On-Farm Composting I

In my On-Farm Composting Workshops, I am often asked excellent questions about the "ins and outs" of composting. Many of these questions can be answered in a variety of ways, especially considering the number of variables that must be managed asset, combined with the uniqueness of each and every farm. The following frequently asked questions and answers provide a general overview of the topics that I will cover in future articles in this On-Farm Composting Series.

Composting, in the broadest sense, is simply the biologic breakdown of organic matter. Composting is a spontaneous process and has been going on since the origin of carbon based life on this planet.
In a modern context, Composting is more closely defined as the controlled biologic breakdown of organic matter under aerobic conditions. With on-farm composting, organic matter includes manure of any variety, bedding material, waste silage, produce, bulbs, etc. The term aerobic simply means in the presence of oxygen (air). The key word in this definition is controlled, which means the operator can adjust the process to obtain a desired finished product, within a optimal period of time.

There are several methods of composting, each of which can be successfully used at a municipal/ commercial setting or on-farm. How-ever, composting in an agricultural setting has many distinct advantages, some of which include the following:

* Permits are comparatively easy to obtain, if in fact permits are required at all.
* Leachate (impacted water) from the compost pile is easily managed by pumping into a storage lagoon. Leachate management at municipal facilities is often difficult and very costly.
* Existing farm equipment can be used to accomplish much of the composting process. The most costly equipment typically includes a front-end loader and manure spreader.
* Land is generally available for setting up the composting facility (including future expansion) and the area for storage of finished products.
* Cost share money is often available for capital improvements through Permits from the Natural Resource Conservation Service (NRCS).

There are many advantages of composting organic waste on-farm, a few of which include the following:

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 volume, moisture content, odor and vector (flies) attracting qualities of manure and other farm generated organic waste materials.

Improved Land Application- composting converts the nitrogen present in the waste materials into a more stable form, which is released slowly over a period of years and thereby not lost to the environment. In addition, the heat generated during the composting process destroys both weed seeds and pathogens present in the waste.

Lower Risk of Pollution and Nuisance Complaints-On a growing number of farms, manure is more of a liability than an. Odor complaints, which are common in populated areas, can be significantly reduced by composting properly. Composting can also alleviate problems associated with ground water and surface water contamination.

Bedding Substitute for Farm Animals-Compost has been successfully used for poultry litter and bedding in livestock barns.

Saleable Product-One of the most attractive features of composting is that there is generally a ready market for the product. Potential buyers include top soil mixers, nurseries, home gardeners, landscapers, vegetable farmers, ornamental flower growers and golf courses.

Start with the Finished Product in Mind-The finished product specification will determine the selection of feedstock materials, method of composting, and post-composting operations such as screening and aerated curing.

Learn from Other People's Mistakes-There is a wealth of knowledge in the composting world, much of which has been gained by solving problems. Much time and money can be saved by paying attention to these lessons. Visit as many composting facilities as possible and talk with the operators. As long as you are not a regulator, they will generally be pleased to discuss their experiences.

Start Small and Grow in Planned Stages-First, learn the composting process in a small scale because any mistakes that are made can be easily corrected, with little impact to neighbors and to the environment. Grow in planned increments to maintain control and to demonstrate stability in the operation.

Treat your Neighbors as Allies, not Enemies-The most common reason for facility closure is complaints from neighbors, generally arising from odors. These can be controlled, however, short term problems may arise and it is much better to have the neighbor discuss the situation with you than to have them contact the local health district or air quality board. Your neighbors can also be your allies when it comes to product marketing. Give them some product to try, and the word will spread.

By Peter Moon, P.E. Consulting Engineer and On-Farm Composter Price-Moon Enterprises Snohomish, Washington For more information on the subject of On-Farm Composting, contact PriceMoon Enterprises, 10221 159th Ave. SE, Snohomish, WA 98290, Phone: 360/568-0146, e-mail: pricemoon@aol.com.

By Peter Moon, P.E.
Consulting Engineer And On-Farm Composter,
Price-Moon Enterprises, Snohomish, WA

Composting is as much an art as it is a science. As with farming, composting requires a spirit of trial and error to develop "know-how" and experience. While there are numerous methods of composting, three methods are best suited for most on-farm applications because of their relative simplicity and use of existing farm equipment. These include the "PHD", turned windrow, and aerated static pile methods of composting.

