Zack McClellan
Senior Seminar
Dr. Derek Stanovsky
Interdisciplinary Studies Department
Appalachain State University
April 2007
Vermicomposting and Cold Climate Vermicomposting
I. Abstract
II. What Is Vermicomposting and How Does it Differ from Traditional Composting?
A. Introduction to Composting
B. Composting Techniques
C. Vermicomposting
III. The Process of Vermicomposting:
A. Buy or Build
B. Scale and Size
C. Materials
D. Construction
E. Location
F. Bedding
G. Choosing the Correct Worms
H. Feeding
I. Harvesting
J. Using the Castings
IV. What is a Coldframe?
V. Cold Climate Vermicomposting at the Goodnight Family Sustainable Development Farm (Valle Crucis, NC)
A. Introduction
B. Site Selection
C. Coldframe Design
D. Coldframe Construction
E. Data Collection
F. Future Improvements
G. Alternative Uses
VI. Conclusion
VII. Bibliography
Abstract
I. My senior project will be researching and developing an experimental cold climate vermicomposting system. The project will provide extensive and in-depth research on vermicomposting and its benefits, specifically to local farmers, gardeners, and the ASU farm, over general composting techniques. The second part of my project will be the construction of a vermicomposting system specifically designed for cold climate functionality. The vermicomposting bin will double as a hotbed for active composting or as a coldframe for growing tropical plant varieties during the warm season or starting seeds early in the growing season. As stated on Appalachian State University’s SD web site the goal of the Sustainable Development and Research Farm in Valle Crucis is to educate, “students in agroecology, agroforestry, and sustainable, organic and alterative farming practices. Experimentation and information facilitates exchange with the local community in an effort to help local farmers and entrepreneurs better build and foster alternative, sustainable agricultural practices in the region” (www.susdev.appstate.edu). It is with these goals in mind that I will be further developing these alternative and organic gardening/farming practices. The general intention of this project is to enhance local organic food production capacity through the facilitation and exchange of innovative, locally specific farming techniques. Reducing local reliance upon foreign external inputs, i.e. commercial petrol-based fertilizers, is an integral factor in increasing our regions capacity to consistently produce organic foods in the current and future markets of increasingly expensive petroleum based products. It is my objective through the research and development of this project to provide local farmers and entrepreneurs with progressive locally specific information to aid in this regions organic agricultural production capacity.
II. What Is Vermicomposting and How Does it Differ from Traditional Composting?
A) Composting is defined as the controlled decomposition of organic matter (wikkipedia.org). Composting can be accomplished through a number of techniques. Each technique has certain advantages and disadvantages over their alternative, but regardless of the technique the end product provides farmers and gardeners with a product of multiple functions. Most commonly compost is simply worked into the top six inches of the soil or mixed into the soil mixture. Many soil recipes call for compost as a major ingredient due to its beneficial soil structure characteristics and high concentrations of macro and micronutrients along with beneficial bacteria and other soil organisms. All of the contents of properly decomposed compost are beneficial to most any plant, tree, shrub, or vegetable of earth. It is for this reason that composting has ancient roots in agricultural practices. Civilizations as far back as the Acadian Empire (2340BC) in the Mesopotamian Valley recognized the benefits of composting. Virtually every civilization has at least some traditional form of composting used specifically to increase agricultural outputs. It should therefore be a concern of every modern farmer and gardener to educate themselves of the benefits of composting as well. Before the Green Revolution of the 1940’s composting played a vital role in the maintenance of farmers and gardeners soils across the nation and world. The effects of the rapid transition to petroleum based fertilizers to what is now referred to as conventional agricultural practices on farmers and the environment is now becoming increasingly apparent. These conventional agricultural practices expose not only the farmer, but the consumers of their products as well to a multitude of harmful chemicals. The exposure to these chemical concoctions reduces the health of the American population along with our ecosystems capacity to filter our air, water, and soil. Conventional agricultural practices are also partly to blame for increased rural poverty and further concentrations of wealth. The pollution of watersheds threatens biodiversity and the natural balance of ecosystems worldwide. The reliance on large companies to provide inorganic fertilizers has increased farmer debt worldwide by trapping them in a never ending cycle of forced purchases. This is especially true in less affluent nations across the globe. Entering into contracts with multinational corporations such as Monsanto who’s genetically modified products require many farmers to not only buy seeds but, herbicides, pesticides, and fungicides in order to produce a yield large enough to provide them with their means of subsistence places farmers at an increased risk of debt. The switch back to organic food production is becoming a more economically viable decision with every passing day. With an increasing worldwide demand for petroleum and a decreasing supply the price of petrol-based fertilizers will continue to rise placing increasing social and economic pressure on farmers well into the future. It is for these reasons that organic composting should once again be the farmers and gardeners major source of fertilizer and soil additives.
