possibility of leaving the compost in the vessel for a longer period of time.  Cawthon replied that as the retention time increases, the economics decrease.  Also, once the thermophilic temperature is lost it cannot be reestablished in the vessel due to ventilation.


Issues in composting animal manure
Dr. George Garland, Policy Analyst, U.S. EPA

Increasing interest in manure management at the federal level is leading to increased regulation.  Currently out for comment, the Unified National Strategy for Animal Feeding Operations  (AFO) has been developed by the Federal EPA and USDA under the Clean Water Act.  The Strategy’s focus is to protect water resources by requiring Comprehensive Nutrient Management Plans for livestock operations above a specified number of animal units (not yet determined). Regulations to monitor Total Maximum Daily Loads (TMDLs) on a watershed basis are also being developed.  In addition, the Federal EPA’s focus on food safety as a top priority will impact manure management due to possible contamination from manure pathogens.  Composting of animal manure may play a role in all of these regulations as it has the potential to stabilize nutrients and destroy pathogens.  However, composting faces problems from perceptions by composters and regulators as to what feedstocks are acceptable.


Kevin Elder (ODNR) commented on the need for additional research and documentation of Best Management Practices (BMP’s) for handling animal manure.  There is especially a need to characterize the fate of pathogens.  Garland commented that the concentration of poultry production on the Delmarva Peninsula generates 850,000 tons of manure (per ??) and jeopardizes the Chesapeake Bay watershed.  With little land for spreading, economic means of transporting manure are necessary.  Composting demonstration projects are focusing on reducing the volume/weight and transport costs.

Garland commented that there is a controversy as to whether or not composting binds nutrients, decreasing the risk of runoff.  Maurice Watson (OARDC, Natural Resources) replied that nutrient runoff varies depending on the nutrient, type of manure, manure handling, soils and climate.  Garland noted that another issue under study in the Delmarva Peninsula is the addition of iron to manure to bind phosphorus.

Lynn Willett (OARDC, Animal Sciences) questioned the EPA’s philosophy in establishing a time table as it moves from regulation of industrial waste to regulation of animal waste.  He noted that the lack of uniformity of regulations regarding BMP’s decreases the implementation of the best policies.  Garland replied that the Federal EPA’s role is to establish a national framework which will allow states to be more stringent depending on needs.  The CAFO regulations require Nutrient Management Plans that achieve a given result but there is flexibility in the manure handling methods used to achieve those results.

Elder noted concerns about the way regulations are applied and the costs to the producer and public.  Smaller farms are less regulated but have the potential for environmental impacts.  Garland commented that larger operations may be more responsible because they are more visible.

Elder questioned the need to require permits for smaller farms.  He observed that under Ohio’s current system, infractions by non-permitted operations (usually identified by complaints) are on a case-by-case basis.  Garland noted that without a permit it may be difficult to require compliance.  Elder responded that Ohio has been successful in encouraging voluntary compliance but that the ODNR can go to the courts for non-compliance whether an offender is permitted or not.  Elder also questioned whether increasing the number of producers requiring permits will increase quality.

Harry Hoitink (OARDC, Plant Pathology) noted the need for additional research for producing and applying compost.  Composting for smaller farms is most cost effective if additional buildings or concrete pads do not have to be built.  However, due to Ohio’s climate, this limits composting to late spring through early fall.  Because feedstocks, such as yard trimmings, may be added to manure before composting, additional research is needed to develop a data base on the decomposition of materials as well as the amount and timing for land application.

Hoitink also noted that accurate evaluation of nutrient balances requires that the fertility values of compost be predictable.  A database of fertility values of different composted feedstocks is needed.  Improved technologies, such as gas chromatograph and mass spectometery can be used to determine these values. 

Garland speculated that compost amended soil may be more adaptable to the extremes in rainfall that have been predicted as a result of possible climate change.  Hoitink noted that research presented by Warren Dick (OARDC, Natural Resources) and Ed McCoy (OARDC, Natural Resources) in the early 90’s, documented the build up of organic material in compost amended and non-compost amended soils. 

Watson commented that the build up of organic material is highly variable depending on climate, specifically temperature and precipitation.  In warm, humid climates, decomposition occurs at a faster rate than in a cool climate.  Too much organic matter can be detrimental to crops.  Elder noted that excessive applications of livestock manure (non-composted) have resulted in tie up of available nitrogen resulting in poor crop production.

Elder remarked that current research of the ability of iron or aluminum to tie up phosphorus in soils may allow predictions of how much phosphorus the soil can retain.

Hoitink commented on the need for funding of studies that provide a systems approach to manure management. The National Initiative Competitive Grants program has only funded theoretical studies.  Funding needs to be available for basic research that is combined with applied research.

Bruce Bailey (Kurtz Brothers, Inc.) noted the need for more data on composting of various feedstocks.  According to OEPA regulations, a Class IV composting facility can compost only yard trimmings.  The addition of other feedstocks such as food waste requires a change to a Class II facility thus increasing restrictions and testing requirements, resulting in increased costs.  Garland questioned whether the concerns reflected in this system are legitimate or irrational.

Bailey noted that the system depends on where a material is generated.  While some specific concerns (e.g., meats) may be justified others are not but are treated no differently.  Bailey related that a lettuce leaf discarded during harvesting can be composted in a Class IV facility.  However, if that leaf is discarded during processing it must be composted in a Class II facility or disposed of as solid waste.  The state’s concerns seems to stem from potential liability as hard data is not available.  Garland suggested that conversations with the OEPA and other regulatory agencies could identify what research is needed to eliminate fears and improve the system. 

Bailey noted that part of the problem appears to be the result of differences in opinions between different OEPA departments.  Elder commented that research needs to be in place BEFORE legislation is enacted so that regulations need to reflect science not perceptions.

Fred Michel (OARDC, Food, Agricultural and Biological Engineering) questioned whether the US would follow Canada’s lead in agreeing to reduce greenhouse emissions by 10%.  Garland responded that the US Congress has forbidden any EPA funds to be spent on any research that is related to the Kyoto Accords.

OARDC’s proposed composing site
Dr. Ted Short, Gerald Reid, Dr. Harold Keener, Ohio State University

In 1997, the Wooster campus of the Ohio State University’s (OSU) Ohio Agricultural and Research Development Center (OARDC) reached a crisis when the earthen manure storage pond for dairy manure reached its maximum level.  A Nutrient Management Team was formed to analyze nutrient balances based on a phosphorus standard and to evaluate options for maintaining nutrient balance.  Based on theses analyses, it was determined that the highly liquid dairy manure (85-90% moisture) provided the greatest challenge.  To maintain nutrient balance would require significantly reducing animal numbers or exporting nutrients off campus.  The Team concluded that composting the manure would enhance drying of the manure through biological activity and decrease the volume of material to be exported.

Pilot scale studies indicate that composting manure with approximately 75% moisture is most efficient with continuous aeration.  Currently, manure with a 3 to 1 mixture of dairy and chicken manure is composted in windrows approximately 5 miles east of the dairy facilities.  Aeration is achieved only through turning every 4 to 14 days.  The composting has been successful in decreasing the volume of material by approximately 50% and producing a material that can be spread on OARDC test plots which are not available for raw manure.  The proposed composting site was designed in cooperation with the NRCS, ODNR and OEPA and provides the opportunity to evaluate pad design and runoff treatment as well as composting.  A 30,000 square foot concrete pad will permit continuous aeration and will be used primarily for research.  An adjacent 30,000 square foot earthen pad will be used for research and demonstration as a more cost-effective surface for composting.  Each pad will be drained to a separate series of three wetland cells that will allow treatment of storm water runoff from the pad.


Bill Mitch (OSU) questioned the design parameters used to determine the size of the wetland cells.  Mike Monnin (NRCS) answered that design procedures published by NRCS in 1991 were used.  A maximum biological oxygen demand (BOD) loading of 65# BOD/day was predicted by evaluating the expected BOD of runoff from the pad.  A filter fence down slope of the windrows is expected to remove solid material from the runoff.  The cells were initially designed for a hydraulic retention time of 12 days based on an average rainfall.  However, when accounting for a 25-year storm (4 inches of water in 24 hours), the cells would hold 2 ½ feet of water.  To reduce this depth, Monnin doubled the surface area of the cells which resulted in a BOD loading of 30# BOD/day and a hydraulic retention time of 30 days.  The current design stipulates each cell to be 55 by 27 feet with a total footprint for all six cells of 0.2 acres.

Ted Short (OSU) noted that based on earlier discussions with Tom Price (Price-Barnes Organics), a retention pond was proposed to prevent any release of any runoff.  However, OEPA and NRCS representatives noted that the wetland cells provide treatment of the runoff.   Monnin commented that Price’s composting operation is a different situation as it is close to the Scioto River.

John Smith (OSU) questioned whether winter storms would cause overflow or affect the treatment of the wetlands.  Monnin replied that as long as 6 to 12 inches of water are in the cells going into the winter months there should not be a problem.  However, the treatment will not be as effective during the winter months.  He also noted that the cells are designed for a 25-year storm and are connected by aquadrains that allow control of the water depth within 2-inch increments.  Rick Wilson (OEPA) noted that if the cells are close to overtopping, the drains allow a controlled release to the filter strip rather than a larger overflow.

Warren Dick (OSU) questioned whether the bottom of the wetland cells would be lined with clay or an experimental, synthetic liner.  Monnin responded that the plan is to compact the existing soil.  While this will not provide an impervious barrier, it will provide the required impermeability.  The cells will be lined with 6 inches of hydric soil. Hydric soil can be harvested from ditch cleanings and is favored because it supports wetland vegetation and is permeated by seeds, allowing faster vegetation of the cells.

Mitch suggested that a synthetic liner be considered because a wastewater treatment wetlands should be impervious to protect groundwater. Wilson noted that the wetland design is for storm water runoff on an impervious pad - it will not be used to treat manure or wastewater.  Thus BOD concentrations will be much less than found in domestic wastewater.  The goal of the wetland treatment is to remove nutrients before they reach the filter strip.

Lynn Willett (OSU) questioned the land use beyond the filter strip.  Reid noted that the composting site is surrounded by crop and hay fields.  The filter strip extends approximately 500 feet to where it meets effluent from drain tiles.  Any discharge would eventually drain to an intermittent stream approximately 1 mile (?) down slope.

Rick Stowell (OSU) suggested that Keener describe how the windrows are designed to prevent leachate.  Keener noted that unless rainfall is very heavy, most water falling on a windrow is absorbed.  Aeration of the windrows will increase microbial action that will drive off the water.  Rainfall between the windrows will flow parallel to them, not beneath.

Stowell commented that a swine facility near Wooster treats liquid waste in a wetland.  However, the composting pad runoff will have a significantly reduced BOD as most of the organic matter will remain on the pad.  Wilson that the capture and treatment of storm water flow is a relatively new concept for the OEPA and this site will provide needed research on the effect of such flows on a watershed.

