Impacts of New Phosphorous Regulations on Composting of Animal Manures

The Problem

Concerns are mounting in states that have sensitive waterways about the release of P from manure and compost into ground and surface water. P is the limiting nutrient for many freshwater ecosystems and as such regulate the rate of eutrophication and oxygen depletion. The concerns have led to new regulations that limit the application of manure and in some cases compost products that have high concentrations of P.  Also, compost use in stormwater biofiltration swales has been called into question because of the potential leaching of P. There are concerns in the composting industry that the regulations will limit the application of compost and reduce the market for compost products.

Composting can theoretically increase the biological activity of the soil matrix and help the formation of aggregates that absorb nutrients. Compost also contains metals such as iron, magnesium, calcium and aluminum that help bind P to the soil particles.  Composting has a substantial impact on N as the high temperatures result in losses of ammonia. Depending on the stage of composting, the bacterial thermophilic phase of composting can release P during the breakdown of plant and animal tissue. In contrast the curing or fungal phase can bind nutrients into the hyphae and to the stabilized organic substrate. Additionally, soils high in organic C have lower bulk densities and prevent runoff because of the increased water holding capacity and infiltration rates*. The concept is that even though the overall P levels in the soils are increasing with compost application, only a small portion of the P is in the liquid phase and there is sufficient soil and plant uptake to limit P losses.  

*Spargo, J.T., G.K. Evanylo, and M.M. Alley. 2006. Repeated compost application effects on phosphorus runoff in the Virginia Piedmont. J. Environ. Qual. 35:2342–2351.

What did we do?

In 2014, Green Mountain Technologies (GMT) received an Animal Waste

Figure 1. Site map for Days End Farm
Figure 1. Site map for Days End Farm

Technology Fund (AWTF) grant from the Maryland Department of Agriculture to install an Earth Flow composting systems at Days End Farm (DEF, Fig. 1) in Howard County and Glamor View Farms in Frederick County.  There were two types of manures that were tested, dry pack manure from Glamour View Farms and bedded horse manure from Days End Farm.

Days End Farm Horse Rescue is a non-profit, volunteer-based animal welfare organization established in 1989 to provide care and treatment for horses that have been abused or mistreated.  DEF works to rehabilitate horses, find good homes for them and educate the public about humane treatment of horses. DEF cares for between 100-150 horses annually, rehabilitating them and preparing them for adoption.

Figure 2. Locator map for Glamor View Farms
Figure 2. Locator map for Glamor View Farms

Glamour View Farm (GVF, Fig. 2) is a 146-acre dairy operation which is a part of Lager Farms. Glamour View houses approximately 180 Holstein and Jersey cows.  In 2014, Green Mountain Technologies (GMT) and GVF received an AWTF grant from the Maryland Department of Agriculture to install an Earth Flow composting system at GVF in Frederick County, Maryland.

Description of the Earth Flow Composting System

The Earth Flow (Fig. 3 & 4) is an in-vessel composting system that integrates an automated mixing system, aeration system and moisture addition system into the vessel.  The Earth Flow system accelerates the composting process by providing optimum conditions for aerobic composting. The combination of these features facilitates a thermophilic composting process for horse manure and bedding in 10-14 days.

Figure 3. Earth Flow composter end view
Figure 3. Earth Flow composter end view
Figure 4. Earth Flow composter interior
Figure 4. Earth Flow composter interior

The Earth Flow has an integrated mixing system (Fig. 5) that allows the compost to be mixed on a daily basis (2-4 times per day).  The traveling auger is the key to the effectiveness of the Earth Flow. It provides seven different functions that facilitate the hot composting process:

  1. Shreds.  The auger breaks up manure balls to reduce particle size and expose nutrients to the microbes.
  2. Mixes.  The auger mixes material by smearing manure onto bedding.
  3. Aerates.  The auger continually fluffs the compost to add oxygen to the compost matrix.
  4. Distributes Moisture.  The auger sweeps up wet material from the lower portions of the compost pile and elevates it to the surface.  
  5. Homogenizes.  The auger homogenizes manure with bedding for an even distribution of nutrients.
Figure 5. Auger mixing system
Figure 5. Auger mixing system
  1. Transports.  The auger slowly increments compost from the load end to the discharge end.
  2. Stacks.  As compost reduces in volume, the auger continually stacks the material toward the back to maximize utilization of the space.

 

The Earth Flow is designed such that feedstocks are loaded on one end of the vessel and finished product is discharged from the opposite end of the vessel.

The Earth Flow at Days End Farm is operated as a continuous-flow system.  In a continuous-flow system, feedstocks can be loaded at any time on the load end and the traveling auger slowly migrates compost to the discharge end.  Material can be discharged once the vessel is full and/or the user is ready to discharge compost. The standard mixing pattern of the auger is shown below.

The basis of the study was to evaluate whether composting manure would reduce the amount of P, especially the water extractable P compared to raw manure.  The theoretical basis for this reduction is that composting would add more carbon and also tie up P in the increased biomass making it less available to run off.  While N can be lost to the atmosphere as ammonia or converted to elemental nitrogen gas, P is only transportable in liquid phase and can neither be created or destroyed by the normal biological processes.  P is essentially recycled through biomass and decaying plant and animal tissues release P that is the reabsorbed by new living tissue.

Samples of raw manure were collected prior to composting and the same manure was sampled 3-4 weeks later to determine the changes in nutrient levels and water extractable P.  Samples were taken every quarter for a one year period to assess any seasonal changes. One of the proposed applications for the compost product was bedding reuse so some of the focus of the study related to product quality as a recycled bedding material.

What we learned

Bedded Horse Manure

The average total Nitrogen (N) of 0.68% comprised 0.03% Ammonia-N of the loaded mixture (over the study period) with 52% moisture and 48% solids, with a total carbon content of about 40%, resulting in a C:N ratio of 29. Total P in the loaded mixture was 0.17% of which 0.40% was P2O5. For the compost produced during this period, the total N averaged 0.6% (5980 mg/kg) of which 0.06% was ammonia (577 mg/kg) and 0.54% was organic N (5436 mg/kg) and 470 mg/kg nitrate-nitrite N. The total carbon was 44.87% (44867 mg/kg), resulting in a C:N ratio of 214, with an average moisture content of 20% (Tables 3 and 4).

The average N:P ratio for the unloaded compost is 1.5 (5980:4140). Minerals analyzed from the manure and unloaded compost showed variability between samples collected on the different dates, but all measured concentrations of calcium, magnesium, sodium, iron, aluminum, manganese, copper, and zinc were within acceptable ranges. The nearly 30% decrease in moisture content over the composting period was measured, this is of interest as the compost process is optimal at 50% moisture content with a workable range from 40-60%. When moisture reaches 35% or less the material is suitable for screening when producing a product for landscape or horticultural uses. In addition, microbial decomposition (metabolic) activity decreases substantially resulting in insufficient metabolically generated heat within the compost mass. The TKN and C:N data indicate a substantial reduction in N during the compost process. We inquired with Waypoint about data reporting errors as the N values seemed surprisingly low. They had already disposed of the samples so they were not able to rerun the test. They did offer to retest and we may have them run the data points again. If the N data is correct, then a substantial amount of N would have been lost to the air as ammonia. In contrast, two of the three P values were higher in the compost than in the raw manure.  There may be several explanations for this trend. One point of interest as the bedding reuse continues is the accumulation of P in the compost product.