B) There are several major composting techniques in use today by gardeners and farmers. The first and most common is heap or passive composting. Heap or passive composting requires the least amount of energy and time and basically consists of two steps. First collect organic waste and pile it up. Then let it sit, usually for at least one year, turning monthly until the organic waste resembles dirt then screen and harvest. This technique is passive in nature and therefore produces the least potent compost. While it may be the least potent it is still beneficial and worth the effort. The saying, “you get out what you put in?” is a general rule for composting. The second technique called active composting is less common, probably due to the increase in time and effort, but produces compost with a higher nutrient content. This process is also quite simple and begins in the same way with the collection of organic matter. This technique differs in the frequency of the turning of the piles which should be done at least every ten days. Generally those who compost in this manner have a series of compost piles all in different stages or what is known as a tumbler. This technique increases the potential yield by decreasing the decomposition period from approximately one year to as little as thirty days. This composting process also produces an end product with increased levels of nutrients over passive composting. A third composting technique is trench or pit composting. This method is most commonly used to build soil structure in new beds or to fertilize trees. The process has three stages. First dig a three foot wide hole or trench if establishing a new bed, approximately one foot deep. Fill the hole/trench with stockpiled organic material and cover. Repeat process a second and third time. The organic material will decompose in as little as one month, but may take as long as one year depending on quality of soil around the material. When decomposed the compost will naturally fertilize the tree or if in a bed the ground should be tilled to mix the soil and compost before planting thereby increasing soil structure and available nutrients. The end result is a slow release fertilizer for trees or in the case of beds a mixed soil rich in nutrients, soil organisms, and structure. Another composting technique is known as hot composting. This process is much like active composting except the compost pile is in a coldframe. The coldframe increases the rate of decomposition by increasing the temperature at which the decomposing organic matter is subjected to. It is this increase in temperature that increases the rate of decomposition and sterilization. Sterilization is especially important when composting organic matter with seeds such as apples or weeds. The increased temperature provided by the coldframes insulation and passive solar properties further increases the consistency of sterilization. These are just a few of the most common composting techniques. All of which produce vital organic compounds for increasing soil health, structure, and nutrients, but none of these techniques have the capacity to produce compost as rich and beneficial as vermicomposting.
C) Vermicomposting is the end product of the break-down of organic matter by some species of earthworm (wikkipeia.org). The end product, known as castings, contains from 5 to 11 times more nitrogen 7 times more phosphorus and 11 times more potassium than other composting techniques and can be used in multiple forms (http://cahe.nmsu.edu/pubs/_h/h-164.pdf). For example the castings can be used as a direct fertilizer and soil structure builder, as an additive for soil recipes, a stress reducer for plants, and to make worm tea. There is also a natural liquid by-product of the vermicomposting process which can be diluted with water to a 25-50% solution and used as a fertilizing foliar spray. Mixing castings into chicken feed will also boost the birds’ immune system decreasing the chances illnesses. These benefits over other composting techniques makes apparent the potential vermicomposting offers gardeners and farmers alike. While the end product holds the most nutrient capacity and the most useful form of compost it is not the most time and labor intensive of the composting techniques once a system has been established. It is actually quite the contrary. Once a worm bin has been built bedded and filled with worms and organic matter the labor falls on the worms. There is no need for constant monitoring, turning, or rotating of piles only harvesting. The harvesting process is as simple as you want it to be. A composter can simply scoop out the casting as needed or use a screen to sift through and separate the finished from the incomplete compost, returning the incomplete back to the bin. The process is quite efficient, but does generally take a little longer than active or hot composting, but with much less effort and a better more useful end product. This is just a general overview of the process of vermicomposting meant to introduce and familiarize you the basic principles. Each stage of the process from the construction of the bin to the harvesting of the castings will be discussed in greater detail later.