Piled Higher and Deeper (PHD) composting is the oldest and most common method of composting, (as well as the most problematic). With this method, the feedstock materials are simply stacked and left to decompose for an extended period of time.

While it is clearly the least expensive method, it does not meet the current definition of composting, which is "the controlled biologic breakdown of organic matter under aerobic conditions". Because of the size of most PHD piles, this method certainly can not be considered a controlled, aerobic process. A PHD compost pile is often a source of offensive odors, and typically produces an inferior finished product, full of weed seeds.

With turned windrow composting, the feedstock materials are 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 the height ranges between 4 and 7 feet. The length of the pile is determined by the size of the composting site.
Compost windrows may be turned with conventional front end loaders or with specialized windrow turning equipment. This technology is best suited to small facilities when relying on front end loaders for windrow turning. It is not well suited to medium and large scale facilities because of the cost of equipment operation and maintenance.

The turned windrow process is generally conducted in uncovered areas and relies on natural ventilation and frequent mechanical mixing of the piles to maintain semi-aerobic conditions. Numerous studies have shown that oxygen levels within the pile drop to less than 5 percent within 30 to 60 minutes after turning, thereby resulting in anaerobic conditions. As a result, offensive odors can be emitted when the pile is next turned. It is also difficult to maintain desired temperatures within the pile, as the pile cools each time it is turned and the recovery time increases as the compost material ages.

Turned windrow composting generally produces a quality product, free of animal pathogens and weed seeds. This is particularly true when the initial feedstock materials include coarse bulking agents that need to be mechanically broken down prior to use and/or sale.

Advantages of the turned windrow composting process include thorough mixing of materials, mechanical break-down of the larger bulking materials that will not be recovered for reuse, and wide selection of windrow turners at competitive prices. Along with anaerobic pile conditions and potential odor problems, the main disadvantage with a turned windrow system is a comparatively large land area requirement, and increased surface water management.

The aerated static pile (ASP) method of composting was developed in the mid-1970's to reduce land area requirements and to resolve other problems associated with the turned windrow method. Two distinct methods of aerated static pile composting have been developed and include the individual ASP and the extended ASP methods.

With the individual ASP method, the compost mix is constructed over perforated pipes, oriented parallel the centerline (length) of the pile. Individual piles may be on the order of 20 feet wide, 75 to 100 feet long, and upwards of 10 to 12 feet high. As with turned windrow composting, an alleyway is generally left between the piles for equipment access.

Following construction of a new pile, the fresh compost material is covered with a 1-foot thick layer of finished compost for insulation and odor control. Throughout the composting process, air is forced (positive aeration) or drawn (negative aeration) into the pile using an electric blower. When the pile is broken down, the aeration pipe may be recovered, as with thick wall PVC, or sacrificed, as with ADS drainage pipe.

The extended ASP system was developed to make more effective use of available space. With this method, adjoining piles (cells) are constructed directly on the flanks of the preceding piles, thus forming a broad pile with a flat top. Several perforated air pipes may be connected to a larger diameter header pipe which is fed by a high volume, high pressure blower. In this configuration. the volume of compost material per square foot is approximately 3 to 4 times that of the individual ASP method, and upwards of ten times that of the turned windrow method.

The main advantage with the ASP method is that it provides for more flexible operation and more precise control of oxygen and temperature conditions in the pile. Since the time required for composting tends to be shorter and anaerobic conditions can be more readily prevented, the risk of excessive odor generation is significantly reduced. In addition, the finished product is free of pathogens and weed seeds.

The primary disadvantage associated with the ASP method are that the coarse materials are not mechanically broken down and the compost inside the pile can dry out, resulting in a reduced rate of decomposition. The first problem can be resolved by screening the product, if needed for retail sales. The problem drying can be managed by proper moisture conditioning of the initial mix, and by adjusting the frequency and duration of air flow.

Currently, much of the interest in the ASP composting method is centered on municipal wastewater biosolids. However this interest is gradually spreading to other feedstock materials, including yard waste and pre-consumer food waste. At the present time, ASP composting is still very new to agriculture. This is because the need to manage farm manure and other organic residuals has only recently become a critical issue in the public eye. Given that the ASP method is both very practical and cost effective, it will very likely become common practice in the next 5 to 10 years.

For more information on the subject of On-Farm Composting, as well as training services offered by Price - Moon Enterprises, contact Peter Moon at 10221 159th Ave. SE, Snohomish, WA 98290, Voice 360/568-0146, e.mail: pricemoon@aol.com.

