TABLE OF CONTENTS

Section 1 -The Basics................................................................................... 1

...... What is Compost?............................................................................ 1

...... why compost?.................................................................................1

...... How Does it Work?.......................................................................... 1

...... HOW LONG DOES IT TAKE?................................................................ 2

...... HOW MUCH WILL IT COST ME?......................................................... 2

...... HOW WILL I KNOW IF COMPOSTING CAN WORK FOR ME?....... 2

...... References.......................................................................................... 3

Section 2 - Benefits of On-Farm Composting............................... 4

...... Soil Conditioning........................................................................... 4

...... Improved Waste Handling.......................................................... 4

...... Improved Land Application....................................................... 4

...... REDUCED WASTE DISPOSAL COSTS................................................. 4

...... Lower Risk of Pollution and Nuisance Complaints.... 4

...... Pathogen Destruction................................................................. 5

...... Disease Suppression....................................................................... 5

...... Bedding Substitute for Farm Animals.................................. 5

...... Saleable Product............................................................................ 5

...... SOME OF THE DRAWBACKS............................................................... 6

Section 3 - Composting Operations................................................... 7

...... STEP 1 - FEEDSTOCK PREPARATION................................................ 7

...... step 2 - COMPOSTING......................................................................... 7

...... STEP 3 - CURING.................................................................................... 8

...... STEP 4 - SCREENING............................................................................. 9

...... STEP 5 - STORAGE................................................................................. 9

Section 4 - Methods of Composting................................................. 10

...... Turned Windrow............................................................................ 10

...... Aerated Static Pile (Individual AND EXTENDED).............. 11

...... Summary of Composting Processes.................................... 12

Section 5 - Composting Equipment................................................... 15

...... Front-End Loaders....................................................................... 15

...... Grinders and Shredders............................................................ 16

...... Mixers / Manure Spreaders....................................................... 17

...... Windrow Turners.......................................................................... 18

...... ScreenING EQUIPMENT................................................................... 18

...... STACKING Conveyors................................................................... 19

Section 6 - Site and Environmental Considerations........... 21

...... Regulatory Compliance Issues.............................................. 21

...... Siting an On-Farm Composting Facility............................ 21

...... Separation Distances................................................................. 22

...... Drainage Requirements............................................................. 22

Section 7 - Compost Quality................................................................. 24

...... Moisture Content......................................................................... 24

...... Nutrient Content......................................................................... 24

...... Particle Size Distribution......................................................... 24

...... Stability............................................................................................. 24

...... Content of Other Elements..................................................... 25

...... PRODUCT CONSISTENCY OVER TIME............................................ 25

...... Pathogen Reduction Criteria................................................. 25

Section 8 - Marketing Agricultural Compost......................... 26

Section 9 - Regulatory Approvals and Permits....................... 28

Appendix A - Glossary of Composting Terms............................. 29

Appendix B -.. Cost Estimate for Aerated Static Pile Composting Pilot Test  33

APPENDIX C - DEPT. OF ECOLOGY INTERIM COMPOST QUALITY    GUIDELINES..........................................................................                              34

SECTION 1  -  THE BASICS

WHAT IS COMPOST?

Compost is a nutrient rich soil-like material created by the biological decomposition of organic materials such as vegetative debris and livestock manures.  Compost can improve soil fertility, extend fertilizers, save water, suppress plant diseases, and boost soil tilth.  Composting manures can improve manure handling and help to reduce their environmental impacts.

WHY COMPOST?

Because farming itself involves the efficient management of a variety of natural processes, in many ways, composting is a natural fit for the farmer.  Composting is the efficient management of the biological decomposition of organic matter.  Ideally,  the basics required for compost are readily available on the farm:   feedstocks to be composted, such as livestock manure or crop residues; readily available bulking materials to thicken feedstocks, such as sawdust; and air, water, space and time.  Microorganisms already present in the feedstock break down the material to a stable, beneficial product, free of pathogens and plant seeds.   