Dairy Dry Pack Manure

Penn State Labs performed the lab analysis of the raw manure and compost samples on 8/7/17. The lab samples were stored at Michael Calkin’s refrigerator and shipped to Penn State. Two samples were taken at the load and unload ends of the vessel each week and combined into a single grab sample.  Ammonia and Organic N were analyzed as well as P, extractable P and carbon. Because Glamor View is operated as a batch system, the initial sample on 5/28/17 represents the raw manure at both the load and unload ends of the vessel. Each subsequent lab analysis shows the weekly change in N or P as the manure turns into compost as shown below (Fig. 6 – 8).  

Figure 6. Nitrogen levels of dry pack manure before and after composting.
Figure 6. Nitrogen levels of dry pack manure before and after composting.
Figure 7. P2O5 levels of dry pack manure before and after composting.
Figure 7. P2O5 levels of dry pack manure before and after composting.
Figure 8. Water extractable phosphorus levels before and after composting.
Figure 8. Water extractable phosphorus levels before and after composting.

Winter 2017

The nutrient levels showed no clear trend of diminishment during the 3 weeks of monitoring as shown in Table 1. The average N actually increased which seems highly unlikely given ammonia losses typically experienced during composting. The good news is that it has reasonable fertilizer value when compared to typical composts. The average P2O5 levels were unchanged during the 3-week sampling also. The water extractable P showed a slight downward trend but once again the data was scattered. The only conclusion we can make from the data is that more P was liberated during the thermophilic phase of composting than was bound up by bacterial bodies.  In retrospect, additional water extractable samples should have been performed on the cured compost to see how much water extractable P is in the product immediately before the compost is applied to fields or gardens.

Table 1. Lab Analysis of Bedded Horse Manure Before and After Three Weeks of Composting
Average results for Compost Feedstock Loaded into the Earth Flow unit at

Days End Farm in

December 2015

Average results for Compost Unloaded from Earth Flow unit at

Days End Farm in

December 2015

TEST Dec 2015 Summary (%) Average result-Dec 2015 (mg/Kg) TESTα Dec 2015 Summary (%) Average result-Dec 2015 (mg/Kg)
As Received Dry basis
Nitrogen, N % 0.39 0.95
Ammonical-N % 0.07 0.16 Total Kjeldahl Nitrogen 1.12 11200.00
Phosphorus, P % 0.10 0.23 Total Phosphorus 0.33 3346.67
Potassium, K % 0.36 0.87 Total Potassium 1.10 11033.33
Sulfur, S % 0.06 0.14 Total Sulfur 0.19 1923.33*
Magnesium, Mg % 0.13 0.32 Total Magnesium 0.38 3760.00*
Calcium, Ca % 1.76 4.53 Total Calcium 2.35 23466.67*
Sodium, Na ppm 602.00 1480.00 Total Sodium 0.18 1773.33*
Iron, Fe ppm 889.00 2173.33 Total Iron 4310.00*
Aluminum, Al ppm 368.33 873.00 Total Aluminum 3500.00*
Manganese, Mn ppm 93.07 230.00 Total Manganese 278.67*
Copper, Cu ppm 8.05 19.77 Total Copper 26.33*
Zinc, Zn ppm 33.60 82.93 Total Zinc 91.33*
Boron, B ppm 2.50 6.12 Total Volatile Solids 78.14 781400.00
Test Result Result
Moisture % 59.5 Moisture † 31.46 Moisture †
Solid % 40.5 Total Solids † 68.54 685366.67
Additional Tests Result
P2O5 (as received) , % 16.41 C/N RATIO † 40.67
K2O (as received) , % 0.428 Carbon (TOC) † 45.43 454333.33
αAll values are on a dry weight basis, except as noted by†; Detection limit on all N series is on a wet basis.

*Within normal range, Analyses by Waypoint Laboratories, Richmond, VA

Figure 9. Nitrogen levels of dry pack manure before and after composting.
Figure 9. Nitrogen levels of dry pack manure before and after composting.
Figure 10. P2O5 levels of dry pack manure before and after composting.
Figure 10. P2O5 levels of dry pack manure before and after composting.
Figure 11. Water extractable phosphorus levels before and after composting.
Figure 11. Water extractable phosphorus levels before and after composting.

Spring 2017

Unlike the last sampling event over the winter, the nutrient levels showed a clear trend of diminishment during the 3 weeks of monitoring as shown in Fig. 9-11.  The average N reduced by 30% or more during the three weeks of composting. The average P2O5 levels showed a downward trend on the unload and unchanged on the load end which is expected given that P is not lost in the compost process.  The water extractable P had a clear downward trend for both the load and unload ends of the vessel with an average 42% reduction over the 3 weeks. Water extractable P is more important than a reduction in the P2O5 levels as it indicates the amount of P available for leaching.  In general, the lab data supported the trends that are typical of composting. It is not clear if the change over the winter results were seasonal or if the sampling methods were inconsistent. One possibility is the change in feed type that the heifers receive in the summer vs winter.  In retrospect, additional water extractable samples should have been performed on the cured compost to see how much water extractable P is in the product immediately before the compost is applied to fields or gardens. This sampling would have provided a more complete picture of the entire compost process for nutrient management.   

Next Steps

There is no doubt that P chemistry and bioavailability are complicated subjects.  Based on this work and studies done by Larry Sikora at USDA and John Spargo there needs to be a more comprehensive study performed with greater control of variables to demonstrate what might actually happen in the field with P availability and losses in compost. The other effort GMT is involved in is the development of a compost feedstock recipe calculator that includes values for different feedstock P concentrations and also performs C/P ratio calculations (Fig. 12).  The calculator has an interactive dial format that immediately shows the user how the volumes of different feedstocks changes not only C/N but C/P ratios as shown below. The hope is that the software will raise awareness about P and help to make compost products with balanced nutrient ratios.

Figure 12. User interface for Compost Calc recipe calculating software.
Figure 12. User interface for Compost Calc recipe calculating software.

Authors

Michael Bryan-Brown, Green Mountain Technologies, mbb@compostingtechnology.com

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.