Tom Zimmerman (ATI) questioned whether there would be enough water to support wetland vegetation.  Monnin noted the aquadrain would allow flexibility in controlling water levels.  Also, vegetation such as reeds and cattails can survive drought periods.  Even if only grass is established in the cells, it will be effective for treatment.

Smith questioned the time frame for composting manure and the frequency of turning.  Keener responded that lab experiments indicate 4 weeks are needed.  Reid noted that his current system requires 8 to 10 weeks.  The windrows are turned twice a week for the first few weeks, then once a week, then every other week.  The frequency of turning is determined by monitoring the temperature of the compost.  Keener commented that currently, the windrows are not continuously aerated.  Continuous aeration should reduce the time to 3 to 4 weeks.  Increased throughput is necessary to reduce costs.

Paul Painter (OEPA) questioned the calculation of the 65# BOD/day.  Monnin noted that it was determined using NRCS design criteria.  The estimated flow was based on a weighted average of rainfall through the rainy months (May through July).

Short reported that the proposed composting site was presented to the Ohio Land Improvement Contractors Association (OLICA) and will be used for their educational field day on June 16, 17 and 18.  The field day will include Part 2, Subsurface Drainage Installation, of the Overholt Drainage School 2000.  (Contact Larry Brown at brown.59@osu.edu for more information.)  NRCS, ODNR, OEPA, and others will also collaborate in the field day.  If you are interested in participating in this educational opportunity, contact Mary Wicks (wicks.14@osu.edu).

Wilson noted that the issue of storm water from feedlots and other agricultural uses is coming to the forefront for the Agricultural Engineering Group of the OEPA.  As not much information besides filter strips exists for treating storm water, the OEPA supports this site as an educational and research tool.  (Note:  NRCS calculations for a filter strip with no wetland treatment for the concrete compost pad would require 30,000 square feet which was not feasible.)

Painter questioned if economic studies had been done to determine if the capital costs of investing in composting are offset by the reduction in volume.  With a reduction in volume of approximately 50%, transportation costs should be significantly reduced.  Keener commented that the economics have not been addressed for composting manure.  Preliminary studies of yard waste composting do not apply directly because different materials are used.  For example, sludge composting in Akron and Columbus is estimated to cost $200/lb while yard waste composting is an estimated $10 to 20/cubic yard.  More data on manure composting is needed to evaluate the economics.  One of the goals of this project is to reduce the cost of composting.

Wilson questioned the difference in nutrient value compared to raw manure, e.g., chicken.  Keener noted that 50 to 60% of the nitrogen in chicken manure is lost during composting but other nutrients are not.  Wilson asked if that amount of nitrogen would be lost anyway during field application of raw manure.  Keener agreed.  Approximately, 50% of the nitrogen in raw chicken manure is lost in 1 to 2 days following application.

Stowell observed that composting enhances odor control and incrases acceptability of a livestock operation within a community.  This added value is not found in liquid manure. 

Keener noted that Daylay Egg Farm estimates the cost for composting chicken manure to be $38-40/ton and that they are receiving at least that much in sales. 

Short commented that the extent of composting depends on the use of the product.  For example, some horticultural uses do not want completely finished compost as the microbial activity can suppress disease.

Art Brate (NRCS) asked if there are any plans to monitor flow rates and BOD of the runoff from the pad.  Short responded that it is not currently planned, but the expectation is to collaborate with researchers with expertise in wetlands and other areas.  Brate noted that the data is needed.  Current designs may be overly conservative.  Wilson commented that the information is needed from the earthen pad as it is not clear that all three cells are needed to treat the run off.

Stowell questioned winter maintenance of the wetland.  Monnin replied that with 6 to 12 inches of water going into the winter, plant survival is good.

Short asked about using willows in the wetlands.  Dan Herms (OSU) noted that it depends on the species as their habitats vary.  Monnin stressed staying away from woody plants in the cells as the deep roots affect permeability.  Zimmerman commented that in studies of wetlands used to treat dairy wastewater, that muskrats could be a problem.

Zimmerman noted that with three treatment cells, the third would not have as much water.  In such cases the vegetation may change to grasses, such as canary grass, and sedges that can withstand some flooding.  Wilson agreed and noted the need for more data.

An Overview of a Statewide Education Program and Dairy Manure Composting Research
at Michigan State University

Dr. Ted Loudon and Andrew Fogiel, Michigan State University

Composting research at Michigan State University (MSU) emphasizes on-farm composting as a viable manure management option.  Studies to evaluate the effectiveness of criteria, such as monitoring temperature or carbon dioxide as well as using a compost turner or front-end loader, for turning compost were conducted at the MSU Dairy Teaching and Research Center as well as four dairy farms.  The studies concluded that carbon dioxide monitoring is not a practical criteria for determining when to turn compost.  Also, manure turned by a loader results in a compost of poor quality as indicated by a poor volume reduction and inferior seed germination.  Farmers in these studies continue to compost, citing lack of weed seeds, decreased weight and volume, and improved alfalfa production with the use of compost compared to raw manure.

Ongoing research includes synthetic fleece blankets for covering compost, convective transfer of air through compost, and shredded postage stamps as a carbon source.  Synthetic covers are used during composting to shed water while permitting gas exchange. These coverings can also be effective in retaining heat during the winter but uncovered piles may have increased air circulation during strong winds.  Air circulation may also improve as heating during the composting process can create a “chimney effect.”  This convective air transfer can counteract the anaerobic conditions created by the generation of carbon dioxide during decomposition.  Short-term effects of adding postage stamps as a carbon source may be due to the glucose-based glue being digestible while the laminated paper is not.

In response to a 1995 Michigan law that prohibits the disposal of yard trimmings in landfills, the Michigan Composting Council developed a compost operator-training program.  As a member of the Council, MSU contributed to the program and has been involved in its implementation.  The training program, which includes composting principles, odor reduction, siting and design and daily operations, is geared to leaf/grass composting but also applies to manure.


Harry Hoitink (OSU) questioned the management of the fleece blankets during snow and ice.  Fogiel replied that snow can help the blankets stay in place, as strong winds can be a problem.  Loudon noted that the blanket edges may freeze to the toe of the windrow.  Combining windrows at the start of the cold season so that the blanket remains a few inches above the toe minimizes this problem.  Hoitink suggested that the blankets may be most useful in minimizing evaporation during hot, dry months or for year-round use in warmer climates.

Ted Short (OSU) questioned whether the dairy manure used in composting is separated and if it comes from lactating cows.  Loudon responded that it is from a freestall barn with no separation of liquids.  To reduce the moisture content, a layer of sawdust is added to the alleys in the barn after each day’s scraping and additional sawdust is added at the windrow.  Although concerns that the cows would lie in the alley were expressed, this has not been a problem.  Loudon also noted that sand bedding does not improve the compost, instead it results in decreased aeration.

Steve Loerch (OSU) asked how the manure from the MSU Swine Center is handled.  Loudon described the swine facility as having a slotted floor with a sloped concrete floor below that allows separation of liquids.  The urine runs downslope and is collected in gutters while the feces remain on the floor.  The solids are automatically scraped 4 to 6 times per day and collected for composting.  For swine manure, separation effectively concentrates nutrients with 90 percent of the phosphorus in the solids and 90 percent of the nitrogen in the liquid.

Hoitink questioned the advantage of adding small amounts (5 to 10 percent by volume) of clay during composting.  Loudon responded that the clay changes the character and final appearance of the compost.  Humus will coat the clay particles resulting in a more granular structure to the compost.  Addition of sand to the compost will counteract the effect of the clay.  Clay also increases the oxygen concentration during composting.  Hoitink asked if the nitrogen concentration is affected.  Loudon replied that this has not been studied.

John Smith (?)(OSU) referred to a  Michigan recommendation regarding Johnes disease.  If even one of the animals has Johnes disease, it is recommended that no cattle be grazed on fields spread with raw manure (for one year).   During his presentation, Fogiel suggested that because composting reaches temperatures needed to kill the organism (130 degrees F?), it may provide a solution to the problem.  Smith questioned whether the problem of contamination exists for all cows or only calves.  Fogiel commented on the pathology of the disease.  It can be killed by UV light but must be exposed for six months.  However, calves are more susceptible with mature cows having little risk.

Smith asked how much nitrogen is retained in the compost.  Loudon noted that if the windrow is covered and well managed, approximately 70 percent will be retained.  He also commented on studies at MSU to detect leachate from the piles.  When the windrows are covered, no leachate is detected.  However, if the compost is removed (leaving a small layer from the base) and the windrow is not reestablished, nitrogen leachate forms quickly.

A participant in Wooster questioned whether chemicals applied to leaves and grass cause problems with compost.  Fogiel noted that residual herbicides are not being found in mature compost but that additional research is needed.  Hoitink noted that, as  all herbicides currently in use break down they should not be a problem.

Smith asked if the water in the tank attached to the compost turner is heated and, if not, does it cause unwanted cooling.  This water is used to add moisture to the compost during turning.  Loudon replied that it is at ambient temperature and may cause some evaporative cooling.  Smith commented that he had experienced cold water being added with a hose that reduced the temperature of the compost substantially.  Loudon noted that using a hose probably resulted in uneven mixing creating anaerobic zones which inhibits the composting process.

A participant in Wooster asked about research on the use of forced air to aerate static piles.  Loudon responded that forced air has been studied more extensively than natural flow.  The goal of MSU’s studies of convective air transfer is to improve the feasibility of composting.

Managing microbial communities in bioregenerative systems
Dr. Jay Garland, Dynamac Inc., NASA

A bioregenerative system that permits life support on a long duration (18-20 months) space mission also provides the opportunity to develop a conceptual model for sustainability on Earth.  An extraterrestrial ecosystem must include a closed, small-scale agronomic system and a method for recycling nutrients from crop and human byproducts.  Research at NASA has focused on biological processes for leaching of organic byporducts to provide soluble nutrients for hydroponic plant production.  While minimizing microbial risks presents a challenge, a closed system provides the opportunity to control what enters the system.  Although a decontaminated system was initially favored, current research is focusing on evaluating the functional versatility and richness of microbial communities.  The potential for inclusion of microbes in the system has resulted in the evaluation of composting as an alternative for byproduct management.

Serita (?) asked if the impact of protozoa had been studied in the microbial systems.  Garland responded that baseline characterizations indicate that large rotifer population exists and are important to the population.  However, their functional roles have not been analyzed.

Maurice Watson (OSU) asked if soluble salts were a problem in recycling nutrients.  Salts can be a problem in nurseries.  Garland noted that in recycling gray water, the sodium concentration is very low compared to urine.  For urine, the nitrogen concentration is good, but high sodium levels lead to saturation in 1 to 2 generations.  Reuse of the nutrient water used in hydroponic production did not result in build up.  The mission will require 5 to 6 generations of crops.