On-farm composting requires some effort, but it can work for you.

HOW DOES IT WORK?

Composting is most commonly an aerobic process, that is, the biological breakdown of the materials takes place in the presence of oxygen (air).  The main byproducts of the breakdown are carbon dioxide, water and heat. Composting can also be an anaerobic process, where breakdown occurs in the absence of oxygen.  In this case, the main byproducts are methane, carbon dioxide, and various low organic acids and alcohols.  Since aerobic composting is more efficient and presents fewer undesirable byproducts, this workshop will focus on aerobic composting.

The basic process of composting includes the following five steps:

·        Feedstock Preparation
·        Composting
·        Curing
·        Screening
·        Storage

In a nutshell, feedstocks and any required bulking agents are mixed together in suitable proportions and spread into rows or piles.  Air and water are added to the piles in appropriate amounts while the microorganisms in the mixed materials begin to eat and process the nutrients in the feedstock.  This phase of composting, which is the most active, lasts about a month and generates temperatures high enough to kill pathogens and weed seeds.  When this stage is complete, the compost may be moved to a separate pile and allowed to cure for an additional two months.  While curing, biological activity in the compost is still taking place, but at a much slower pace than in the active phase.  After curing, the compost may be screened to create a  more uniform size, remove rocks and uncomposted materials, and to recover some types of bulking agents for reuse.  The compost should then be stable, that is, it should have a fairly consistent look and an earthy, inoffensive odor.  It can then be stored for use on the farm or put up for sale in bulk or bag. 

That was the short version.  These steps, plus the “nuts and bolts” of the machinery that can be used and information on rules and regulations, are explained in more detail in the following sections.   Also, most of the “buzzwords” associated with composting, are defined in a detailed glossary  which can be found in Appendix A.

HOW LONG DOES IT TAKE?

Your time investment:   Composting will require time and effort on your part.  Your biggest time investment will be the initial set-up of the composting facility, which will vary from farm to farm, depending upon the size of the facility you plan, the method of composting you choose, the site preparation work required, and the equipment available to you.  Set-up time can range anywhere from a few weeks to several months. 

 Once your composting operation is up and running, typical time investment for a routine operation can range from  4 to 16 man-hours per week.

Nature’s time investment:  The time it takes from initial ingredient mixing through curing to the point of a stable product ranges from 60 to 120 days; 90 days is a good rule of thumb.  But since composting is a continuous process, beyond that initial 90 days or so,  you should always have some compost ready for use.

HOW MUCH WILL IT COST ME?

The costs for setting up a composting operation will vary with your site, the size of your composting operation, the method of composting you choose, and the type of  machinery you already have available.   A typical cost range, assuming a composted volume of  no more than 500 cubic yards per year, a small (30’ x  80’)  site,  use of the aerated static pile composting method discussed in this manual, and ownership of a front-end loader, is from $1000 to $1500.   Detailed costs and materials for a somewhat larger on-farm set-up are shown in Appendix B. 

HOW WILL I KNOW IF COMPOSTING CAN WORK FOR ME?

Composting is as much an art as it is a science.  One learns to compost much the way one learns to farm - by doing.  The fundamentals of composting are easy to grasp and implement, especially if a person discovers they have a true interest in the subject.  Composting, as with farming, requires a spirit of trial and error to develop “know-how” and experience.  While there are many wrong ways to compost, the “best way” to compost depends on many factors, including availability of land, equipment, and start-up capital. 

Experience shows that small and medium sized composting trials are invaluable for developing this know-how while minimizing downside risks.   Much can be learned by conducting small trials using various mixes of feedstock materials and composting techniques, during the different seasons of the year.  A great deal can also be learned by visiting other composting facilities and talking with operators about their methods and experiences.

REFERENCES:

There are numerous references, parts of which have been incorporated into this document, that are readily available to the composter to assist him or her with operations start-up, process monitoring, marketing of the finished products, and virtually every other aspect of compost operation. The following selected references include periodicals, handbooks, engineering texts, and pertinent bodies of state and federal regulations:

·        BioCycle, Journal of Waste Recycling, J.G. Press, Inc.  419 State Avenue, Emmaus, PA  18049 (215) 967-4135.