Composting of Dairy Manure with the Addition of Zeolites to Reduce Ammonia Emissions

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Purpose

The purpose of this project was to demonstrate the effects of adding natural clinoptilolite zeolites to a dairy manure compost mix at the moment of initiating the composting process on ammonia emissions, nitrogen retention, composting performance, and characteristics of the final compost product. A typical dairy cow in the U.S. produces approximately 148 lb of manure daily (feces and urine, not counting bedding; Lorimor et al., 2000). This amounts to millions of tons of monthly manure production. On-farm composting of manure is one of the most-used practices to manage dairy manure in Idaho. Composting reduces manure volume between 35 and 50%, which allows the material to be significantly more affordable to transport than fresh, wet manure. Composting converts the nitrogen (N) present in the raw manure into a more stable form, which is released slowly over a period of years and thereby not totally lost to the environment. Composting contributes to alleviating problems associated with ground and surface water contamination and also reduces odor complaints (Rink et al., 1992; Fabian et al., 1993). During the manure handling and composting process, between 50 and 70% of the nitrogen can be lost as ammonia if additional techniques are not used to increase nitrogen retention. In most cases, manures from dairies and other livestock operations don’t have the proper carbon to nitrogen (C:N) ratio to be composted efficiently without added carbon (usual straw bedding has a C:N of 60 to 90). Dairy cow manure is rich in nitrogen (C:N ratios below 18:1), causing a great proportion of the available nitrogen to be lost as ammonia due to the lack of carbon to balance the composting process. The loss of nitrogen from manures as ammonia reduces the nutrient value of the manure, produces an inefficient composting process, and generates local and regional pollution. Lack of carbon also results in a lower-grade compost that can carry elevated concentrations of salts, potassium and phosphorous. In many arid zones there are not enough sources of carbon to balance the nitrogen present in the manure.

Zeolite is a mineral defined as a crystalline, hydrated aluminosilicate of alkali and alkaline earth cations having an infinite, open, three-dimensional structure. Zeolites are able to further lose or gain water reversibly and to exchange cations with and without crystal structure (Mumpton, 1999). Zeolites are mined in several western U.S. states where dairy production also is concentrated. This paper showcases a project that explored the effects of adding natural zeolites to dairy manure at the time of composting as a tool to reduce ammonia emissions and retain nitrogen in the final composted product.

What did we do?

This on-farm research and demonstration study was conducted at an open-lot dairy in southern Idaho with 100 milking Jersey cows. Manure stockpiled during the winter and piled after the corral’s cleaning was mixed with freshly collected manure from daily operations and straw from bedding and old straw bales, in similar proportions for each windrow. The compost mixture was calculated using a compost spreadsheet calculator (WSU-Puyallup Compost Mixture Calculator, version 1.1.; Puyallup, WA). Moisture was adjusted by adding well water to reach approximately 50% to 60% moisture on the initial mix. Windrows were mixed and mechanically turned using a tractor bucket. Three replications were made on control and treatment. The control consisted of the manure and straw mix as described. The treatment consisted of the same mix as the control, plus the addition of 8% of clinoptilolite zeolite by weight during the initial mix. Windrows were actively composted for four months or more. Ammonia emissions were measured using passive samplers (Ogawa & Co., Kobe, Japan) for the first five to seven days after building each windrow (called turn 1 in Figure 1) and after the two subsequent turns. Ammonia emissions per measurement period and per turn were obtained. Three periods of one to three days at the time of building each windrow and after the first turn were measured. After the second turn, two measurement periods of three to four days were made. Values of mg NH3-N/m3 are time-corrected by minutes of sampling (Figure 1). Complete initial manure (compost feedstock mix) and final screened compost nutrient lab analyses were performed for each windrow. Analyses of variance (ANOVA) on lab data and on ammonia samples were performed using SAS 9.4 (SAS Institute, Cary, NC).

Figure 1. Ammonia emissions per period and turn

What have we learned?

The addition of 8% w/w natural zeolites to the dairy manure compost mix on a mechanically turned system using a tractor bucket reduced cumulative ammonia emissions by 11% during the first three turns (Figure 2) and showed a significant reduction trend in ammonia emissions. Figure 1 shows the differences and trend line in ammonia emissions per monitoring period and per turn. Treated windrows’ cumulative emissions were significantly lower (P<0.05) at 2.76 mg NH3-N/m3 from control windrows at 3.09 mg NH3-N/m3. Nitrates (NO3) on the composted treatment (702 ppm) were 3 times greater (p=0.05) than the control (223 ppm) (Figure 3). These results demonstrate that the addition of natural zeolites has a positive effect on reducing ammonia emissions during the composting process and increasing the conversion to nitrates, retaining nitrogen in the compost in a form that is more available to crops.

Figure 2. Cumulative ammonia emissions

Figure 3. Nitrate, ppm before and after composting

Future Plans

Field days and journal publications about this project are expected to occur within the next year.

Corresponding author, title, and affiliation

M. E. de Haro-Martí. Extension Educator. University of Idaho Extension, Gooding County, Gooding, Idaho.

Corresponding author email

mdeharo@uidaho.edu

Other authors

M. Chahine. Extension Dairy Specialist. University of Idaho Extension, Twin Falls R&E Center, Twin Falls, Idaho. H. Neibling. Extension Irrigation Engineer. University of Idaho Extension, Kimberly R&E Center, Kimberly, Idaho. L. Chen. Extension Waste Management Specialist,

Additional information

References:

Fabian, E. F., T. L. Richard, D. Kay, D. Allee, and J. Regenstein. 1993. Agricultural composting: a feasibility study for New York farms. Available at: http://compost.css.cornell.edu/feas.study.html . Accessed 04/28/2011.

Lorimor, J., W. Powers, A. Sutton. 2000. Manure Characteristics. Manure Management System Series. Midwest Plan Service. MPWS-18 Section 1. Iowa State University.

Mumpton, F.A. 1999. La roca magica: Uses of Natural Zeolites in Agriculture and Industry. Proceedings of the National Academy of Sciences of the United States of America, Vol. 96, No. 7 (Mar. 30, 1999), pp. 3463-3470

Rink, R., M. van de Kamp, G.B. Willson, M.E. Singley, T.L. Richard, J.J. Kolega, F.R. Gouin, L.L. Laliberty Jr., D.K. Dennis. W.M. Harry, A.J. Hoitink, W.F.Brinton. 1992. On-Farm Composting Handbook. NRAES-54. Natural Resource, Agriculture, and Engineering Service. Cooperative Extension. Ithaca, New York.

Acknowledgements

This project was made possible through a USDA- ID NRCS Conservation Innovation Grants (CIG) # 68-0211-11-047. The authors also want to thank the involved dairy farmer and colleagues that helped during this Extension and research project. Thanks to Dr. April Leytem and her technicians at USDA-ARS in Kimberly, ID, for the loan of the Ogawa passive samplers and for sample analysis.

PA Finishing Swine Barn Experience: Changing from Mortality Burial to a Michigan Style Composting Barn

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Purpose

In the spring of 2014, the farmer with a 2020 finishing pig barn, wanted to change from burial of mortality to composting the mortality. We will document the change and the use of the composting barn from July 2014 to Dec 2016.

What did we do?

This 2020 finish pig barn space has about 3% mortality and expects about 250 deaths per year to compost. We discussed building a PA Michigan single wall compost barn design. The farmer built a 24×40 compost barn, with a 3 feet center dividing wall. The barn was completed in the summer of 2014 and we will track the pig barn turns and compost barn mortality loadings from July 2014 to December 2016. The barn has used about 56 cubic yards of woodchips/ bark mulch the first year and then replaced with about 40 cubic yards of sawdust for the second year.

The compost temperatures have reached 130 Degrees F and the farmer is very pleased with how the barn works and how he can mix and turn the compost. The presentation will cover barn costs, barn design and sawdust mortality loading and turning.