III. The Process of Vermicomposting
A) The VC process is simple and begins with the worm bin. The first decision is should you build or buy you worm bin. There are several major companies now producing vermicomposting bins and complete systems for sale. The bins and systems themselves vary in construction material, size, capacity, and design and range from 50-$450. There are indoor and outdoor models available some designed to fit under the sink and compost for two and others are independent structures designed to fit in your kitchen and double as a chopping table with the capacity to compost for a family of seven. Vermicomposting is becoming so popular that some manufacturers are building vermicomposting systems that are as stylish as they are functional. While there is no need to be stylish some are willing to pay extra for the convenience of a system that looks good enough to be a permanent fixture in their kitchens thereby reducing the need to transport scraps from the kitchen to wherever there bin is. If you are less apt or willing to spend money on something you can build yourself then the first factor to take into consideration is the necessary capacity of you system.
B) Red worms, the most common vermicomposting worm, can consume 50-75% of their body weight per day. So the first thing you need to do is determine the average amount of daily waste produced by your household. A general rule for determining the necessary size of your bin is to allow one square foot of surface area per pound of waste.
C) Next determine the material you wish to construct your bin out of, wood or plastic. Plastic bins come pre-shaped and sized and will outlast any wood bin and are generally cleaner and easier to maintain, but provide less insulation and moisture wicking capacity. Wood bins have a shorter life span and require construction, but are great at wicking excess moisture and providing insulation from vibration and cold temperatures. There are a wide range of plans for different sizes, and designs available online. Reviewing some of these different system designs is advisable to help insure you choose the best capacity and design for your needs. There are big differences in the design of small and large scale vermicomposting systems therefore researching design is critical in insuring a proper composting environment and desired output.
D) Once the proper material, size, and design have been chosen the next step is to construct the bin. Be sure to drill holes in the top and bottom of bin for proper drainage and ventilation. The bin should also be elevated to allow for excess liquids to drain out. Don’t just let this liquid fall to the ground place a collection tub underneath the bin to retain this liquid which is known as compost tea and may be diluted with water and used as a foliar fertilizer spray. The bin should also be covered or sheltered from light. Worms don’t like light so they will burrow down to avoid leaving the organic waste on the top of the pile un-composted. A cover is also helpful in deterring unwanted pest especially in outdoor bins. In some climates it may also be necessary to insulate your outdoor bin from the cold. There are a couple of ways of doing this. You can in locations with mild winters pile dirt around the bin providing a windbreak and insulation. In even colder climates it may be necessary to place your bin in a coldframe. The use of coldframes for cold climate vermicomposting will be discussed in greater detail later.
E) Once you have built your bin the next step is to find a suitable location. Most anywhere is fine just make sure to avoid loud noises of constant vibrations. Worms are very sensitive to vibrations as well as light and will try and leave if the are unhappy. Avoid placing bins near washing machines, dryers, speakers. and other sources of vibrations to keep your worms happy and in their bin.
F) The next step is to find and place some bedding in your bin. Bedding is used as a medium between the bin and the organic matter which helps to simulate their natural habitat, established forest floors. The bedding provides moisture retention an alternative food source as well as a non-dense cushion increasing airflow thereby increasing the rate of decomposition and reducing odors. Suitable bedding materials include: new, notebook or computer paper, cardboard, hay, sawdust from untreated wood, pre-composted manures with the exception of humanure, coffee filters, coconut fibers, pre-soaked peat moss, dead leaves, and commercial worm bedding. Any one or combinations of these materials are suitable for bedding. All bedding must be shredded and moistened, but not soaked before being placed into bin. Place your choice of bedding into the bottom of the bin along with a handful of dirt or coffee grounds into a six inch layer. Remember to leave some bedding to cover the surface of the bin as well after the worms have been fed. The dirt or coffee grounds benefit the vermicomposting process in two ways. First the dirt or coffee grounds introduce bacterian essential for the reduction of odors and the natural decomposition of the organic matter. And secondly the dirt or coffee grounds act as course material which aids in the worms digestive process. The next step is to select the type and quantity of worms.