·        On-Farm Composting Handbook, Northeast Regional Agricultural Engineering Service, NRAES-54, June, 1992, 152 Riley-Robb Hall,  Cooperative Extension, Ithaca, NY  14853-5701, (607) 255-7654

·        The Practical Handbook of Compost Engineering, Robert T. Haug, 1993,  Lewis Publishers, CRC Press, Inc., 2000 Corporate Blvd., NW Boca Raton, FL  33431

·        Minimum Functional Standards for Solid Waste Handling, WAC 173-304

·        Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503

·        Interim Guidelines for Compost Quality, Washington State Department of Ecology Publication #94-38, April 1994.

SECTION 2 - BENEFITS OF ON-FARM COMPOSTING

This section discusses several of the benefits of composting, as well as some potential drawbacks to be considered .

SOIL CONDITIONING

Compost is an excellent soil conditioner.  When applied to cropland, compost adds organic matter, improves moisture retention (drought tolerance) and soil structure, reduces fertilizer requirements and reduces the potential for soil erosion.

IMPROVED MANURE HANDLING

Composting reduces the weight, moisture content, odor, and vector-attracting qualities of manure and other farm generated organic waste materials.  Compost is easier to handle than manure and stores well without odors or fly problems.  Because of its storage qualities, compost can be applied at convenient times of the year. 

IMPROVED LAND APPLICATION

Both compost and raw manure are good soil conditioners with some fertilizer value.  However, there are benefits to be gained by composting manure.

·        Composting converts the nitrogen contained in manure into a more stable organic form.  Although this results in some loss of nitrogen, the nitrogen that remains is less susceptible to leaching and further ammonia losses.

·        Highly bedded manures have a high carbon-to-nitrogen ratio, and when applied to the land directly, the excess carbon in the manure causes nitrogen in the soil to be temporarily unavailable to the crop.  Composting high-carbon manure/bedding mixtures lowers the C : N ratio to acceptable levels for land application.

·        The heat generated by the composting process reduces the number of weed seeds contained in the manure, resulting in a significant reduction of weeds over several years of application.

REDUCED WASTE DISPOSAL COSTS

Composting can reduce the volume of on-farm organic waste that may have previously gone to the landfill, thus avoiding a tip fee for those materials.

LOWER RISK OF POLLUTION AND NUISANCE COMPLAINTS

On a growing number of farms, manure is more of a liability than an asset.  Disposal of manure is a problem where feed is not grown on the farm, when previously rented land is lost, or when herd size has increased beyond the farm’s capacity to support it.  Odor complaints are common in populated areas.  Other concerns include runoff from manure spread in excessive amounts or on frozen ground, and nitrate contamination of wells and bodies of surface water.  Composting can alleviate these problems.

PATHOGEN DESTRUCTION

Maintaining pile temperatures in excess of 55^oC (131^oF) for a period of 3-days will destroy pathogens that can be problematic for both humans and farm animal.  The Aerated Static Pile (ASP) method of composting, discussed in Section 4, is capable of accomplishing this in a relatively short period of time because the 12 to 18-inch thick cover of finished compost material enables this temperature to be maintained throughout all of the newly composted material.

DISEASE SUPPRESSION

Properly prepared compost has been found to reduce soilborne plant diseases without the use of chemical controls.  The disease suppressing qualities of compost are believed to result partly from a more complex and competitive environment of soil microorganisms. 

BEDDING SUBSTITUTE FOR FARM ANIMALS

Compost has been used for poultry litter and bedding in livestock barns.  Research and experience have shown that compost is generally a safe and effective bedding material.

SALEABLE PRODUCT

One of the most attractive features of composting is that there is a market for the product.  Potential buyers include home gardeners, landscapers, vegetable farmers, turf growers, operators of golf courses, and ornamental crop growers.  In addition, there are numerous applications in the construction industry.  In this instance, a disposal problem has been converted into a revenue stream.