Field with windmills and barn
PA Michigan compost barn built at the end of the hog barn

Compost heap under shelter
Excellent example of free flowing air into the compost piles while
having a center push up wall to help turn the piles

What have we learned?

We have documented the farmers use of the barn, the mortality rates, compost sawdust and woodchip use, and mixing schedules. We have also documented the mortality cost rates for this farm.

Future Plans

We will highlight this PA Michigan compost barn type to other pig barns and document the use of them in Pennsylvania.

Corresponding author, title, and affiliation

J Craig Williams

Corresponding author email

Jcw17@psu.edu

Additional information

http://extension.psu.edu/animals/health/composting

http://msue.anr.msu.edu/program/info/managing_animal_mortalities

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Elimination of Equine Streptococci from Soiled Equine Bedding


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Purpose            

Streptococcus equi subspecies equi (S. equi), causes the potentially fatal respiratory disease in horses known as “strangles”, while the closely related Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) causes potentially fatal infections in humans. A study was undertaken to determine the survival of these 2 organisms in compost and soiled bedding.

What did we do? 

Dacron bags were filled with a feedstock mixture of soiled equine bedding and feed waste at ratios of 3:1 (C:N ratio 40.6), 1:1 (C:N ratio 31.9), and 1:4 (C:N ratio 25.4). The Dacron bags were inoculated with S. zooepidemicus, and placed in 3 compost windrows of the same 3 feedstock ratios 24 h later. Streptococci were quantified at different time points. Next, S. equi was inoculated into Dacron bags then placed into a compost windrow of the same feedstock ratio. Streptococci were quantified. To rule out killing of both Streptococcal species by microflora during the 24 h storage period, samples of soiled equine bedding, both autoclaved and non-autoclaved, were inoculated with S. zooepidemicus and periodically sampled. A repeated study was conducted with S. equi. To determine the role of moisture on the killing of S. equi in equine waste, soiled equine bedding was dried at 37 °C for 48 h and sterile water then added to dried bedding.

What have we learned?             

Microbes in soiled equine bedding may eliminate Streptococci, indicating that normal compost microflora may provide sustainable methods for the control of human and animal pathogens.

Future Plans    

Future studies could assess the role of individual bacterial species in the abatement of Streptococci, and possible additives to a compost pile which might increase numbers of streptocidal organisms. In addition, compost could be examined to discover novel antibiotics or bacteriophages which may be used for disease control.

Corresponding author, title, and affiliation        

Alexandria Garcia, Graduate Student, University of Maine

Corresponding author email    

Alexandria.poulin@gmail.com

Other authors   

Dr. Robert Causey, Associate Professor at University of Maine, Scott Mitchell, Student, Kathleen Harvey, Student, Ashley Myer, Student, Mark Hutchison, Extension Professor, and Martin Stokes, Professor

Additional information               

Garcia, Alexandria, “Abatement of Streptococcus equi in Equine Compost” (2016). Electronic Theses and Dissertations. 2435.

http://digitalcommons.library.umaine.edu/etd/2435

Acknowledgements       

Maine Agricultural Center, Dr. M. Susan Erich, Mark Hutchinson

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Composted Horse Manure and Stall Bedding Pilot Project

Why Study Compost as Bedding for Horses?

The purpose of this project was to study and promote the use of compost as an alternative horse stall bedding and encourage horse owners and managers to think more creatively about manure management. Our objective was to reduce bedding use, and improve manure management practices at equine facilities in Snohomish County, Washington State.

Recreational and professional horse owners contribute to maintaining agricultural open space and supporting the agricultural infrastructure and local economy. Horse owners have historically been overlooked as contributors to animal agriculture, and as a result many horse owners lack a basic knowledge about manure and nutrient management. They are not aware of their impact on water and soil quality. Disposal of used stall bedding is costly for horse owners in northwestern Washington State, and has a potentially large impact on water quality. Disposal practices often include filling in low spots and ravines, or building massive piles. Composting manure at high temperatures eliminates pathogens and parasites, stabilizes nutrients, and reduces odors and vector attraction.

What did we do?

The Snohomish Conservation District (SCD) worked with ten commercial and two private equine facilities to test the use of compost as an alternative horse stall bedding material. Facilities ranged in size from 5 to >20 stalls. The primary system used for composting and reusing bedding involved a micro-bin composter (O2 Compost, Snohomish, WA) and a Stall Sh*fter® (Brockwood Farm, Nashville, IN). Micro-bins were assembled on-site and filled with used stall bedding (Fig.1-2).

Figure 1. Assemble compost micro-bin on site and fill with manure and beddingFigure 2. Turn on blower to provide aeration and monitor temperature

After 30 days of composting, the bin was emptied and the manure was separated from the bedding (Fig. 3). The composted bedding was then used in a stall (Fig. 4). Equine facility managers provided feedback on the effectiveness, perception, and impacts of using the compost as stall bedding. Results varied between trial sites based on type and quantity of bedding used, season, and stall management practices.

Figure 3. After 30 days of composting, empty the bin and sort the composted manure from the bedding using the Stall Sh*fter (registered trademark)

Figure 4. Use composted bedding in the stall and composted manure in the garden.

What have we learned?

Composted stall waste makes a soft absorbent bedding for horses or other livestock. Composted bedding is less dusty than shavings or wood pellets, darker in color, and has a pleasant earthy odor. There were no reports of composted bedding increasing stall odors or flies, or negatively impacting horse health. The best results were reported when mixing the composted bedding with un-composted bedding in equal proportions or two parts compost to one part bedding. There were some reports of horses with skin and respiratory conditions improving during the time they were on composted bedding, including thrush in the feet, hives and “rain rot” on the body, and “scratches” on the legs.

When separating the composted manure from the bedding, the amount and type of bedding determines the effectiveness of a bedding re-use system. Concern about appearances was more prevalent than concern about disease or parasite transfer. Even though barn managers were not entirely ready to make the switch to composted bedding, this project helped start many conversations (in person, through publications, and social media) about manure management and resource conservation. It was a great opportunity to help horse owners make the mental leap from “waste” to “resource”.

Future Plans

This project demonstrated that compost is a safe and effective horse stall bedding. Future work should be focused in three areas:

1. Developing systems for making composted bedding that are practical on a large scale and provide an economic incentive for large equine facilities to recycle their waste.

2. Outreach and education programs directed at horse owners who board their animals at commercial facilities. Would some horse owners be willing to pay a premium to board their horses at a facility that is managed in an environmentally sustainable manner?

3. Clinical trials to examine the effects of composted bedding on skin and respiratory conditions.

Author

Caitlin Price Youngquist, Agriculture Extension Educator, University of Wyoming Extension cyoungqu@uwyo.edu

Additional information

Visit http://BetterGround.org, a project of the Snohomish Conservation District.

The full report, including photographs of trial sites, is available on the Western SARE website: https://projects.sare.org/sare_project/ow11-315/

Acknowledgements

I would like to thank all of the farm owners and managers who very graciously participated in this project and were willing to try something new. The contribution of time and energy is very much appreciated.