Jann Ichida (Ohio Weslyan) questioned the interaction of microorganisms and the influence of antibiotics.  Garland noted that difficulties arise as some organisms are difficult to culture and cannot be used as inoculants.  

Matt Krause (OSU) commented that once a system (e.g., liquids) is stable, the substrate can be used to inoculate a new system.  Garland responded that culturability is used for a general count, allowing a shorter incubation time.  Longer times do not seem to affect the number of cultural types.

Sonia Tiquia (OSU) asked why the number of culturable organisms decreases with time.  Garland noted that it is the nature of organisms.  Using an ecological paradigm, early growth utilizes available nutrients and R-type (?) organisms invade easily and rapidly.  Later, organisms grow more slowly and have more specialized requirements.

Watson asked if “synthetic gravity” is needed for plant growth.  Garland observed that lack of gravity may affect the delivery of nutrients; however, during transit it is expected that stored resources will be used.  Once the mission has landed on Mars (first destination), the reduced gravity (1/3 to ½ of Earth’s) is not expected to be a problem.

Fred Michel (OSU) asked if the agronomic system in the Human Testing System being built at the Johnson Space Center in Houston is a completely closed system.  Garland responded that it is a closed, mechanized system.  He also noted that testing of the system will be phased in, beginning with 100 days and building to 18-20 months.
Krause asked whether a solid matrix is used for is used for plant growth.  Garland replied that it is not used. A nitrogen-nutrient film and wicking material is used at the beginning of the growth cycle as seed initiation is the biggest factor in establishing a plant.  Krause asked why a matrix is not used.  Garland explained that, ideally, no non-consumable materials are used.  Also, since the system is mechanized and does not allow easy access, the nutrient film simplifies the process.

SoilerMaker Project: Turning industrial and solid waste products into a valuable resource
Dr. Jody Tishmack, Purdue University

Begun in 1993, the SoilerMaker Project creates synthetic soil by mixing composted coal ash, tylosin cake and chipped organic material with subsoil.  Difficulties in utilizing the silt-sized coal ash include dust, high pH with the dissolution of lime, and expansion and exothermic reactions with the addition of moisture.  The tylosin is an organic by-product of antibiotic production by Eli Lilly and has a moisture content of 75% giving it a sludge-like consistency.  The chipped organic material consists of yard trimmings, brush, leaves, and pallets.  Research has focused on developing the best mix, determining plant response, and evaluating environmental response.  The benefits of this project include the economic management of by-products, the beneficial reuse of by-products, and the production of a material that can be economically used for land reclamation and conserve natural topoil.

Greenhouse studies using the soil indicate that as little as 25% of the synthetic soil in a soil mix can increase yield.  While no metal uptake or leaching has been detected, high boron concentrations are a concern.  In a pilot study with the Department of Natural Resources (DNR), coal ash, tylosin cake and leaves were mixed and stabilized but not composted and used for reclamation of a coal mining spoils site that had been barren for 25 years.  The mixture was applied in the spring at 50 to 75 tons/acre and tilled into the top 7 inches of soil.  While the plant (grasses) response was good, adjustment of the pH took approximately 1 month, leading to a recommendation for fall application.


Fred Michel (OSU) questioned the concentration of antibiotics in the tylosin cake and whether it was a concern.  Tishmack responded that Eli-Lilly’s tests show the amount is minimal and that it has been land applied in the past, therefore, no additional tests were made.

Lynn Willett (OSU) asked if the material had been tested for environmental contaminants such as dioxin or PCBs.  Tishmack explained that all materials are tested before mixing for the 8 materials regulated under RCRA (Resource Conservation and Recovery Act).  The ash is tested for bulk chemical composition, PCBs and dioxins.  The compost is tested for available nitrogen and bulk nutrients (calcium, sulfur, potassium and phosphorus).

Harry Hoitink (OSU) questioned the sulfur content (not available) of the material added for reclamation.  He noted that in the use of ash and papermill sludges for reclamation of mine spoils, the sulfur content is more important than the pH.  In heavy clay soils with 0.7 – 0.8% sulfur, 100/tons acre of organic material is required.  The organic carbon feeds heterotrophic soil organisms that inhibit the formation of sulfuric acid.  While lime can be added to limit acid formation, too much lime can result in magnesium toxicity.

Tishmack agreed and noted that the DNR study had only looked at the response of materials to see if the mix could be used as a replacement for ag lime and fertilizer.  The DNR customarily uses a cap of  lime to prevent acid migration.   Tishmack clarified that the SoilerMaker Project produces two products:  synthetic topsoil that is a mix of compost and subsoil and an ash-stabilized mix that can replace ag lime and fertilizer.

George ? (Purdue) asked if the 50-75 tons/acre were wet tons and how the composting mix was determined.  Tishmack confirmed that it was wet tons with approximately 35-40% moisture.  The original mixture of 25% ash, 25%cake and 50% chipped organic material was based on the physical properties of the material that allowed for easy handling.  However, as this mixture was low in carbon (the cake has a high nitrogen content), the mix has been changed to 10% ash, 20% cake and 70% chipped organic material plus straw from the veterinary hospital.

Kevin Elder (ODNR) questioned the N-P-K content of the compost.  Tishmack did not have exact figures but noted that the nitrogen in the cake is 10-14% and the compost has a C:N ratio of 14.  The phosphorus and potassium content are not as high as in commercial fertilizers.

Hoitink asked if ash used in roads at the reclamation site is high in potash.  If used in such a large quantity, is there a concern of contamination by the dissolution of potash or other solubles?  Tishmack noted that the phosphorus and potassium levels are not that high based on bulk chemical analysis.  Also, the ground water below the site has been monitored for 6 years and there have been no indications of elevated levels of phosphorus or potassium.

Michel asked how the project deals with leaves only being available in the fall.  Tishmack replied that the stabilized ash mix can be made year round as the ash and tylosin cake is provided regularly and the organic matter is a small percentage.  Composting presents a greater challenge as using fresh leaves affects the C:N ratio and texture of the finished compost.    About 30,000 yards of dried leaves are collected each fall and stored in a pile.  These are utilized in the composting mix.

Tammie Brown? (ODNR) questioned the content of the tylosin food substrate.  Tishmack responded that it is a combination of grains, sugars, salts, corn meal and fishmeal.

Hoitink asked who uses the SoilerMaker products.  Tishmack noted that farmers in Eli Lilly’s land application program receive the stabilized ash product for free and have successfully used it as a soil amendment.  The synthetic soil is sold to the Purdue grounds crew for $10/ton and is successfully used in new gardens and lawns.  The sales, as well as tipping fees for yard trimmings, supports the cost of the project.

Willett questioned the guidelines for metals and toxins.  Tishmack responded that both products are permitted under the Indiana Department of Environmental Management, which requires monthly testing.   Testing of the compost is conducted under the SoilerMaker project and  Eli Lilly is responsible for testing the tylosin cake.  Both follow federal 503 regulations that set guidelines for allowable concentrations of metals.

Willett asked the concentration of boron and regularity of testing for it.  Tishmack explained that the concentration in the compost is 10-15 ppm but drops to 5-9 ppm when blended with topsoil.  Boron is tested periodically although it is not required and is not essential, as grass is less sensitive to high concentrations.

George ? asked if the material is brought to the site and mixed there and whether Tishmack has worked with the turf faculty in research plots at Purdue.  Tishmack noted that mixing of compost and topsoil has been successful both on- and off-site and depends on the project.  To date, only the grounds crew has used the synthetic soil.  They have had a positive response as it minimizes the previous practices of stripping topsoil from farmland and provides a product that has minimal weed seeds.  In a side-by-side comparison, plants were established faster in the synthetic topsoil than in the natural topsoil.

Plans are underway for test plots with the turf research group this year.  Also, Purdue will work with the USDA soil erosion lab this summer to test observations that the synthetic topsoil seems to resist erosion.

Value-added utilization of composted manures
Dr. Harry Hoitink, Ohio State University

Plant loss due to soil-borne plant diseases such Phytophthera root rot has decreased from 75% to 1% in the container industry with the incorporation of biodegradable organic matter into the planting media.  Composted biosolids provide disease-suppressive microorganisms and aged pine bark provides the lignin and lignin-protected cellulose that create an environment in which the organisms can thrive.  Composted biosolids have also been used successfully in the nursery industry.  To effectively suppress disease, compost must reach temperatures that will kill pathogens and have the appropriate chemical (nutrients) and physical factors (drainage, aeration and available water).

Opportunities exist in the container and nursery industries to use livestock manure as a source of biodegradable organic matter.  Wood mulches, which are associated with nitrogen immobilization and fungi, can also benefit from the addition of manure.  Analyses of composted swine manure have similar chemical and physical properties and pilot studies indicate that plant response may improve with additions of 4% to 8% to the planting media. However, high salts from urine and liquid manure systems present challenges for utilizing livestock manure.  Additional research is needed to reduce salt levels in composted manure and to develop “dry” manure management systems or methods for composting high liquid manure.


Warren Dick (OSU) asked what units are used for salt measurements.  Hoitink replied they are in ml/cm with the optimum in a final potting mix being 3 to 4 ml/cm(?).  However, some plants may require lower levels or may tolerate higher levels.  Hoitink noted that some operators in the container industry monitor the conductivity of water leaving the pot to determine fertility needs.

Brian McSpadden-Gardner (OSU) asked if the 18 to 36 hours cited for the first phase of composting in which water-soluble materials decompose is the half-life or complete decomposition.  Hoitink noted that the percentage of water-soluble sugars that decompose during the first 18 to 36 hours depends on the material.  For tree bark, spring cut trees will have a higher sugar content due to sap running.  Food wastes also tend to be high in sugars.  As a result, the first phase of decomposition will be relatively short for these materials.

Ted Short (OSU) asked questioned how compost can be tested for beneficial microorganisms.  Hoitink responded that testing for some specific species is possible but that biocontrol occurs with such a large variety of microorganisms that it is meaningless to count only a few species.  If the compost is sterilized and the correct moisture content and ambient temperature maintained, beneficial microorganisms will re-colonize the compost in approximately two days.  The only way to keep these microorganisms out of the compost is to store it in a sterile, isolated environment.

McSpadden-Gardner asked whether composts are suppressive for larger pathogens.  Hoitink responded that the larger the pathogen, the longer it takes for specific, suppressive microflora to colonize the compost.  This usually occurs within three months but can take over one year.  The chemistry of the material composted will determine the beneficial microorganisms.

Composting:  Meeting challenges in agriculture and creating opportunities
Dr. Harold Keener, Ohio State University

Agricultural enterprises in the 21st century have been challenged to produce high quality food at low cost without impacting the environment or the community.  This is apparent by the new rules and regulations promulgated in recent years, such as free trade agreements, clean water and clear air acts, and the expanding number of lawsuits against farm businesses.  These challenges are leading to innovative concepts in agriculture, many of which center on composting as a way to create value-added “by-product” with multiple marketing opportunities.  Their approaches are addressing the odors, flies and pathogens associated with livestock manures, while closing the loop on nutrient cycling by enabling manure nutrients to be cycled back into the crop production system.