G) There are two common species of worms used for vermicomposting and they are Red Wigglers (Lumbricus rubellus) and Brandling worms (Eisenia foetida). Both types are well suited for soils high in organic matter and are the most comfortable and productive in composting environments. The common earthworm however is not suited for composting environments and will flee or die in vermicomposting habitats. Both Red Wigglers and Brandling worms are available online and at some organic agricultural supply stores and generally cost between $20 and $25 per pound. If your bin is large you don’t have to buy a lot of worms if you don’t want to. Both species of worms are hermaphroditic and will reproduce every 15-21 days eventually populating their environment until the maximum threshold of their habitat is met. From then on the worms will self regulate their population.
H) Next you are ready to feed your worms. Feeding should begin as soon as your prepared bedding has been placed in the bin, but be sure to add food gradually over time. Bacteria needs to build up to reduce odors and before maximum output can be achieved. A great jump start source of these bacteria is found in coffee grounds as mentioned previously. Worms are not picky eaters and will consume most anything. Avoid meats and fat, greasy or oily foods, raw manures, garlic and onion skins, and an excess of citrus rinds which can raise acidity to much and are slow to be consumed because of their acidity. It will generally take between two and four months before harvesting is necessary.
I) The next and final step in the vermicomposting process is the harvesting of the castings. Harvesting the castings is a very simple process, though there are more complex and time consuming methods I have found no evidence that these other techniques are any more efficient or easy so I will provide the most basic of methods. The simplest technique is to construct a wooden frame no less than 1square foot in size and cover it with screen of no greater mesh size than ¼ inch. Next place the sifter over a wheelbarrow and add scoops from the compost bin one at a time gently working the material across the screen. The finished compost will fall through while the unfinished remains on top to be returned to the bin. The castings should then be stored in a dry place like Ziploc bags of plastic containers.
J) Now that you have harvested the worm castings it is time to use or sell them. Worm castings are becoming an increasingly popular soil conditioner with the growing organic foor production market and are generally worth about $3 per pound. If you are vermicopmposting tsupply yourself then now is the time to decide how you will use the castings. Worm castings can be used to make worm tea by steeping in water for several hours to a couple of days. The tea should be used to water plants or as a foliar spray to fertilize. The castings may also be used to side dress individual plants by placing a small mound at the base of each plant. Vermicompost is very mild so you do not have to worry about burning your plants. In potted plants the castings may be added during soil mixing prior to planting to increase soil structure, used to side dress, or spread in an even layer across the soil surface to fertilize. In garden beds the castings may be worked into the soil prior to planting or spread in an even layer across the soil surface with the same benefits as mentioned previously. To boost immunity in seedlings add castings to the bottom of seeding flat before seeding dirt is added. Castings may also be added to chicken feed to boost the immunity systems of the birds. The natural by-product of the vermicomposting process, known as compost tea that collected in the bottom of your bin is also a valuable fertilizer and should be diluted to a 25%-50 % solution and used to water or as a foliar spray.
IV. What is a Coldframe?
Coldframes are transparent-roofed enclosures, built low or into the ground, generally used to protect plants from cold weather. While coldframes have traditionally been used for this purpose they may also be used for hot composting. There are a wide variety of sizes and designs that lend themselves to specific conditions and applications. Commonly a coldframe consists of a wooden frame built even with or slightly below ground level and covered with a window to increase the temperature inside the structure. While most coldframes rely on passive solar energy to increase temperatures some are equipped with heating coils to provide a more consistent increased temperature. Most coldframes with heating coils are used in locations with long hard winter seasons and rely on either a solar panel or the power grid for their power source. Running heating coils off of the power grid will provide the most reliable results it is limited to geographically to locations on the grid and not only cost the operator money, but increase their carbon consumption as well. The solar powered heating coil offers a green alternative to heating, but is expensive and not as reliable as running off of the power grid. An experimental alternative to these heating methods is the combination of passive solar and geothermal heat along with the utilization of the natural insulating properties of the ground. This is method used in my project. A combination of these heat sources along with proper design and building materials provides a cheaper carbon free alternative to heating a coldframe.