Thanks also to the staff at O2 Compost for their efforts, ideas, and creativity. This would not have been possible without them.

And Mollie Bogardus for helping take this project to the next level, and explore all the possibilities.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

Relative Mineralization Rates of Manure and Effect on Corn Grain Yield and N Uptake


Why Is It Important to Study Availability of Manure Nitrogen?

Application of fresh and composted manure as a fertilizer source in corn production has long been a useful practice in many sustainable crop production systems especially when phosphorus, and not nitrogen (N), is the primary nutrient of interest. But when manure is applied as the primary source of N, despite several agronomic advantages associated with manure use, there is a high risk of ground water pollution, and often times, would produce lower yields and grain protein than inorganic fertilizers. Nitrogen mineralization and availability from manure is difficult to predict. Therefore estimating the amount of crop N uptake that may be attributed to manure applied in the same year or to its residual impact, can be a useful approach towards quantifying a supplementary quantity of inorganic N fertilizer with the manure.

What did we do?

yield response to manureThis study measured in situ relative soil N mineralization rates (flux) during three growing seasons of continuous no-till (2013 and 2014) corn in Carrington, ND. We applied fresh (FM) and composted beef feedlot manure (CM) only once in spring 2012 at N rates of 90, 180, and 240lbs/A as FM, and 90 and 180lbs as CM. These rates were applied based on the calculation that 50% of N from FM and 25% of N from CM, would be available the first year. Other treatments were urea at 90, 150, 180, and 240lbs N/A, plus a check at 0lbs/A. In 2013 and 2014 urea was applied to respective plots, based on soil test, to raise the N levels to the respective 2012 N levels. We used the randomized complete block design with four replicates. Three replicates were used to measure soil N (NO3- + NH4+) mineralization rates bi-monthly with Plant Root Simulator probes (PRS™), from the urea fertilized and manured plots at the 0, 90 and 180lb levels at 4-6 leaf growth stage. Four pairs of PRS™ probes were buried in the top 6 inches near corn roots and replaced every two weeks for four sampling dates. We measured yields, protein content, and N uptake.

What have we learned?

N mineralized near corn roots, 2014Yields were generally low in all three years of this study, well below the average for this region. Bi-monthly N mineralization was significantly higher as N increases with urea as N source during the early sampling dates (Figures 2 and 3) and subsequently declined to similar levels as the manure treatments. It is therefore possible that the plants benefited from higher early uptake of N from urea up to the early stages of peak corn N uptake but not enough to produce significantly higher yields than the manure treatments. Analysis of variance showed no significant treatment effects for yields in 2012 (α = 0.05) but grain protein differences were significant. These differences were observed only between the check and 180 lbs N in 2012. The highest mean grain yield was recorded with the 90 lbs N treatment where, the residual soil N at planting was just 33 lbs. The protein level was also significantly higher than the check and CM plot that received 180 lbs N in 2012, and with a soil residual N prior to 2013 planting, at 35 lbs. Each year, grain yields responded positively to N rates (applied as urea) and residual N levels from FM but not with CM. Since corn was grown for three continuous years, unsurprisingly yields declined with years of production since N was not applied to the FM and CM treatments after first application in year one. Similarly, yield decline was observed with urea over the three years but not as steep as the FM and CM treatments. The FM at 240 lbs N, and urea at 180 and 240 lbs treatments produced significantly higher grain protein than the check in 2012 (data not shown). Lower N mineralization and very likely, lower N availability was observed with the CM treatments especially at 180 lbs N, which consistently scored the lowest mean yield and protein in 2013 and 2014. Grain yields were consistently higher at 90 lbs N than 180 lbs N with the CM treatment. N mineralized near corn roots, 2014Summer droughts of 2012 and 2013 at this site and possibly, factors associated with continuous corn production (e.g. disease, temporal N immobilization) compounded the effects of urea treatments even though N uptake was consistently higher with urea. Total N taken up in corn grains from the FM and CM treatments increased with N rates but decreased with time (Table 1). From this study, corn grains took up more N from the plots treated with FM than the CM over the three-year period of the study. Subsequent changes in soil conditions such as moisture, N leaching, temperature, can sometimes limit the efficiency of inorganic fertilizer uses, and favoring low cost alternative uses such as manure especially if the prevailing conditions enhance N mineralization from manure or soil organic matter. Based on N input plus soil N status at the beginning of planting every year, corn N uptake efficiency was in the order: Check>FM>CM>Urea, with efficiency decreasing at higher N rates. The minimum proportion of grain N uptake by any treatment to the single highest N uptake for any urea-N treatment (considered as a reference) in a given year, was 42% for the check in 2013.

soil nitrogen at planting and mean yearly uptake in corn grain

Future Plans

Relative contribution of nitrogen from the fresh and composted manure treatments and residual N will be used to estimate the percentage of N coming from these treatments over a three-year period. This will be used to establish new studies to assess different levels of fertilizer N to apply with manure to improve on the grain protein content and yields.

Authors

Jasper M Teboh, Soil Scientist, Carrington Research Extension Center, North Dakota State University Jasper.Teboh@ndsu.edu

Szilvia Zilahi-Sebess, and Ezra Aberle

Additional information

More detailed results from 2013 can be found in the North Dakota Corn Growers 2013 Annual Report at: www.ndcorn.org/uploads/useruploads/annual_report.pdf

Acknowledgements

North Dakota Corn Growers Association, Western Ag Innovations, Mr. Ron Wiederholt, Mr. Blaine G Schatz (Director, CREC)

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

Composting Swine Slurry to Reduce Indicators and Antibiotic Resistance Genes


Purpose 

Over the last twenty years there have been considerable increases in the incidence of human infections with bacteria that are resistant to commonly used antibiotics. This has precipitated concerns about the use of antibiotics in livestock production. Composting of swine manure has several advantages, liquid slurries are converted to solid, the total volume of material is reduced and the stabilized product is more easily transported off-site. The goal of this study was to determine if composting can also be used to reduce the concentration of indicators and bacteria containing genes for antibiotic resistance (AR) in swine manure.

What did we do? 

Sample Analysis:

Compost trials were conducted in either fall (FT) or spring (ST) and piles were turned once, three times or upon reaching 65 ºC. Microbial indicators and populations with AR genes for tetracycline, erythromycin and sulfonamide resistance were quantified by culture and/or quantitative, real-time (qPCR) analysis.