SOME OF THE DRAWBACKS...

In addition to the benefits of on-farm composting, there are several drawbacks which must also be considered, such as time and money, odor production,  weather, marketing, and diversion of manure and crop residues from cropland.

TIME AND MONEY

Like any additional on-farm operation, composting requires equipment, labor, and management.  The initial investment for a composting operation can be very low, if existing farm equipment and facilities are used.  This approach is fine where the volume of material is relatively small (<  500 CY/year), but most medium (2000 - 4000 CY/year) to large (4000+ CY/year) scale farms have found that using only existing equipment requires too much labor.  Many farm composters have found it necessary to purchase dedicated composting equipment.  With special equipment, it could cost as little as $10,000 or well over $100,000 to start a farm composting operation, depending on the composting technology that is selected.

LAND

The area required for the composting site, storage for raw materials, and storage for the finished compost can occupy a considerable amount of land, and sometimes, building space.

ODOR

Composting operations inevitably produce some odor, and if the operation is mismanaged, the odors can be offensive and may generate complaints from nearby residents and passersby.  That’s why it’s important to develop and maintain good neighbor relations with those in proximity to your composting site.   This means maintaining an awareness of how odors from your operation impact others.  A continual and conscientious effort toward odor control is essential for your composting operation to be successful. 

Offensive odors can be minimized through proper process controls and good housekeeping procedures.  In most cases, the odors from a well-managed composting operation are periodic and short-lived, and in cases such as manure handling, represent an improvement over conventional handling methods.  

WEATHER

Cold weather may slow the composting process by lowering the temperature of the composting material.  The effects of rain and snow are potentially more serious.  Heavy precipitation adds water to the composting mix and can impede or stop the composting process altogether.  Excessive rain can also create a serious leachate (contaminated water) handling problem.

MARKETING

Selling compost involves marketing, which means searching out potential buyers, advertising, packaging, managing inventory, matching the product  to the customer desires, and maintaining consistent product quality.

DIVERSION OF MANURE AND CROP RESIDUES FROM CROPLAND

Selling farm-composted manure and/or crop residues diverts the nutrients, organic matter, and soil-building qualities of those materials from the cropland.   Buying commercial fertilizers to make up for the lost nutrients may not make good economic or agronomic sense.

SECTION 3 -  COMPOSTING OPERATIONS

The five basic steps to the composting process, as mentioned in the introduction, are now discussed in a bit more detail below.

STEP 1.  FEEDSTOCK PREPARATION

Feedstocks (or organic materials to be composted) are mixed with bulking agents and/or feedstock amendments to provide a mixture suitable for composting

·              Bulking agents are added to provide porosity and structure to the compost mix, and  adjust the moisture content to within a desirable range, which helps create an environment in which the biological decomposition essential to composting can take place over time.

·              Common bulking agents include:  wood chips or shavings, sawdust, recycled compost, and shredded yard debris, all of which can be processed and stockpiled until needed. 

·              Some bulking agents, such as sawdust, become an integral part of the compost and cannot be separated out at the end of the process, while others, such as shredded tires, can be recovered and used again in the next batch.

·              Feedstock amendments can provide a source of required nutrients, such as carbon.  Some additives, such as wood chips, can act as both a bulking agent and an amendment, but each has a specific purpose and must be used appropriately.

·              “Recipe mixes”  or appropriate ratios of feedstock to bulking materials can be developed over time for your particular feedstocks.  These mixes are determined by conducting a composting mass balance evaluation in which the carbon, nitrogen, and moisture content of each compost ingredient is evaluated, and the proportion of bulking or amendment material to reach the target carbon-to-nitrogen (C:N) ratio and moisture content is determined.

STEP 2.  COMPOSTING

After the feedstock has been prepared, the mixture is formed into rows or piles, and composting can begin. Active composting generally occurs over a period of 21 to 28 days.