Fred Michel (OSU) questioned whether the poultry manure stored at Rose Acres (Indiana facility with 2.5 million layers, uses high rise house with deep pit with removal after 1 year to covered storage for static pile composting) was utilized in the homeowner market.  Keener responded that he did not know details of markets. Rose Acres has an employee that markets the finished material.

Charlotte Bedet (OSU) asked if the belt system used by Daylay permits compost to reach 55-60 degrees F.  Keener confirmed that it does.  The 3 day belt transport from layer facility to compost building also helps inhibit fly production as the fly life cycle is about 7.

John Smith (OSU) asked if Keener had any experience in composting manure from sand-bedded dairy cows.  Keener replied that he has not worked with sand-laden manure, but has ideas that he expects to research as the composting pad at OARDC becomes fully operational.

Smith asked if Daylay’s composted poultry manure is stabilized.  When water is added, it still smells like manure.  Keener noted that Daylay’s product reaches approximately 2/3 maturity.  Odor issues that occur with land application can be addressed with proper management practices that minimize odors and nitrogen loss.  John Smith suggested disking the compost in during field application.

Smith asked for a description of the pilot vessels used at the OARDC Compost Research Center.  Keener explained that they are 55-gallon drums that are fully insulated to create an environment representative of a windrow.  The vessels allow control and monitoring of the composting process on a small scale.

Robert Hansen (OSU) questioned why dry matter loss can occur with composting dairy manure but with no apparent water loss.  Keener explained that when moisture is greater than 81%, dry matter is lost faster than water.  Although water is lost, its percentage of the total volume may actually increase.  With lower moisture levels, enough heat is created to lose water faster that dry matter.  Keener also noted that without aeration, condensation may occur within the windrow, reducing moisture loss.

Brian McSpadden-Gardner (OSU) asked what size a dairy facility needs to be for composting to be economically feasible.  Keener responded that it depends to some extent on management, especially the amount of liquids generated.  Costs also depend on the distance to transport the manure off-farm and to bring in amendments/bulking agents.

Mike Brugger (OSU) asked whether capturing methane from anaerobic digestion of manure makes sense as energy costs escalate.  Keener noted that Texas A&M, Purdue and others have studied this technology.  In the past, the up front costs for digestion and problems with system maintenance have been issues that needed to be resolved.

Rick Wilson (OEPA) noted that composting can affect nitrogen and phosphorus concentrations.  More land is required for spreading manure if a phosphorus standard is used instead of nitrogen.  Mike Lilburn (OSU) noted that phosphorus is not lost during composting.  Keener responded that with or without composting, the same amount of land is needed to spread the manure for a 600-head herd if the phosphorus standard is used.  However, composting reduces the volume and weight, thus reducing costs to transport off-farm. 

Smith commented that another advantage of compost is that is can be spread closer to homes than raw manure because odor and flies are not issues.

Lilburn reported that current research on phytase feed indicates that less phosphorus is in the feed but because it is in a different chemical form, it is more soluble, thus increasing runoff potential.  Michel asked if soil analyses indicate whether composting decreases the solubility of phosphorus in manures from phytase-fed livestock.  Lilburn noted that with phytase feed, the phosphorus is in an inorganic form which is more water soluble.  Additional research is still needed.

Paul Painter (OEPA) suggested that a sales tax on food could generate funds for grants to farmers to implement manure management practices.  Lilburn noted that a sales tax on septic and sewage treatment plants should also be implemented.

Michel, referring to research on the use of short-paper fiber by-product as an amendment for composting poultry manure, asked how the industries interact.  Keener responded that the Arkansas paper industry provided the original funding for the research.  The short-paper fiber had been landfilled but a change to land application was needed and broiler litter was available.  Current status of the interaction between the two industries is unknown.  Michel asked if the paper industry would be willing to pay for manure.  Keener observed that their motivation seemed to be cost avoidance, but cooperation could be a win-win situation.

Mechanisms of biological control of plant diseases with composts
Dr. Harry Hoitink, Ohio State University

Research data and observations in nurseries have shown that addition of composted organic matter to potting mixes results in suppression of Phytophthora root rots and of some other soil  borne diseases.  The concentration of suppressive microorganisms in compost amended substrates is very high but greatly reduced in “worn out” soils or potting mixes at two years after the amendment.  As a result, predictive disease suppression models have been developed based on the composition and concentration of microbial biomass.  Data is currently being developed to correlate Beta-glucosidase activity with suppressiveness. The concentrations of lignins and of protected cellulose in the substrate predicts suppressiveness.

The effectiveness of composts in suppression of soil borne diseases is dependent on heat kill, organic matter decomposition level (fresh and pyrolized organic material have a negative effect), recolonization of compost by suppressive microorganisms following heat kill, and physical and chemical factors.  Although previous work has focused on soil borne diseases, current research indicates that potting mixes containing composted organic materials which also have been inoculated with Trichoderma hamatum 382can be effective as a biocontrol alternative to foliar fungicides; however, the mechanism of this systemic type of induced resistance is not yet understood.

Although the nursery industry has traditionally relied on aged pine bark and composted biosolids to provide the potential for disease suppression in potting mixes, research indicates that composted animal manures have the potential to replace some of these components but a consistent quantity and quality of these materials will need to be incorporated.  The maturity (stability) of the composted manure and its salinity largely determine its ability to induce suppression.


Dan Herms (OSU) asked for clarification regarding the connection between increased maturity of compost with decreased fungus gnats but decreased disease suppression.  Hoitink noted that compost maturity does seem to solve the fungus gnat problems but that more information must be developed to verify this.

 Hoitink stressed that farmers need inexpensive, practical tools to assess compost stability and such tests also are being developed now.

Jim Skeeles (OSU) suggested that, as the horticultural industry uses composts that are not derived from animal manure, more information is needed about manure composts before it is accepted.  Hoitink replied that nurserymen are aware that manure composts can be effective in disease suppression but need a supply that is consistent in quantity and quality.  However, as high quality bark becomes more difficult to find due to the paper industry harvesting younger trees in which the bark is not as plentiful nor well-developed, manure should become more attractive.  Hoitink noted that to achieve quantity and quality demands, large producers or manure brokers need to start producing quality products. This increasingly is occurring today.

Carl Kipp (Paygro/Garrick, Inc.) commented that composted manure is not well accepted in the nurseries and not at all accepted in greenhouses.  However, with a consistent product and consumer education, these are good potential markets.  Hoitink noted that composted manure has been better accepted on the West Coast as they have been at it longer.

Composting as a manure management tool on dairy farms
Dr. John Pecchia, Ohio State University

The Ohio Water Development Authority has funded OSU researchers to quantify and develop strategies to minimize water usage for widely-used dairy systems in Ohio.  The dairies being evaluated vary in size and manure handling practices, including wet and dry systems.  By decreasing liquids in the manure, the potential risk of environmental contamination and the costs of manure storage and transportation are reduced.

Additional goals of the research are to establish best management practices for composting dairy manure with different bedding materials and to develop value-added products from composted dairy manure.  Current research indicates that differences in bedding material affects the temperature and oxygen, ammonia and nitrate concentrations, during composting as well as the final reduction in volume and C:N ratio.  Additional research will evaluate the effectiveness of forced aeration on the composting process.  Although composting can decrease transportation costs, produce a more stable material and positively impact public perception, challenges include optimizing the process and improving economics.


Fred Michel (OSU) questioned the differences in porosity in composting dairy manure with straw versus sawdust bedding.  Pecchia noted that the porosity for the manure/sawdust material began at 66% and ended at 58% and for the manure/straw material began to 76% and ended at 73%.  The reduction is, in part, due to the reduction in volume.  However, in the beginning, the high water content results in liquid-filled pore spaces, effectively reducing the initial porosity.

Robert Hansen (OSU) noted that the necessity of bringing in bedding material and additional bulking agents for composting increases the cost.  Pecchia agreed and suggested that a liquid manure management system with lagoon storage is less expensive.  However, the environmental risks are greater and storage and transportation costs are higher.  He noted that, as part of the research program, Dr. Hoitink’s (OSU) is evaluating the use of composted dairy manure as a value-added amendment for the potting and nursery industries.

Evaluation of an institutional food-waste composting and nutrient cycling system
Dr. Sean Clark, Berea College

Berea College, a small liberal arts institution in eastern Kentucky, began a food-waste composting program in 1998 to reduce waste and generate a partial or complete substitute for commercial, peat-based, potting mix in its horticultural greenhouse.  Initially the program focused on pre-consumer food waste from the food service kitchen, but later expanded to include post-consumer food waste as well. The per-capita food waste generated as estimated at about 0.4 kg per day.  All food waste was mixed with farm and landscape wastes for composting.  Part of the composting operation was moved into a greenhouse during the winter to supply heat for seed germination and plant production.  The composting system was evaluated economically using the costs of collection, handling, and composting and the value of the finished product in terms of nutrient composition and sufficiency as a partial or complete substitute for commercial potting mix.  Bioassays were used to test the suitability of the compost made from pre-consumer food waste as a partial or complete potting mix with lettuce used as the test crop.  The overall evaluation indicated that the finished compost was suitable as a partial substitute for commercial potting mix and that the composting operation was breaking even financially.  Problems with contamination in the post-consumer food waste collected rendered the finished compost suitable only for field application.  Moreover, an economic analysis indicated that collection and composting of this fraction of the waste was unprofitable.


Dave Elwell (OSU) asked if the compost produced had been compared to other planting media to which nutrients were added.  Clark commented that, as the media was used for organic production, synthetic fertilizers were no longer an option.   The goal was to find an organic source of nutrients, so no comparison was made.

Gonul Kaletunc (OSU) asked if a tipping fees are received. Currently, they are not.  Clark noted that Berea is a city of 12,000 with 1 sewage treatment plant which is currently landfilling the sludge.  He is working on a plan to compost the sludge and use it on the 900 acres not used for organic production.  However, a concrete pad with drainage back to the treatment plant is needed.

Elwell asked what participants in the CSA (Community Supported Agriculture) paid for their produce.  Clark responded that the fee is $250 for the season.  Although this is the low end for CSA’s, there is greater risk to the consumer due to change over in student labor.  Over the past 3 years, Clark found that the cost to consumers is less than non-organic produce purchased in local grocery stores.  In general, certified organic produce commands a 10-20% premium.

Question from Columbus (inaudible).  Clark reported that a pile of material is established in the greenhouse.  After it has heated, it is spread under the table containing the flats with no space between the table and compost.  The compost will continue to heat for 3-4 weeks after which it will be turned again, watered if needed, and left for another 3-4 weeks.  Depending on the temperature of the pile, row fabric may be used to hold in the heat as the compost begins to cool.