Compost materials and conditions:

Decomposed materials (a mixture of swine slurry and woodchips) were obtained on two separate occasions from swine high-rise finishing facilities (HRFF) located in western Kentucky. The HRFF houses between 4,000 and 4,800 swine which are placed in the facility at 18 to 20 kg and are removed after three months (weighing about 105 kg). The high-rise floor raises the living area 3.7 m above the ground. Manure, excess feed, water and wastewater drop through slatted floors into 2.5 cm screened woodchips (average size 1.9 ± 0.9 cm). The slurry-woodchip material was turned up to three times per week while under the HRFF. When the material was visibly moist, reducing its ability to absorb additional waste materials, it was removed from the facility for finishing in windrows. In fall 2011 (FT) and Spring 2012 (ST), HRFF slurry-woodchip mix (approximately 60 m3 weighing 48.4 Mg) was brought by semi-trailer trucks to the Western Kentucky University Agricultural complex where ma terials were divided into three or four windrow piles. In the FT, swine slurry-woodchip mixes having a bulk density of 849.6 kg m-3 and consisting of around 19.6 m3 of material were formed into three piles of approximately 10.4 m x 2.1 m x 0.9 m (L x W x H). In the ST, swine slurry-woodchip mixes having a bulk density of 778.4 kg m-3 and consisting of around 18.8 m3 of material were formed into three piles of approximately 5.8 m x 2.7 m x 1.2 m (L x W x H) and a fourth batch (unturned) was left piled at the side (0X; 3.6 m3). In each study, piles were turned using a windrow compost turner either once per week (1X), three times per week (3X) or upon the internal compost temperature reaching 65 ºC (@65). Compost for the FT @65 treatment heated to 65 ºC by day 14 and was turned 11 times over the course of the trial. However, during the ST, the @65 pile did not heat for the first 63 days (mean temperature 27 ± 8 ºC) therefore weekly turning was initiated at that time. Samples were taken on days 0 and three and then weekly for the first 12 weeks and bi-weekly until composting was stopped at day 112 for the FT and day 142 for the ST.

What have we learned? 

In the FT, concentrations of enterococci decreased below culturable detection within 21 days, corresponding with a 99% decrease in detection by qPCR (Fig. 1). Similar decreases in qPCR detection in the ST took longer (day 49 or day 77 of composting). Changes in the concentration of bacteria with AR genes varied by antibiotic type (erythromycin (36% – 97%), tetracycline (94% to 99%) and sulfonamide (53% to 84%) and compost season (greater decreases in ST). There were few differences based on turning regime. Even the unturned compost pile had 90%, 98% and 56% reduction in bacteria resistant to erythromycin, tetracycline and sulfonamide, respectively.

Results suggest that composting effectively decreases the concentration of indicators and AR genes in swine manure. As concerns over antibiotic resistance and pathogens increase, composting provides a valuable manure management tool for decreasing contaminants and improving the value of this material as a soil conditioner.

Future Plans    

Volume reduction, low moisture and low readily degradable organic matter suggest that the finished compost would have lower transportation costs and should provide value as a soil conditioner. Studies are warranted to evaluate its agronomic value as an alternative source of plant nutrients. Future studies will be conducted to evaluate the nutrient value this compost as an organic fertilizer for row crop production.

Authors       

Kimberly Cook, Research Microbiologist, USDA ARS kim.cook@ars.usda.gov

Carl Bolster, USDA ARS; Karamat Sistani, USDA ARS

Additional information                

http://www.ars.usda.gov/main/site_main.htm?modecode=50-40-05-00

Acknowledgements      

This research was conducted as part of USDA-ARS National Program 214: Agricultural and Industrial By-products: CRIS 6445-12630-004-00D. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA.

Proceedings cook figures 1

Proceedings cook figures 1
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Proceedings cook figures 2

 

 

 

 

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

Antibiotic Losses during Thermophilic Composting

Purpose

Residual antibiotics in land-applied manure and biosolids present a potential threat to public and ecological health, so it is important to determine antibiotic removal efficiencies for manure and biosolids waste management practices and to identify conditions that enhance antibiotic degradation.

What we did

Loss of the antibiotics florfenicol, sulfadimethoxine, sulfamethazine, and tylosin was studied during pilot-scale static pile thermophilic composting and the effects of temperature and feedstock particles on antibiotic removal rates were tested. The antibiotics were spiked into dairy manure solids and wastewater biosolids, and treatments included aerated and non-aerated manure and biosolids/wood-product (1:3 v/v) composting.

Figure 1. Applying antibiotic solution to biosolids

Figure 1. Applying antibiotic solution to biosolids

What have we learned

Results showed no significant differences between aerated and non-aerated treatments; on average ≥85%, ≥93%, and ≥95% antibiotic reduction was observed after 7, 14, and 21 d of composting. Greater antibiotic reduction was observed in manure compost compared to biosolids compost for florfenicol (7, 14, 21, 28 d) and tylosin (7, 14, 28 d); however, there was no significant difference for sulfadimethoxine and sulfamethazine. Peak temperatures were 66-73°C, and ≥55°C was maintained for 6-7 d in the biosolids compost and 17-20 d in the manure compost.

Bench-scale experiments conducted at 25, 55, and 60°C showed that lower temperature decreased removal of the sulfonamides and tylosin in both feedstocks and florfenicol in the biosolids. The presence of compost particles increased antibiotic loss, with time to 50% dissipation ≤ 2 d in the presence of solids (60°C), compared to no degradation in their absence. These results indicate that thermophilic composting effectively reduces residual antibiotics in manure and biosolids.

Figure 2. Mixing biosolids and wood shavings

Figure 2. Mixing biosolids and wood shavings

Figure 3. Mixing biosolids and wood shavings

Figure 3. Mixing biosolids and wood shavings.

 

Authors

A. Bary*, S.M. Mitchell*, J.L. Ullman**, C.G. Cogger*, A.L. Teel*, R.J. Watts*

Washington State University*, University of Florida**.

Andy Bary, bary@wsu.edu

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

Figure 4. Compost bins

Figure 4. Compost bins

Benefits of Bedding Reuse for the Equine Industry

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Why Studying Bedding Reuse for Horses?

To examine the financial, operational and health benefits of re-using composted bedding in the equine industry.

What Did We Do?

Stable waste, consisting of manure, urine and wood shavings, is a readily compostable feedstock that generates heat and can be transformed into finished homogenous compost, which can be used as bedding for horses and other livestock.  This transformation can be completed in as little as 2 weeks with in-vessel technologies, 15-25 days in aerated site-built systems and 20-30 days in aerated static pile (ASP) systems.  If composting is done in a biologically active, aerobic environment such as the systems mentioned above, the process destroys weed seed, parasites and harmful pathogens. These benefits are the result of system controls such as a correct ratio of C:N, moisture, porosity of the pile, and temperature.  The in-vessel composting system offers the most comprehensive control of these factors ensuring the most favorable results. 

The biological process that occurs when the stable waste is blended utilizes the leachable N and binds it in the organic matrix keeping it secured.  There is also a reduction in N during the process as it becomes volatile and escapes through vaporization.  The phosphorus is utilized by the bacteria during the process, reducing the amount available to leach by at least 50%.   Since both N and Ph are needed for cellular growth, they get locked in the cells of the growing bacteria.  This process generates heat, removing the moisture, killing pathogens and creating drier and more absorbent material for bedding re-use.

IOS Ranch, a private 20 horse show stable on Bainbridge Island, Washington, was the study site for this paper.  They purchased an Earth Flow in vessel system and it is from this system that the lab results and observational data were collected.  Their bedding of choice is medium sized bulk shavings.  Also studied over the same period of time was the Earth Flow in-vessel system at Joint Base Myers/Henderson in Arlington, Virginia.  The US Army Caisson horses stabled there are bedded on pelletized bedding.  Lab data from this composting mix contributed to this study as well.