To take full advantage of com-posted organic waste materials, the composting process must be designed to produce a high quality product. This is true for both field application and retail sale of the finished compost materials. Compost quality is measured by several criteria, including the following:

Pathogen Reduction
Compost produced from agricultural waste is not regulated, and is therefore not required to comply with the pathogen reduction criteria that is stipulated for municipal sludge (bio-solids) compost [EPA 503 Regulations]. However, compliance with these criteria is good practice and may be stipulated if a site permit is required for non-farm organic waste materials. The compost product should fulfill the following criteria:
* The compost product should be brought to a minimum temperature of 55oC (130oF) for three consecutive days using the Aerated Static Pile (ASP) method of composting, or 15 consecutive days with 5 turnings using turned wind-row composting. These methods are discussed in Part II - Three Methods of On-Farm Composting, February 1997. These conditions are termed the Process to Further Reduce Pathogens, or simply PFRP.
* The compost product should be exposed to a minimum composting period of 30 calendar days with ASP composting, and 45 days with turned windrow composting, followed by a minimum curing period of 30 calendar days prior to distribution.
* Monitoring of the compost for pH, percent total solids, volatile solids reduction, nutrients, and heavy metals concentration should be done on a quarterly basis, and more frequently if there is much variation in feedstock materials.

Stability
The term "stability" is a relative measure of decomposition. A stable compost will not undergo additional rapid decomposition, reheat significantly when piled, or produce nuisance odors when applied by end users. If the compost has undergone the adequate composting and curing procedures, there should be no problem in producing a stable product. Assuring a minimum curing period of 30 days is important to produce a stable compost product.

Nutrient Content
The nutrient content of compost is also a measure of quality. The major plant nutrients supplied by compost are nitrogen, phosphorus, and potassium. Most minor plant nutrients are also contained in compost and these also contribute to its quality. The level of nutrients in compost is controlled by the chemical composition of the initial feedstock materials and the composting process. While not a fertilizer (typical NPK ~ 1,1,1 or less), compost is often used as a slow release fertilizer supplement.

Moisture Content
The moisture content of the finished compost product is controlled by storing the compost so as to avoid significant moisture addition by rainfall. The product must be dry enough for land application using conventional loading, hauling and spreading equipment. A moisture content of 45 % (equivalent to 55 % solids content) is a desirable target. During the rainy season, these moisture levels can be maintained by storing finished product under a roof or tarps. In many cases, excess moisture can also be driven off by providing additional air flow through an aerated static pile. In arid climates and during the dry months of the year, a cover is generally not necessary.

Particle Size Distribution
The range of particle sizes is primarily a function of the initial feedstock materials, whether or not the product is screened, and the screen size used. On-farm use is more forgiving than commercial distribution, and in many cases, screening will not be required for field application. Retail End users of compost will have different requirements for particle size distribution. The most demanding user group in this regard will be horticulturists who use the material in potting mixtures. Those who will use the compost to amend soils (e.g., top soil producers, landscapers, orchardists, field crop growers) will have less stringent requirements, but still should be provided samples of the product to test prior to deciding on an appropriate particle size specification.

Absence of Weed Seeds
It is essential to produce a product that is free of viable weed seeds. This is important for both on-farm use and retail distribution. In general, weed seeds are killed when exposed to temperatures that meet the PFRP conditions. A simple test can be conducted by placing compost in a flat and enclosing it in a clear plastic bag or a green house where it is not exposed to wind blown weed seeds. A weed free product will not produce any seedlings within a 2 to 3 week period.

Concentration of Other Elements
The content of undesirable elements in compost, such as heavy metals, (e.g., cadmium, copper, zinc, lead, mercury, nickel, and chromium) are generally found in very low concentrations in farm wastes, yard debris and hence the final compost product. Nevertheless, laboratory tests should be conducted at the start-up of a composting facility for these elements, as well as pesticides and herbicides. Test results showing an absence of these potential contaminants can be used advantageously in the marketing program.

Product Consistency over Time
Product consistency is one of the most important parameters to end users. In order to incorporate compost into their operating practices, users must be certain that each batch of material has the same properties, within relatively narrow limits. Inconsistency in product quality will result in reduced consumer confidence and may significantly jeopardize future marketing efforts. It s extremely difficult to overcome negative perceptions. If the product is inconsistent because of seasonal variations in feed-stock materials, it may be best to sell separate products in smaller quantities.