Fred Michel (OSU) questioned the feasibility of receiving $140/ton of compost (the figure used in evaluating economics) as yard trimmings compost is usually $30-40/ton.  Clark noted that he researched catalogs and composting facilities outside of Kentucky to find comparable N-P-K analyses.  Many of these sources sell smaller amounts at higher rates.  Although it may be a higher than average price, quality compost is not available nearby, so transport costs must be considered.  Also, potting soil mixes cost close to $100/ton.

Michel asked whether or not there were alternative nutrient sources.  Clark responded that a grass-legume mix is used as a cover crop then disked or plowed in.  Soil fertility is being tracked.  Michel asked if crops other than lettuce and basil are started in flats.  Clark noted that all 40 crops, similar to those found at farmer’s markets, are started in flats.

David Munn (ATI) suggested that if composted sludge is applied to the land, it will not be eligible for organic certification in the future.  Clark noted that the fields that will receive the composted sludge are ½ mile away from the organic fields.  There is no plan to convert the 900 acres to organic production.  Cover crops provide most of the nitrogen, so the compost is needed for phosphorus and potassium.

Munn asked for more information about Berea College’s program to have students work in lieu of tuition.  Clark responded that none of the 1500 students pays tuition but must work at least 10 hours per week for which they receive a low wage.  Some student pay room and board. Most students are from the Appalachian region, Kentucky, W. Virginia, Tennessee and Kentucky, and 1 in 3 applicants are accepted.  There are financial limitations on who can attend with preference given to students who are the first in their family to attend college.  The college is supported through an endowment.

Students can work at a variety of jobs but the farm, including crop and livestock, has the most positions available (~50 with ~10 in the greenhouse and organic field).  Scheduling can be a challenge as students work in 2 hours blocks.

Michel asked if bioaerosols are a problem when shredding and turning compost in the greenhouse?  Are masks required?  Clark noted that most material handling occurs outdoors.  When the smaller amount in the greenhouse is shredded or turned, the building is open and ventilated.  Masks have not been used but will be considered.

More than compost: Daylay Egg Farm review
Andy Rogowski, Daylay Egg Farm

With 2.5 million layers and 600,000 pullets, Daylay Egg Farm utilizes a variety of manure management practices to protect the environment.  Although in recent years more of the manure has been moving off-site, Daylay owns 2,000 acres on which manure is applied.  Switchgrass filter strips are being planted to minimize sediment and nutrient runoff.  Daylay is also working in partnership with several public agencies to restore a stream habitat by adding swithgrass buffers and tree corridors.  Another recent addition is the use of two pivot irrigation systems for disposal of wastewater.  Egg wash and filter backwash water are piped underground from lagoons to the irrigation system and applied at a rate of 0.1 to 0.2 inches.  Daylay is also working with the NRCS and Union SWCD to install a stormwater pond and wetland finishing basin for containment and treatment of runoff from one facility.

Important to Daylay’s manure management is composting of approximately 50% of the manure generated.  The automated system uses belts to remove manure from the layer facility to the composting building over a four-day period.  The use of a low sodium feed to reduce initial moisture and of aeration whisks along the belt results in a decrease of the moisture content from 75% to 50% by the time it reaches the compost building.  Forced aeration of the windrows and frequent, automated turning further reduce the moisture content.  Benefits of the composting system include breaking the fly reproduction cycle, less ammonia loss from the manure, a dry product that is more economical to transport, and a better bird environment.   Daylay holds field days to educate farmers regarding the benefits of using the compost as a fertilizer, including micronutrients, beneficial soil microorganisms and disease suppression.  Daylay is currently transitioning 100 acres to organic and working with a local organic farm to evaluate the impact of the product on yield.


Harry Hoitink (OSU) asked if windrows are aerated along the entire length.  Rogowski clarified that each windrow is aerated approximately ¾ of the length.  An air distribution line is located perpendicular to the windrows where the material is unloaded with T-joints used to distribute air into each lane containing a windrow.

John Pecchia (OSU) questioned the change in temperature along the windrow.  Rogowski noted  that the compost is removed at 70-80 degrees (F).  Mike Monnin (NRCS) asked the high temperature range.  Rogowski noted an average of 130-140 degrees (F), although sometimes higher.

Maurice Watson (OSU) asked the final pH and whether copper is added to the layer’s feed.  Rogowski noted the pH averages 8.  He did not have the feed additive information.

Hoitink asked the moisture content after 40 days.  Rogowski estimated 25-30%.  Hoitink noted that nitrification of the ammonia will occur if the compost is kept wetter for a longer period of time.   The compost can be inoculated with nitrifiers by adding topsoil, but a moisture content greater than 34% is required.

Harold Keener (OSU) noted that a dry product is important in Daylay’s ability to economically transport it to markets but questioned whether dust is an issue during spreading.  Rogowski responded that while some farmers incorporate the compost before planting, the majority apply on top, usually at a rate of 1 ton/acre.  Dust is only a concern near roads as most of it settles within 15 to 20 feet of the spread area.

Hoitink asked if the nitrogen removed by the ammonia scrubber in the composting building will be added to the compost to increase the nitrogen content.  Rogowski noted that the scrubber is not quite operational and the plan is to use the product from it as liquid fertilizer, at least initially.

Watson asked if potassium and calcium are being added to the diet.  If so, it could result in a magnesium deficiency making soil tests essential after application.  Rogowski noted that they supply a large area and farmers usually rotate fields to which compost is applied and most application is based on soil tests.

Effect of manure and compost application on soil microbial communities:
Examples from a transitional vegetable rotation

Dr. Brian McSpadden Gardener, Ohio State University

The impact of adding raw and composted dairy manure on crop, weed, disease, nematode, soil, and microbial variables are being examined in a vegetable rotation that is transitioning to organic production. The addition of two forms of organic amendments differentially affected crop and microbial variables.  Compost additions preferentially impacted plant variables such as crop yield and weed emergence.  Manure additions, with a higher C:N ratio, more profoundly affected soil microbial populations.  Significant increases in the numbers of pseudomonads, including those with biocontrol activity, were observed.  In addition, significant changes in bacterial and fungal communities inhabiting the rhizosphere were detected in the amended plots using DNA-based methods at mid-season.  However, following harvest, only minor differences in soil microbial population structure were observed among the treatments, although some residual effects in microbial biomass N and substrate-induced respiration were also detected.  These results indicate that while the effects of organic amendments may be varied and transient, direct effects on plant growth correlated with nitrogen availability while effects on microbial variables were more greatly affected by carbon availability in the organic amendments.  Nonetheless, differences in plant disease pressure in the tomato plots indicated that compost amendments may contribute to enhanced host resistance.


Harold Keener (OSU) questioned the depth to which the manure and compost were plowed.  McSpadden Gardener replied that it was disked in to a depth of 6 to 8 inches.

Harry Hoitink (OSU) asked if a baseline measure of the microbial population had been made before amendments were added.  McSpadden Gardener noted that the fields had been in clover but otherwise unchanged for the last 2 years.  The clover provided some N which was credited to the plot design and the field may already had some degree of disease suppression but it would have been uniform across treatments.

Hoitink suggested that it is difficult to measure the baseline microbial population.  McSpadden Gardener noted that there is no good absolute measure of microbial biomass or activity and that sample to sample variability can be high with all types of measurements.

Lynn Willett (OSU) asked for a characterization of the manure and compost.  McSpadden Gardener replied that the manure was from the calving barn and had a high sawdust content.  It may have decomposed somewhat in the barn but was not stored outside for long.  The compost was composed primarily of dairy manure with some poultry manure and was 6 months old.  The C:N ratio was 28 for the manure and 14 for the compost. 

Warren Dick (OSU) asked if a single, major pseudomonad (beneficial microbe) peak was generated when a different enzyme was used. (Reference is to analytical procedure, fluorescently-tagged, amplified ribosomal DNA restriction analyses (FT-ARDRA), used to identifying DNA of species present in the rhizosphere).   He noted that, in his experience, it is difficult when using two different enzymes, to get agreement on genera or species.  McSpadden Gardener responded that more than one bacterial species can contribute to a particular signal, such that when a second enzyme is used, the peak areas are not the same.  However, in the data shown, the peaks corresponding to the majority of pseudomonads were of similar size in both the MSPI and RSAI generated profiles.

Fred Michel (OSU) asked if the total DNA content might yield a better measure of total microbial biomass than the summation of peak areas coming from FT-ARDRA signals. McSpadden Gardener noted that with the FT-ARDRA each DNA molecule gets 1 fluorescent tag, thus it measures essentially the same thing.  However, the direct concentration approach may be an easier way to get a measure of the microbial population if there are no PCR amplification artifacts.

Keener questioned the length of the project.  McSpadden Gardener noted that a 4-year rotation would be ideal as 3 years with no chemical inputs is required for organic certification.  However, the research is being funded by a grant which only lasts 2 years.

Hoitink suggested that all crops should be removed to emulate farmers (Note: 70% of the tomato plants were plowed in two weeks after harvest).  McSpadden Gardener responded that due to a lack of equipment and weather conditions, it was more feasible to plow them in.

Hoitink noted that organic farmers typically lose 60 – 70 % of their yield under dry conditions and recommended that, to better evaluate response to nitrogen in amendments, clover not be planted as a cover crop.  McSpadden Gardener responded that the plot is in a transitional phase and that clover or alfalfa are likely to preceed vegetable cropping in an organic production system.

Quality control requirements for value-added marketing of composted manures
Dr. Harry Hoitink, Ohio State University

Composted sewage sludge is used widely by the nursery industry in potting mixes and ground beds to improve soil moisture retention, plant growth and suppress plant diseases. Composted sludges must pass pathogen and heavy metals standards before they can be released to the public. The same federal rules do not apply to sewage sludges applied to land that have not been composted before their application although other regulations govern these byproducts. Negative publicity on sludges in the press typically does not describe these differences in risks associated with composted versus non-composted sewage sludges. As a result, the safety aspects associated with utilization of all types sewage sludges is being questioned today even though it has been shown many times that composted sludges provide beneficial rather than negative environmental effects.
Some nurseries are now actively pursuing alternatives to composted sewage sludges. Composted livestock manures have the potential to replace composted sludges. However, a consistent, high quality product is required in this value-added market.  Research performed with funding from the Ohio Water Development Authority at the OARDC/OSU is now developing quality standards for composted dairy and swine manures for these markets.  Impacts of changes in parameters such as volatile solids, pH, total nitrogen, carbon to nitrogen ratio, and ammonia emissions during the composting process on plant growth are being evaluated for different manure and bulking agent combinations.  The objective is to provide quality control guidelines that will allow composters to accurately evaluate compost maturity and its application rate so that products can be produced that consistently meets the needs of the industry.  Results indicate that the quality of composts prepared from cow manure amended with straw as bedding is more predictable than that of manure mixed with sawdust.  Furthermore, either type of compost can suppress common root rots as well as induce systemic resistance to foliar diseases in plants. Thus, diseases in the foliage as well as those of plant roots can be minimized.