Washington State University, encouraged by the potential of financial savings, started using composted material as bedding in the school’s dairy farm.  An unexpected benefit of this decision was the reduction of mastitis in the dairy herd.  The change in bedding was the only variable altered in the care of the herd when this observation was noted.  A study conducted by Cornell University’s Waste Management Institute studied the financial effects of using manure solids (DMS) as bedding.  This study showed an average of $37,000 was saved annually by the diary farms who switched to re-use bedding.  It was from these observations that we decided to apply the same questions to the equine industry. 

A study conducted by Caitlin Price Youngquist of the Snohomish Conservation District, and funded by Western SARE is searching for the health benefits to horses with the use of composted stable waste as bedding. Preliminary examination has shown an increase in foot and leg health and a decrease in thrush, scratches and dermatitis seen on the horses in the study.  General foot and leg health was also attributed to compost bedding by Dr. Hannah Mueller of Cedarbrook Veterinary Clinic and Northwest Equine Stewardship Center.  She documented relief for a horse with chronic hives and a horse with a tracheotomy.   The reduction of dust has been cited as a benefit to the horses suffering from heaves and other dust related ailments such as skin and respiratory irritations.  The compost material has the  unique quality of a large capacity for absorption while at an already higher level of moisture that makes the compost bedding less dusty. Both pellets and shavings exhibit this attribute.Youngquist’s assumption for the benefit composted bedding offers is based in the process itself.  She states, “The compost has been through a very hot phase to kill all pathogens and parasites. It now has a thriving microbial population that competes aggressively with the fungal and bacterial pathogens that cause infections and irritations on skin and hooves (similar to the concept of a pro-biotic).”

Stable waste compost as bedding can be used in its entirety or screened to collect the larger remaining pieces of shavings for bedding, leaving the fines for soil amendment. Testing has shown in either case the composted material to have high absorbency, more so than green shavings.  When mixed with 50% new or green shavings, the stall is at its most efficient for health and comfort for the horse.  The composted material offers higher absorption, soaking up the urine off the stall floor.  With a top dressing of new shavings the stall is aesthetically pleasing to the human eye, light in color and offering the horse a barrier to the wetter, compost material below.  The compost bedding is odor free when reintroduced to the stall.   The introduction of at least 50% new shavings also supports the ongoing composting system, refilling the system when it has its 40-50% reduction of volume and the eventual breakdown of the shaving pieces with multiple trips through the system.    Continuing research is being done to understand the effect of pelletized bedding used in the bedding re-use loop without the introduction of a larger substance to affect the integrity of the material as it continues to be re –used.

The first test done was to measure the absorption ability of the three types of bedding mixes.  Two inches of material was placed in a plastic container.  The first test done on 2” of green shavings, the second test done on 2” of a 50/50 mix of green shavings and compost, and the third test done on 2” of compost.  Each of the variations was weighed before the introduction of water.  One gallon of water was poured over the material and allowed to stand for 2 minutes.  The container was then drained of any standing water which was measured.  The container was again weighed in each case after the water had been drained.  This procedure allowed for the measurement of absorption by both the increase in weight and the volume of water not absorbed by the material.

The new shavings taken from a loose pile absorbed the least, the 50/50 mix the next higher amount and the compost bedding absorbed the most moisture.  This is impressive when one considers that the density of compost bedding is higher before the introduction of the test water.  The compost material is comprised of the same woody fiber as the shavings but the edges have softened and loosened, and it is possible that the breakdown of the resins, which can be hydro phobic, allows for additional absorption ability.

We also tested for the moisture content of each bedding type with a simple oven test.  The material was measured by a two cup measuring cup and poured into a glass baking dish.  The material was weighed before going into the oven, set at 200°.  The material was then weighed again to determine the moisture content after 12 hours.

These preliminary tests were performed to study initial benefits noted with bedding re-use.  These are not scientific studies and are only intended to show possible indications for the purpose of this paper and to encourage further study.  With composting and bedding re-use, barns close the waste stream loop and create a value added product.

What Have We Learned?

The viability of composted stable waste to be re-used as bedding is proven to provide financial benefits by saving  on the cost of material purchase and in the disposal of stable waste.  It provides  further savings in health care costs.

Laboratory Results for Composted Stable Waste

Laboratory Results for Composted Stable Waste

Laboratory Results for Composted Stable Waste
 

Future Plans

We will continue to support the Snohomish Conservation District study run by Caitlin Youngquist by supplying composted stable waste and collaboration. 

We plan to run our dust measurement during the summer months when we actually have dust in the Pacific Northwest. A furnace filter attached to the intake side of an 18” x 18” fan would be left on at ground level in a newly bedded stall for three minutes while the horse was hand walked around the stall.  This would be repeated for the three bedding variations.  The filter would be weighed before being attached to the fan and again after the three minute period.   

Study of pellets as bedding re-use material will be done, measuring the health benefits and the viability of the product over multiple uses.

A controlled trial on direct contact allergens will be conducted on the three bedding mixtures.

We will continue to educate the equine industry and encourage a broad scale adoption of this closed waste system.

Authors

Mollie Bogardus, MBA Sustainable Business, Equine Specialist, Green Mountain Technologies, Inc. and Michael Bryon Brown, President, Green Mountain Technologies, Inc.

Mollie Bogardus, mollie@compostingtechnology.com, Michael Bryon Brown, mbb@compostingtechnology.com

Additional Information

Bogardus, Mollie. “Equine Applications/Case Studies/ IOS  Ranch and Fort Myer/Henderson.” Green Mountain Technologies. Green Mountain Technolgies, Inc., n.d. Web. 15 Mar. 2013. http://compostingtechnology.com/equine/.

Cohen, Jamie. “Composted Horse Manure:  The Pros and Cons.” The Florida Horse Feb. 2013: 23. Print.

“Equine Applications.” Green Mountain Technologies- lab results. N.p., 12 Dec. 2012. Web. 1 Mar. 2013. http://compostingtechnology.com/equine.

LeaMaster, Brad, James R.  Hollyer, and Jennifer L. Sullivan. “Composted Animal Manures: Precautions and Processing.”   Cooperative Extension Service,College of Tropical Agriculture and Human Resources, University of Hawai‘i. University of Hawaii at Manoa, n.d. Web. 6 Mar. 2013. http://www.ctahr.hawaii.edu/oc/freepubs.

Price Youngquist, Caitlin. “Composted Horse Manure and Stall Bedding Pilot Project – YouTube.” YouTube. Snohomish Conservation District, 17 Jan. 2013. Web. 1 Mar. 2013. https://youtu.be/B91U5UjuaXI.

Schwartz, Mary, Jean Bonhotal, and A. Edward Stachr. “Use of Dried Manure Solids as Bedding for Dairy Cows.” Cornell Waste Management Institute. Cornell University, n.d. Web. 1 Oct. 2012. http://cwmi.css.cornell.edu>.

Wheeler, Eileen , and Jennifer Smith Zajaczkowski. “Horse Stable Manure Management.” Cornell Cooperative Extension, Orange County Equine, Saratoga County Equine. Penn State University, n.d. Web. 6 Mar. 2013. http://cceequine.org.