Composting represents the combined activity of a various bacteria, actinomycetes, and other fungi associated with a diverse succession of environments.

Moisture, temperature, pH, nutrient concentration and availability, and oxygen concentration are principal factors which affect the biology of composting.  These factors are discussed below.

·              Moisture:   The optimum initial moisture content is 50% to 60% (total solids equals 100% minus the moisture content).

·              Temperature:  The majority of  microorganisms associated with composting operate within one of two temperature ranges: the mid-range (mesophilic) from 50 - 105 ° F and the high-temperature (thermophilic) range from 105 - 160 +°F.  Temperatures beyond 160°F cause most microorganisms to either die or become dormant which slows the composting process. These higher temperatures are also associated with generation of offensive odors.  Thermophilic temperatures are most efficient and effective for composting.  (Most weed seeds are destroyed at 145°F.)   

Temperature must be carefully watched and adjusted as needed throughout the composting process.  Aeration, discussed in Section 4, is the most effective way to maintain desirable temperatures.

During the winter months, suitable temperatures can be maintained by increasing the pile size and providing a cover of finished compost over the compost mix. 

·              pH:  Although the pH varies throughout the pile and throughout the composting operation, the pH of the finished compost is generally within a range of 6.5 to 7.5. While the optimum pH range is 6.0 to 7.5 for bacteria and 5.5 to 8.0 for fungi, control of pH for optimum operation is difficult and is generally not attempted.

·              Nutrient Concentration:  Biodegradable carbon and nitrogen are required as energy sources.  Carbon-to-nitrogen (C:N) ratios between 25 and 35 provide the best conditions.  Lower C:N ratios increase the loss of ammonia by volatilization, and higher ratios lead to longer composting times.  No other macronutrients or trace nutrients have been found to be impede the rate of composting.

·              Oxygen Supply:  An oxygen concentration of at least 5 percent by volume in the composting mix  is generally required to ensure continuous aerobic conditions.  However, increasing the oxygen concentration beyond 15 percent (by adding air) may result in a temperature, decrease because of the increased air flow.   Therefore, temperature monitoring in conjunction with oxygen monitoring is recommended.

STEP 3.  CURING

Following active composting, the processed materials are cured for a minimum of one month, and preferably, two or three months.

·              The composting process continues throughout the curing phase, but at a slower rate and at lower temperatures.   Curing creates a more stable compost and greatly reduces the potential for plant phytotoxicity.

·              The moisture content of the compost mix during curing should be maintained at between 50 and 60 percent.  Following the curing phase and prior to screening, the moisture content should be reduced to approximately 40 to 45 percent to facilitate screening and recovery of bulking materials.

STEP 4.  SCREENING

·              Screening of the materials is normally accomplished to produce the fine, uniform texture desired for the final product, and to recover the bulking material for reuse in the composting process.  Screening is not necessary with certain (fine) bulking agents.  Screening can be accomplished either before or after curing.

STEP 5.  STORAGE

·               Stable compost can be stored under cover for several months, without the risk of spoilage.  Suitable storage is important because compost use typically peaks in the spring and fall months, moderates through the summer and virtually ceases in the winter. 

·               Stored compost should be kept dry, to maintain product quality and minimize potential surface water contamination.  This can be accomplished by covering the compost with tarps or by storing it under a roofed structure.

SECTION 4 - METHODS OF COMPOSTING

One method of composting will probably suit your circumstances better than another.  The following three technologies seem to work best for on-farm composting:

          Turned Windrow

          Aerated Static Pile (Individual)

          Aerated Static Pile (Extended)

These technologies are described below, followed by a discussion of  some of the advantages and disadvantages of each.

TURNED WINDROW COMPOSTING

With the turned windrow composting process, the mixture to be composted is stacked in long parallel rows separated by alley-ways for equipment access.  The cross-section of the windrows may be trapezoidal or triangular, depending largely on the characteristics of the equipment used for turning the piles.  The width of a typical windrow ranges between 8 and 18 feet, and