Lynn Willett (OSU) asked if sewage sludge is composted after undergoing anaerobic digestion.  Hoitink explained that typically it is not digested by anaerobic treatment first.  The most common practice is to treat the sludge aerobically to remove the most readily biodegradable materials and reduce the potential for odors. The next step is dewatering to produce a paste-like sludge. Finally, the solids are composted which destroys the pathogens and parasites. The final steps are curing and testing to be sure that the product meets all safety standards. Only after theses steps have been completed by certified labs can the product be released to the public. Thus it differs greatly from sewage sludge, the raw product.  Anaerobic digestion increases the cost of processing and creates a material that is less reactive and requires more bulking agents for composting to generate adequate heat for pathogen destruction.  Hoitink noted that composting of raw manure or sludge can generate more odors which must be controlled.

Tom Noyes (OSU Extension) asked if manure from a sawdust bedded system can be more efficiently composted if straw is added.  Hoitink responded that it should be ok as the straw should increase porosity and, because it decomposes more quickly than sawdust, increase the composting rate.  However, sawdust should not be added to straw unless a consistent system is adopted by farmers as it would reduce the predictability of the quality of the product. This poses problems for the most value-added markets only.  Hoitink noted that composting sand-laden manure is a challenge because the heat output is low causing water retention problems and requiring more bulking agents.

Lynn Willett (OSU) asked how much composted manure is needed to meet the needs of the nursery industry.  Hoitink noted that when composted bark began to be used in potting mixes, the market for it grew to 25 million metric tons in just a few years.  A similar increase in demand was seen as composted yard waste became available. More than 38 million tons are produced each year today. The same response is expected for composted manure because the nursery industry continues to grow. Furthermore vegetable growers are beginning to use composted manure. One large California carrot producer now treats more than 30,000 acres per year to improve the quality of the crop and reduce disease.

Willett noted concerns that composting increases ammonia in the atmosphere.  According to Dr. Henry Tyrell with the USDA, agriculture currently releases 3.5 billion kilograms of ammonia into the atmosphere.   A National Institute of Health study indicates that a 10% reduction in emissions would save $10 billion per year in health related costs*. Hoitink responded that the design and/or
operation of the composting system directly effects ammonia emissions.  An enclosed system and choice of materials for open systems as well as management procedures can reduce and even eliminate emissions.

Willett suggested that the ammonia issue needs to be addressed before a farm begins composting.  Hoitink noted that the reality is that market and regulatory forces will effect such change. The worst ammonia emission problems probably are caused on farms that apply liquid manures to fields covered with tall standing litter without incorporation of the material immediately after its application. Where ammonia emissions do pose a problem during composting such as at poultry (layer) operations, closed facilities increasingly are being installed that scrub exhaust air. Composting is not the solution to all manure problems but it is being adopted more commonly on farms today.

*Ammonia contributes to PM 2.5 – particulate matter 2.5 microns in diameter – in the atmosphere.  PM 2.5 is correlated with increased respiratory illness.

GORE cover composting:  Solid waste treatment in North America
Oley Sheremeta, Sheremeta Environmental Consulting

Of the 470,000 tons of organic waste produced in the U.S. each year, less than 3 percent is composted.  Odors and public perception are often cited as one of the primary reasons that composting sites are not approved or are closed.  The GORE Cover system can significantly reduces odors by the controlled use of a PTFE membrane that is permeable to oxygen but impermeable to large molecules.  In addition to the membrane, which covers the organic material during composting, the system includes a concrete floor and wall, blowers for aeration, and a winder for efficient movement of the cover.  The system also requires consistent management including preparation of materials to achieve a homogenous mixture with moisture content of 55-60 percent and monitoring of temperature and oxygen levels.  With this system, the composting process takes eight weeks.  The “heap” of organic material is covered by the membrane, which is secured to the ground, allowed to compost for four weeks, then moved and re-covered for two weeks for stabilization.  During the final two weeks of curing, the heap is uncovered.


Harry Hoitink (OSU) asked if freezing were a problem.  Sheremeta responded that the heat produced by the heap prevents freezing of the membrane except where it is in contact with the ground.  Placing 2-3 inches of porous material beneath the cover’s edge minimizes the freezing.

Bob Shanz (Garik Corp.) asked how moisture that condenses on the underside of the cover is returned to the pile.  Also, does it tend to run down the sides, leaving the center dry?  Sheremeta indicated that it is not a problem but that the specifics are confidential.

Jerry Richter (Garden Ridge Nursery) requested cost information for the system.  Sheremeta noted that costs are expected to be available by the end of March 2003.  Currently, the system is being used in seven reference facilities in the U.S. which GORE is using to collect cost data and to demonstrate its effectiveness.  The system is not turnkey and everything but the site preparation, which must meet specs, is provided by GORE.  The system has been used in Europe since 1994 and meets Germany’s stringent requirements.

Hoitink suggested that other than the cover, the basics of the system are standard.  Sheremeta replied that GORE’s insistence on providing the entire system is based on their desire to control all details so the success is ensured.

Hoitink noted that the cover should be needed only for the first four weeks as most odor compounds will be decomposed by then.  Sheremeta agreed but explained that the end market may have an impact.  If a finer product is required, the grinding that is done after the four weeks will expose fresh surface area and there will be a sharp, though brief, increase in the composting rate.

Bob Page (Farmore Farms) asked what GORE supplied for the price paid.  Sheremeta replied that most materials are provided including precast trenches (for aeration), steel trench covers, water traps, pipes, blowers, wiring and fiber optics with conduit blowers, mechanical winder and track for movement, GORE covers, oxygen and temperature sensors, PC with software and training.

Dave Ertl (OSU) asked for specifics of what is not supplied.  Sheremeta responded that the installation and cost of the civil work, including a cement or asphalt base and a cement wall with embedded steel to support the winder railing, are the responsibility of the buyer and must be installed according to GORE specifications.

Hoitink asked if GORE is partnering with a large dairy facility in the western U.S. as a reference site.  Sheremeta noted that there have been conversations but no commitment.  GORE is still looking for an agricultural site as they intend for references sites to illustrate the system for different climates and feedstocks.

Development of Composting Systems for Ohio Dairy and Hog Farms
Dr. Fred Michel, Ohio State University

A recent survey of manure handling practices used by Ohio dairies, indicates that about 50% have the potential to use composting to move nutrients off-farm economically and create a value-added product.  The feasibility of composting manure varies depending on the manure, bedding and amendments, which may be needed to reduce moisture in dairy or swine manure.  Research at the OARDC evaluated windrow composting of three mixtures:  dairy manure amended with sawdust, dairy manure amended with straw; and swine manure from a High Rise Hog facility which used wood shavings as bedding.  In addition, the effectiveness of composting sand-bedded dairy manure was evaluated.  These studies yielded the following results:

•    The wet weight of the compost, relative to the manure, decreased by 75%.
•    The volume of the compost decreased by 20-50%
•    Nitrogen loss was less than expected, ranging from 0-30%.
•    Moisture control was critical to obtain weight reduction.
•    Sand bedded manure can be composted if it is amended with organic materials.


Harry Hoitink (OSU) asked if the lower somatic cell count (SCC) for dairy cows bedded on sand is reflected in lower infection rates.  Michel noted that producers receive a premium for milk with levels below a specified SCC.  SCC’s can be reduced for organic bedding if it is well managed.   Jeff LeJeune (OSU) commented that clinical mastitis is not necessarily based on SCC.  (For a brief review of SCC and mastitis, see summary of Dr. Larry Smith’s seminar at http://www.oardc.ohio-state.edu/ocamm/smith.htm)

Ted Short (OSU) commented that it is generally assumed that composting results in a significant loss of nitrogen.  Why was that not the case in these studies?  Michel noted that the compost had higher than average C:N ratios as a result of the carbon-based amendments that were added to the manure to reduce the moisture content.

Lynn Willett (OSU) asked when the initial nitrogen measurement was made.  Michel responded that the initial measurement was made after the manure was mixed with the amendment.  Willett suggested that additional nitrogen would have been lost during transport of the manure from the barn to the compost pad.  Michel agreed but observed that such a loss would be true whether the manure was transported to a field for application or for any other manure management strategy.

John Smith (OSU) asked what C:N ratio is recommended to minimize nitrogen loss.  Michel suggested a ratio of 30:1.  Harry Hoitink (OSU) commented that differences in the decomposition of different amendments needs to be considered in addition to the carbon content.

Smith, referring to data that indicated straw amended dairy manure did not heat as effectively, asked if the chopping the straw would have an impact.  Michel noted that chopped straw had not been tried as an amendment but suggested that it should increase the composting rate.

A Columbus participant asked if the facility where sand (from a sand-bedded dairy) is added to composted yard trimmings had tested for pathogen reduction and, if so, at what point in the process.  Michel responded that pathogen testing in this system needs to be evaluated.  Currently, the materials are mixed with 1 part sand to 2 parts yard trimming compost, on a volume basis.

Srinand Sreevatsan (OSU) questioned the effect of composting on spore counts such as bacilli.  Michel noted that, to date, this has not been evaluated, but needs to be.  Hoitink added that the literature indicates that for some heat resistant microbes, anaerobic decomposition followed by aerobic composting can be effective for destroying heat resistant microbes.

Hoitink asked what composting system is most practical for a livestock operation.  Michel noted that an important consideration is minimizing the amount of material, especially amendments, but there are trade offs.  While straw has a higher volume initially than sawdust, chopping it first should help.  While sawdust has a lower volume and heats well in the early stages, it can require more time (200 days to 1 year) to reach stability.

Hoitink questioned the feasibility of static piles versus windrows.  Michel responded that in the study, the windrow size was probably too small.  Optimizing pile size is important in managing moisture efficiently.  Hoitink suggested that a static, aerated pile under a pole barn would require a smaller area than windrows and that the cover could help with moisture issues.  Michel noted that static piles might become anaerobic in the center if too large.  A fleece blanket (designed to permit transfer of air but not moisture) covering windrows may be a cheaper alternative to a pole barn.  Additional research is needed to evaluate optimal size.

Willett questioned whether temperature differentials within the compost pile result in some materials not reaching the temperatures (55 degrees C for 3 days) needed for pathogen control.  Michel noted that the temperatures reported were based on an average from six locations within the windrow taken over a period of 10 days.  During that time, the windrow was turned 2 to 3 times to mix the material.  This method should result in all material reaching the required temperature.  The exception could be the straw amended manure as high temperatures were not consistent during the first 10 days.