Zaborski, Ed. “Composting to Reduce Weed Seeds and Plant Pathogens – eXtension.” eXtension – Objective. Research-based. Credible.. University of Illinois at Urbana Champaign, 22 Oct. 2012. Web. 2 Oct. 2012. http://www.extension.org/pages/28585/composting-to-reduce-weed-seeds-and….

Acknowledgements

This report could not have been done without the support of Philippe Le Dorze at IOS Ranch.  His interest and pursuit of knowledge pushed us to continue to search for improvements and greater knowledge.

The staff at Joint Base Myer/Henderson, Amy Fagan especially, were also willing participants in the pursuit of the perfect compost recipe.  Paul Brezovec at Concurrent Technologies Corp was a tremendous support to the project and continues to encourage the use of Earth Flow vessels for other bases.

A special thanks to Caitlin Price Youngquist for her ongoing dedication, collaboration and interest in the phenomena of bedding re-use.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Measuring Greenhouse Gas and Nitrogen Gaseous Losses When Comparing Bulking Agents Used to Compost Separated Hog Solids

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Why Study Composting Separated Manure Solids?

This research is evaluating management options for conventional hog producing facilities in regions of Manitoba that will have insufficient land base for sustainably applying raw slurry manure when manure application regulations switch from nitrogen based to phosphorus based rates. Producers are being encouraged to use solid-liquid separation, such as centrifugation, to remove the phosphorus rich solid fraction so that it can be transported and applied further away where there is a phosphorus deficiency. However, the resulting separated hog solids (SHS) product is still odorous and prone to nitrogen losses through ammonia volatilization. Therefore, it has been suggested that composting the SHS before it is applied is a beneficial management practice that would allow producers to capitalize on agricultural and environmental benefits such as reduced odours, stabilization of minerals, application of a homogeneous product, and acts as a multi-beneficial soil conditioner. However, the low starting C:N of 15:1 and small particle size of SHS make it a unique and challenging product to compost in windrows, a common form of large production on-farm composting. The SHS must be combined with a bulking agent that allows adequate nutrient balance for decomposition as well as a porous structure. Therefore, this project is comparing wood shavings (WS) and wheat straw (WHT) as bulking agents to evaluate which is the better management practice based upon minimizing greenhouse gas emissions and additional nitrogen gas losses as well as overall quality of the mature compost. 

LI-8100a automated flux chamber

What Did We Do?

Starting in October 17, 2012 we created two windrows containing SHS, one with wood shavings as a bulking agent and one with wheat straw. The materials were mixed in a feed mixer to produce a homogeneous mixture with the initial starting parameters shown in Table 1. The windrows were turned once a week for the first four weeks with a Backus windrow turner.

Gas emissions were measured with the use of the highly innovative technology of the LI-8100a automated chamber system (LICOR BioSciences) and Fourier Transform Infrared spectroscopy (FTIR) multi-gas analyzer (Gasmet DX4015). By combining these two instruments it has the advantage of nearly continuous unattended data collection and simultaneous measurement of greenhouse gases (carbon dioxide, methane, nitrous oxide) and additional nitrogen gases (ammonia, nitrous dioxide, and nitrogen monoxide). There were four automated chambers on each windrow; a flux measurement was taken every half hour, alternating between the two windrows. Flux emissions were calculated using linear regression analysis.

Table 1. Initial starting parameters for the two windrows

Initial In-process Compost

Starting C:N

Starting Moisture %

Starting Bulk Density (kg/m3)

Starting pH

WHT + SHS

32.5

63.70

170.5

6.86

WS + SHS

35.5

60.45

350

6.5

The temperature, % oxygen, and moisture content of the windrows were recorded to identify when the compost needed to be turned and to track the composting process and relate it to the gases emitted.

Backhus compost windrow turner

What Have We Learned?

In September 2011 we conducted a trial that used straw as a bulking agent but found the contact between the separated hog solids and straw was poor due to the difference in particle size allowing for large pore spaces and the waxy texture of straw. The porous structure made it difficult to maintain moisture in the compost windrow and when water was added some of the separated hog solids actually “washed off”.  In the winter, the windrow wasn’t big enough or it was too porous that it did not insulate well so self heating stopped and the pile froze in January. These problems slowed the decomposition process and resulted in compost with straw pieces still visible.

For this trial we decided to try using wood shavings as an alternative bulking agent, because wood shavings have a smaller particle size which we predicted would result in better contact with the separated hog solids and a less porous structure allowing better insulation against the weather (water loss in the summer, heat loss in the winter). Additionally, it is expected that wood shavings are also beneficial in reducing ammonia losses.

However, during this trial we experienced much wetter and cooler conditions compared to the year before, so we did not have to add water to the windrows. This was beneficial for the windrow with straw because the moisture content did not decline resulting in a steady rate of decomposition during the first month of composting noted by continuous CO2 emissions. Eventually the moisture content became too high creating anaerobic conditions and the production of CH4 after the second and fourth turnings. NO2 emissions were also detected during the same time as CH4, indicating some aerobic respiration occurring. After CO2 emissions reduced there was a small amount of N2O and NO measured.

The windrow with wood shavings took a little longer to start producing CO2 because it became anaerobic from the start. CH4 was produced much early and at higher emission rates compared to the windrow with the straw as a bulking agent. N2O, NO, and NO2 were emitted at the same time as CH4, indicating there were anaerobic and aerobic pockets throughout the windrow. N2O emissions continued after CO2 emissions declined.

Composting in the winter

After the windrows had been in the active stage of composting for three months, the temperature within the windrows gradually declined and both windrows froze up in early January.

We are currently in the process of calculating the ammonia flux determinations. Due to the nature of ammonia it is prone to absorbtion reactions on the surface of the LI-8100a and FTIR systems’ tubing. The surface reactions cause a time delay for the FTIR to analyze the concentration compared to the other gases. Thus, this gas requires a different time interval to calculate the flux.

Future Plans

A common problem with using chamber measurements on compost windrows is underestimation of gas emissions from chambers placed on the top of the windrow when high winds blow through the windrow horizontally, reducing the “chimney effect”. Having the ability to collect gas emission data at such a high frequency using the LI-8100a automated chamber and FTIR system allows us to identify when gases emissions may be underestimated due to wind. The next step is to determine if we can correlate the wind speed and direction with under estimation of gas losses.  

Authors

Jolene Rutter, MSc. Candidate, University of Manitoba, Jolene_rutter@hotmail.com

Mario Tenuta, Canada Research Chair in Applied Soil Ecology, University of Manitoba

Matt Gervais, Soil Ecology Field Technician, University of Manitoba

Acknowledgements

Western Economic Diversification Canada, Manitoba Pork Council, Manitoba Horticultural Productivity Enhancement Centre, Manitoba Rural Adaptation Council, NSERC, National Center for Livestock and the Environment, University of Manitoba Soil Ecology Laboratory, Glenlea Research Farm, Prairie Agricultural Machinery Institute, Compo-stages, Puratone

 

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