For more information on the subject of On-Farm Composting, as well as training workshops offered by Price - Moon Enterprises, contact Peter Moon at 10221 159th Ave. SE, Snohomish, WA 98290, 360/568-0146, e-mail: pricemoon @aol.com.

As every farmer knows, there is ever increasing pressure to reduce the impacts to the environment from what have long been considered traditional methods of farming. In part, this is the result of a more stringent regulatory environment. It also results from more intensive farming methods combined with a decrease in land base. The primary areas of concern include:

* Surface Water Contamination - Runoff
* Ground Water Contamination - Infiltration of nutrients, primarily nitrate
* Odor Management - Urban Encroachment on Rural America
* Organic Waste Disposal - Permissible and Cost Effective Alternatives

Permits for on-farm composting operations are generally not required for small to medium size facilities that utilize the finished compost on the farm (i.e., do not sell the products on a wholesale or retail basis). Nevertheless, a composting facility must be operated in compliance with state and local regulations pertaining to surface water, ground water and odors. Negligence in any or all of these areas will likely result in an order to mitigate the problems, as well as ensure the attention of the jurisdictional health district and the myriad of other regulatory agencies at local, state and federal levels. For these reasons, care must be taken in planning not only the location of on-farm composting system, but the method and timing of operations as well.

A site for an agricultural composting facility must provide the required area and conditions for all-weather composting as well as limit the environmental risk associated with odor, noise, dust, leaching, and surface water runoff. Site planning involves finding an acceptable location, adapting the composting method to the site, providing sufficient land area (allow for future expansion), and implementing surface water runoff and pollution control measures as needed. The materials being composted and system management will also impact these environmental concerns.

The location of the composting site should allow easy access, a minimum of travel and materials handling, and a firm surface to support vehicles under varying weather conditions. Usually, the most convenient composting site on the farm is near the barn or manure storage facility. However, the convenience of a particular site must be weighed against factors such as area (can the facility be expanded), proximity to neighbors (up wind or down), visibility, drainage and runoff control. The best site on the farm may not be the most convenient; or a convenient site may require modifications such as grading or drainage improvements.

It is also important to be aware that starting a composting facility may raise concerns among neighbors and local public officials. Educating these groups about composting and its advantages will be a critical part of getting started smoothly. It is essential to include concerned individuals in the planning process from the beginning to develop a "good-neighbor" working relationship.

The separation distance, or buffer zone, between the farm composting operation and streams, water resources, and nearby human housing is intended to address water quality concerns and the nuisance factors of odor, dust and equipment noise. The On-Farm Hand-book (NRAES-54) recommends the following minimum separation distances.

Sensitive Area	Minimum Distance (feet)
* Property Line	50 - 100
Residences or Places of Business	200 - 500
*Private well or other potable water source	100 - 200
Wetlands or surface water (rivers & lakes)	100 - 200
* Water table (seasonal high)	2 - 5 (vertical)

Good drainage at composting sites is critical. Poor site drainage leads to ponding of water, saturated compost materials, muddy site conditions, and excessive runoff and leachate (impacted water) from the site. In areas of moderate to high precipitation, composting operations should be conducted on an impervious surface, such as concrete or asphalt, or under cover to provide all-weather access to composting equipment and to avoid contamination of the finished compost with soil and rocks. An impervious surface also serves to protect infiltration of compost leachate and prevent contamination of the ground water. The site should be graded to direct surface water runoff to one or more collection points (e.g., catch basins, manure lagoons, retention ponds). The collected runoff can be directed to pasture, cropland, or retained for future beneficial use.

Odor is the most frequent reason for composting facilities to be shut down. Sites near sensitive locations, such as schools, hospitals, and nursing homes, should be avoided. Odors from the com-posting process are minimized through good management only if the composting system is properly designed and laid out. In siting the facility, consider the direction of prevailing winds during warm periods (open windows and outdoor activities) and cold periods (thermal inversions). Turning windrows should be avoided during high impact weather conditions.

Reference: "On-Farm Composting Handbook," Robert Rink - Editor, Northeast Regional Agricultural Engineering Service, Publication No. 54. Inquiries invited. (607) 255-7654.

Author: Peter Moon, P.E. is a consulting engineer and on-farm composter, in rural Snohomish, WA. For more information on the subject of On-Farm Composting, as well as training workshops offered by Peter's company Price - Moon Enterprises, call (800) 611-3718, or e-mail: pricemoon@aol.com