Michel also noted that during composting, the substrate changes resulting in a change in the microbial community present.  Research on composted yard trimmings (which usually only reach a maximum of 50-55 degrees C) demonstrated that the microbial population does change over time.  After 8 days, there was a significant change in the microbes of the genus containing E. coli and Salmonella.  However, since some pathogens can cause disease at very low levels, additional research is needed.

Compost Teas Production Practices
Dr. Steven Scheuerell, Oregon State University

Compost tea requires compost, water and time but additional options, including added nutrients, aeration, filtration, dilution, spreaders and stickers and tank mixes, may be used. The primary goal of brewing compost tea is to obtain nutrients and cultivate the beneficial microorganisms found in compost for application to nursery and farm crops. Anecdotal evidence and some industry data indicate that compost teas can have an impact on yield; however, as compost teas are relatively low in nutrients, mechanisms such as changes in soil biology or increased nutrient efficacy probably play a role. Laboratory and replicated field studies indicate that compost teas can induce disease suppression but the effectiveness varies with production method, amendment, application, environment and pathogen. Additional research is needed to better evaluate how the stability of the compost, brewing techniques, and application timing and methods affect the benefits of compost teas.


Brian McSpadden-Gardner (OSU) asked if the benefits for foliar diseases depend the number of microbes on the plant surface. He also questioned whether the potential for pathogens in the compost tea or metabolites being produced in situ are a concern for food safety. Scheuerell noted that for Botrytis and Pythium, research has indicated that the number of compost tea organisms colonizing a plant has been positively correlated to disease control.  For concerns about human pathogens, if they were present in compost tea then they could be applied to plants, however, survival of pathogens in this situation has not been investigated under agronomic conditions. Currently, there is no data indicating whether metabolites are created by the compost tea organisms on plant surfaces.

Harry Hoitink (OSU) asked if, for humid climates, the rain splashing on manure applied to fields acts as a "natural" tea. Such practices are not usually associated with contamination of crops. Scheuerell noted that the issue is complex and more data is needed that identifies the organisms present on the plant surface and the survival rate for varying conditions.

Fred Michel asked if non-aerated compost teas are anaerobic. Scheuerell indicated that the dissolved oxygen content in non-aerated systems depends on the stability of the compost, amount of water and the addition of fermentation nutrients. If the compost is relatively stable and the compost to water ratio is at least 1:10, the dissolved oxygen content is usually above 4 mg/kg (ppm).

Hoitink noted that the literature indicates that if compost is stable, coliform bacteria will not be a problem even with fermentation, but if soluble nutrients that support coliform growth are added, there may be a problem. Also, yard waste can support salmonella populations, so manure does not pose the only risk of contamination. Scheuerell noted that the literature does address regrowth of pathogens in composted biosolids in relation to compost stability. The relationship between stability of the compost used to make compost tea and the potential to support multiplication of human pathogenic bacteria in compost tea has not been evaluated. While commercial compost tea systems usually test clean, there is still a need for data to assess the risk across a range of compost tea production practices.

Sally Miller (OSU) asked for recommendations for compost teas, especially in nurseries with mini vegetables where damping-off is problem when watering is not done properly. Scheuerell responded that there are not specific recommendations and suggested discussing the pros and cons with the producer. Although there are no known contamination issues nor restrictions for conventional growers, they should be aware that there is a potential risk and that there could be liability issues. All available data indicate that if no nutrients are added to the tea, there is not a problem with increasing coliforms. For organic growers, the use of compost teas has yet to be clarified in the regulations, so the matter should be discussed with the certifier.

Miller asked whether damping off control is possible with no added nutrients. Scheuerell noted that it has not been demonstrated. He suggested that the best potential method to obtain sufficient quantities ofmicrobes, without adding nutrients that could support human pathogens, is to use high quality compost, a high ratio of compost to water, agitate extensively for about an hour, filter, and spray. Another compost tea production method that should be investigated for avoiding the growth of coliforms, yet obtaining high populations of beneficial organisms, is the use of cool water and relatively short culture times. A consultant in California has been successful in

producing compost tea using a process that includes 6-8 hours of active aeration, 50-60 degrees F water, and additions of molasses and kelp. In addition, in the west, many producers focus on applying compost tea to the rhizosphere using  surface or buried drip irrigation, so there is little risk of surface contamination.

Matt Kleinhenz (OSU) asked whether potato growers had been assertive in adopting the compost tea application practices used by one supplier of compost tea in Idaho that resulted in significant increased crop yields. Scheuerell noted that the data he had shown is not widely available but is available to him because of a close working relationship with the company. Other Idaho growers trying compost teas have had logistical problems with the fledgling compost tea industry that have resulted in some negative attitudes toward the use of compost teas. For this reason, once growers decide that compost tea can provide them measurable benefits, they usually chose to make their own compost tea to reduce costs and be in control of quality and timing.

Transforming Farm Residuals into Value-Added Products:
The Current State of Composting and Alternative Technologies

Robert Rynk

Concerns about water and air quality, odors and neighbors as well as the need for alternatives to fossil fuels and improved farm economics are creating opportunities for improved and new technologies for managing manure and other farm residuals.  Although compost basics have not changed in the past 30 years, management practices to optimize the process have been introduced as the market for compost continues to grow.  Ongoing challenges in composting include maintaining good neighbor relations, reducing odors and addressing air quality issues.  In addition, there is a need for research data on the environmental  impact and economic feasibility of composting.  However, compost has a positive image and new niches for its use are being developed, including remediation of lead contaminated soils and manufactured top soils.  In addition, there is a growing interest in additional feedstocks such as animal mortalities, food residuals and compostable paper.  In addition to composting, anaerobic digestion, gasification, and alcohol fuels are growing industries that offer opportunities to turn waste products into resources.


Brian McSpadden Gardner (OSU) asked if the environmental apathy Rynk noted as a challenge to the composting industry is a reflection of the downturn in the economy.  Rynk responded that his personal observations indicate the apathy appears to be a lack of interest and an increase in cynicism resulting in fewer concerns for the environment.  However, there is still strong student interest in environmental issues.

Maurice Watson (OSU) noted his involvement with the US Composting Council’s (USCC) Standards and Practices Committee in developing guidelines and specifications for compost use.  There are concerns that the guidelines could be used to restrict use and/or increase regulation of the industry.  Rynk noted that the specs must be tailored to a particular use increasing the complexity of the task.  For example, compost used along new highways require larger particle sizes which tend to be wood.  However, wood is not good for agronomic uses because it ties up nitrogen. 

Currently, the USCC has implemented the STA (Seal of Testing Assurance) which ensures testing procedures and ingredients.  The next step will be to develop some general guidelines for broad classes of use based on maturity.

Fred Michel (OSU) noted that a survey of Ohio dairies indicate that about 7% use composting as part of their manure management and asked if there are any changes in this practice.  Rynk responded that, based on personal observation, farms appear to be the only area that composting seems to be growing.  The growth is primarily the result of environmental pressures.

Ted Short (OSU) asked if there has been a change in the number of subscribers to BioCycle (a journal for composting and recycling) over the past several years.  Rynk said there’s been a slight decrease recently, but overall subscriptions have been relatively consistent over the past 8 years. 

Short asked whether other technologies, such as anaerobic digestion, are increasing in popularity due to increased press coverage.  Rynk noted that BioCycle is providing more information on bioenergy (approximately 1/3 of the coverage) because the composting industry is relatively stagnant.  While the change has not affected the number of readers, the bioenergy conferences hosted by BioCycle attracts a very different, though similar size, audience than those that focus on composting.  (For information on the upcoming conference, Renewable Energy from Organics Recycling, see http://www.jgpress.com/conferences1/conferences1.html

Peter Ling (OSU) asked if more data are needed to document odors during composting.  Rynk responded that there is a need for basic and field research to document the cause and distribution of odors.  However, accurately measuring odors is very difficult.

Ling asked if the lack of economic and other data reflects the stagnancy of the industry.  Rynk suggested that it in part reflects a lack of effort to collect the data, but the complexity due to high variability of biological systems also hampers research.

Watson noted that application of manure or compost to soil is affected by variations in soil temperature, moisture and type.  Rynk cited a study that indicated a significant reduction in irrigation needs after transitioning to organic agriculture and using compost.  More data is needed to verify the impact of compost amended soil on water needs including the economic value of decreased energy, water and labor costs.

Brian McSpadden-Gardner (OSU) suggested that the impact of compost on water needs is greater in the west because of a greater drought risk.  Rynk agreed and noted that there is a larger market for compost in the west.

A participant in Columbus suggested that vermicomposting should minimize odors as it proceeds at a faster rate and requires oxygen, reducing odors from anaerobic processes.  Rynk responded that he lacked direct experience with vermicomposting but had visited several sites, including a biosolids one, and had not observed odors.  However, vermicomposting must be done on a smaller scale as it requires organics be added in small, controlled amounts.

Rain Simulation to Evaluate Leaching from Compost Windrows
Harold Keener, Ohio State University

Studies to evaluate runoff volume and nutrient concentration from compost windrows were conducted at the OARDC in Wooster composting pad.  The 29,750 square foot pad has a slope of 1-2% with windrows parallel to the slope and a wood chip filter at the base and perpendicular to the slope to trap larger particles.  Runoff from the pad drains to a series of three wetland treatment cells designed to retain a 25-year rain event.  The 2003 study simulated rainfall for 100-, 25- and 5-year storms and measured total suspended solids, total dissolved solids, ammonia-N, nitrate-N, phosphorus, potassium and micronutrients.  The study concluded that the greater the rainfall, the larger the volume of runoff and the higher the concentration of nutrients.  A follow up study in 2004 assessed the effect of compost age on runoff volume and nutrient concentration.  The results indicated that the volume of runoff increased with the age of the compost, probably due to a crusting over of the surface of the windrow resulting in a hydrophobic effect.  While the concentration of most nutrients decreased with age of the compost, the total amount of nutrients lost showed no definite trends.  Additional research is needed to evaluate biological oxygen demand of the runoff and the effect of biofilters as well as to develop a model for predicting runoff parameters for different compost mixes.


Lynn Willett (OSU) asked if the wetland treatment cells are lined and, if not, is seepage through the soil a problem.  Keener noted that the cells are not lined but were designed to be impermeable.  There may be approximately 5% loss to the subsurface.

Willett asked if any adjustment for the wetland is needed to account for the time of year.  Keener noted that the there are two key issues involved.  It is assumed that the wetland does not function as well in the winter because there is not as much uptake from plants.  Also, management of water levels in the cells is critical as more water may need to be held in the winter whereas in the summer it may be pumped out and used to water windrows or irrigate crops.  The goal is to minimize discharge from the cells.

Diane Borger asked if there was replication of the 2003 data in the 2004 study.  Keener replied that the fourth windrow that was needed to do so was not available.   Both studies indicated the need for good housekeeping on the pads as material between the windrows can have a significant impact.  Runoff studies from covered windrows result in relatively high concentrations of nutrients, probably from the uncovered edges.

Willett questioned the dry matter percentage when the windrow is first formed and the percentage of dry matter in a mature compost.  Keener replied that the goal is 60-65% moisture when the windrow is formed with a reduction to about 45% moisture for a mature compost.

Borger asked if there was any odor from the runoff.  Keener noted that it was not noticeable, although those working with the samples may have noticed some.

Willett asked if the windrows were aerated using forced air or by turning only.  Keener responded that turning was the only method of aeration.  Data indicated that penetration of water is shallow at the top of the windrow but the base becomes more saturated as the compost matures.

Tom Zimmerman (ATI) asked why the base of the windrow has more moisture if the top is hydrophobic.  Keener noted that the data is still being analyzed and that more research is needed.  As more research is done, it will become clearer as to how a site should be designed and managed to minimize runoff.

Willett noted that most compost sites are not as clean as the OARDC site and asked how it is maintained.  Gerald Reid (OSU) responded that after turning the edges of the windrow are cleaned up.  However, some fine particles are left when a windrow is removed.

Composting and Anaerobic Digestion of Manure from Antibiotic Treated Calves
Osman Atilla Arikan, USDA-ARS, Animal Manure and By-Products Laboratory

The use of antibiotics for therapeutic purposes and growth promotion in livestock production results in the excretion of the antibioitic and/or its metabolites in manure and the potential for surface and groundwater contamination when the manure is applied to land.  Oxytetracycline (OTC), a broad-spectrum antibiotic, has been shown to reside in sediments for several months negatively impacting algae and crustaceans and increasing the potential to contribute to antimicrobial resistance to tetracyclines.  The objective of this study was to determine whether anaerobic digestion and composting would degrade OTC and its metabolites excreted in cattle manure and to assess the effects of OTC on anaerobic digestion and composting processes.  Manure from five beef cattle fed rations with OTC at standard concentrations was evaluated.  For the composting process, 99.8% of the OTC was removed compared to 27.4% for the anaerobic digestion.  In addition, the OTC residuals in the manure caused significant inhibition of biogas production during anaerobic digestion.

Referring to a graph depicting the rate of biogas production from OTC contaminated manure decreasing after five days in a digester, a Columbus participant suggested one might expect the opposite to  occur as microbes become more resistant to the antibiotic.  Arikan replied that during the first few days, the most biodegradable portion of the mixture is broken down thus masking the effect of the OTC and its metabolites.

Lynn Willett (OSU) asked if the composition of the biogas was analyzed.  Arikan noted that one sample was analyzed as having 50-60% methane.  Future studies will use gas chromatography to analyze the biogas, including fatty acids and hydrogen, to better understand the process.

Srinand Sreevatsan (OSU) asked how much antimicrobial activity is retained by the metabolites.  Arikan responded that he did not have the data for comparison with OTC.  Future studies will address the issue.

Harry Hoitink (OSU) noted that the strong adsorption of the OTC to the solid matrix in the composting studies may be affected by the maturity of the compost.

Research Review of Compost Used for Erosion, Sediment and Pollution Control
Britt Faucette, Filtrexx International

Control of runoff on construction and agricultural sites is critical to minimize erosion and prevent sediment and other pollutants from entering surface waters.  Although construction sites are considered point sources of pollution with erosion rates up to 25% greater than agricultural lands, research using compost products for runoff control on construction sites can be applied to farmland.  Current research indicates that specific compost applications can be more effective than standard runoff control practices but require the compost meet strict specifications for quality and installation.

Controlling erosion at construction sites requires designing a system that optimizes plant growth and water absorption. Erosion Control Blankets (ECB), a thick layer of compost blown onto disturbed soil, is effective in dissipating the energy from the impact of raindrops, increasing the water holding capacity and evaporation potential of the surface, slowing and dispersing the energy from sheet flow and optimizing vegetation growth.  Research comparing compost ECBs with hydromulch/silt fence treatments indicated that the ECB reduced the total runoff volume and peak runoff rate and increased infiltration volume both on Day 1 and 3 months later for a simulated storm with rainfall of 4 inches/hour.  In addition, the vegetative cover 3 months after installation was 3 times greater for the ECB and after 12 months had 1/3 fewer weeds. 

Controlling sediment and nutrient runoff requires interrupting the flow to allow trapping of sediments, absorption of nutrients and degradation of organic compounds.  Silt Soxx (SS), filled with a coarse compost, can be used to create a sediment and soluble pollution detention device or filter.  In addition to restricting water flow, which allows the sediments to settle, the SS is a more effective filter than a silt fence as it is less likely to become clogged, resulting in increased solids and nutrient removal over the long term and requiring less maintenance.

Rick Wilson (OEPA) asked if, during certification of the compost, clean water is run through the compost as a control to determine runoff nutrients before contaminated water is used.  Faucette replied that clean water is not used, but if there is a spike in nutrients, the compost will not be certified.  Electrical conductivity is measured to detect the presence of salts that would indicate nutrients.

Fred Michel (OSU) referred to a slide that indicated phosphorus (P) in the runoff.  Where is the P coming from?  Faucette noted that there are some nutrients in the compost and hydroseed as these are needed to establish vegetation.

Wilson mentioned that in western Ohio, an Ohio Department of Transportation group uses livestock manure from the fairgrounds along ditches to stabilize the soil and establish vegetation.  Faucette replied that it is not a standard practice.

Wilson asked if compost comes from large operations and how much, if any, is manure based.  Faucette noted that it is all yard/green waste compost and reiterated that the specifications are important.  Maturity is important.  Also, the compost needs to absorb water to reduce the total load.  Wilson commented that reducing soil movement will reduce P levels in surface water.

John Smith (OSU) asked about the process of applying the mulch blanket.  Britt clarified that the mulch itself is the blanket.  It is pneumatically blown onto the soil creating a mat.  For steep slopes, netting above or below the mulch increases stability.

Smith asked if the seed is mixed into the mulch.  Yes, it is injected into the system from a hopper.

Smith asked how to receive a copy of the Filtrexx Best Management Practices Design Manual.  It is available on the website (http://www.filtrexx.com/).

Dave Ritter asked how a filter berm or SS is inspected to determine whether or not it is functioning.  Faucette replied that the level of the water being held is the main indicator.  It is especially important for a berm which can overtop or blowout when water levels are too high.

Ritter questioned the life expectancy of the Silt Soxx.  Faucette replied that UV tests have been run on the different materials used. The actual life is a factor of material, sun exposure and rainfall.  Some are intended to be biodegradable and breakdown within 6 months.  Those made from HDPE last 2-3 years while those made from polypropylene are still intact. 

Penn State’s Organic Materials Processing and Education Center
Nadine Davitt, Penn State University

“Why can’t dining commons waste be composted?” A single question from a student group led to the Penn State University’s (PSU) Organic Materials Processing and Education Center (OPEC), a 10-year journey that continues today.  The first step was to identify the components needed to meet regulatory requirements and best management practices, then to develop partnerships within the University to ensure success.  The project had the potential to meet PSU’s goal for environmental leadership and waste reduction while creating an organic material that could be used on campus and supporting educational and outreach goals.  Capital and operational costs have been minimized by seeking equipment that could be utilized for other purposes, and funds have come from several sources, including grants, contributions by partners and administration, tipping fees and compost sales. 

Phase I of the project consisted of an 8-week pilot-scale test during which 8 tons of post-consumer food residuals and post-consumer napkins were collected from one dining commons using a 2-wheeled cart then composted.  Phase II increased the collection to three dining commons and added 4-wheeled carts for stability and a candy-cane lift truck to dump them, reducing labor requirements.  Phase III expanded collection of food residuals to include seven dining commons, the Student Union, a daycare center, two hotels, and organics from research units.  Fleece blankets were utilized, the compost was screened and on-campus utilization increased. Challenges during these phases included vector control, leaching, moisture control, a gravel pad, winter weather, contaminants, equipment limitations and storage.  As the Center continues with Phase IV, improvements include a larger concrete pad, storm water containment, accessible water and electricity, a vacuum to remove contaminants during screening, a bunker for storage, a storage building, and a scale.  As capabilities expand, challenges include availability of carbon, operating costs, equipment needs and competition form bio-energy initiatives.

Additional Resources:
The presentation may be viewed at http://www.ag.ohio-state.edu/~imagefolio/cgi-bin/ImageFolio31/imageFolio.cgi?direct=OCAMM (click on the TV icon dated 11-14-07). 

Sandra Tirado (OSU):  Is the leachate from the compost treated with a vegetative filter?
Davitt:  Runoff, not leachate, is treated by the vegetative filter, a 4-acre field, and the grass is cut 1-2 times per year.  Leachate is limited (generally nonexistent) and would not reach the vegetative filter before being diluted and becoming runoff.

Harold Keener (OSU):  How is the switch grass (carbon source) delivered?
Davitt:  It is in round bales, tied with string.  One bale is used per batch.
Gerald Reid (OSU): Is it ground in a mixer?
Davitt:  No, it is broken into 2-3 inch particles.

Keener:  How much extra time is required by dining hall workers to separate food waste during preparation?
Davitt:  No additional time is required; it just goes into a different container.  The collection of compostable materials is done daily and takes 1-1 ½ hours.  The collection requires a minimum of 1 ½ tons of material daily to cover expenses; about 25 tons are collected weekly.

Christina Redman (OSU):  How many tons are collected annually?  What is the disposal cost? 
Davitt:  Approximately 1,150 tons/year, most of which is food scraps.  The tipping fee for the compost site is $56/ton.  Landfill tipping fees are $66/ton. 

Angel Arroyo-Rodriguez (OEPA):  What are the design parameters for the bunker system?
Davitt:  The pre-cast walls are 8-ft tall.  The floor is tilted to the back and from the sides to the center to collect leachate.  Should the bunker need draining, the leachate is released through a 4-inch hole via PVC pipe, which is normally plugged.  The pipe can be plugged if needed.  The occasional discharge is only a few gallons and is discharged to a cow pasture.  Wood chips on the floor of the bunker help to absorb excess moisture.

Joe Goicochea:  Can you elaborate on the challenges of collecting post-consumer food scraps in the dining hall?  Would compostable tableware help?  Education?
Davitt:  They must accurately differentiate between what is recyclable, compostable and trash (e.g., salad dressing packets).  Consumer buy-in and willingness to make the correct decision is critical.  Currently, even with collecting only post-consumer napkins, silver ware in the container is a problem.  Each August employees are re-trained and videos are available.  Compliance is always a problem.
Goicochea:  At the Farm Science Review held in Ohio, the OEPA had a container for compostable cups but still received plastic bottles.

Mary Wicks (OSU):  How are post-consumer food scraps collected in the hotel facilities?
Davitt:  Employees bussing tables are trained to separate the materials; however, contaminants are still a problem (e.g., plates, cracker packaging).