V. Cold Climate Vermicomposting at the Goodnight Family Sustainable Development Farm (Valley Crucis, NC)
A) There are two types of vermicomposting systems, indoor and outdoor. Indoor systems efficiently produce vermicompost year-round, but are generally limited in size and scale because they are in the home. Outdoor systems can provide year-round vermicompost in many areas, but in the mountains of North Carolina winter temperatures consistently fall below the minimum working temperature of 37 degrees Fahrenheit. The fatal temperature for composting worms is a topic of much discussion and debate in the world of vermicomposting. Some claim the worms will die in frozen ground while others claim their productivity may come to a halt, but they don’t die. It was these conflicting claims that led me to investigate the possibility with proper site selection, coldframe design and construction of a year-round vermicomposting system in the mountain region of North Carolina. Through my research and online forum conversations with seasoned vermicomposters from across the nation I found a growing interest in the feasibility of year-round outdoor vermicomposting in cold climates. Many of the people I talked with stated they move their systems indoors, run heating coils, or place their coldframes next to their house and heat with the homes warm air. Many call it quits when the cold season arrives believing it is impractical to pay for the vermicompost and simply stockpile waste until the spring. While all of these methods work, except quitting, we at the farm, like many local farmers and gardeners don’t have the luxury of a heated building and solar panels and heating coils are just to expensive for most people including us. So I designed a coldframe that is very well insulated and utilizes passive solar and geothermal heating. The following is a detailed list and explanation of the design principles and materials used in the construction of this experimental coldframe.
B) Site Selection and Preparation: I began by evaluating possible sites at the Goodnight Family Sustainable Development Farm in Valle Crucis, NC to locate my coldframe and vermicomposting bin. After reviewing conservation easement regulations, the topography of the land, and talking to Tamara McNaughton, the student teacher at the farm this semester, a site was chosen. The site was previously an area for storage of humanure barrels, seeding flats, tomato cages, and a new compost pile. First the area was cleared of the materials listed above then the grading and digging began. Using the REI’s Catapillar skid loader the area was cleared and leveled. Next a small berm was made along the outer edge of the site facing the creek to provide protection from flooding. Then using a combination of the skid loader and human labor a 6’ x 4’ x 30” hole was dug out and leveled. Next a 6’ x 4’ x 6” frame was constructed and filled with gravel then covered with chicken wire and then landscaping cloth, both of which were attached to the frame. Next sand was added followed by eight 12” x 12” concrete stepping stones then leveled. This base structure was constructed in order to keep out unwanted scavengers and provide adequate drainage to deter standing water inside or under the coldframe. Drainage was a concern due to the high water table at the site, but through the increased elevation gained through the clearing of the site, proper grading sloping away from the structure, and the porous structure placed under the coldframe no drainage problems are anticipated. If drainage does become an issue the flexibility of the coldframes’ design will allow for the installation of a French drainage system in necessary.
C) Coldframe Design: The design of the coldframe is intended for maximum heat collection and retention. To achieve these goals several techniques were applied. First was the orientation of the structure. Facing the coldframe directly south allows for maximum passive solar heat gain. The next design technique utilizes geothermal heat. Building the structure approximately 30” taller allows for the structure to be buried in over two feet of earth. Using not only the grounds natural insulation properties, but its heat as well further increases the potential to raise and maintain acceptable internal temperatures. At a depth of four feet the earth stays at a relatively consistent temperature between 50 and 55 degrees Fahrenheit year-round. Because of the high water table 30” inches was determined to be the maximum safe depth for the structure. Although the ground at 30”inches in depth will likely not remain within the constant temperature range of 50 to 55degrees Fahrenheit the hope is that at least some of the geothermal heat will be collected and retained within the structure. The final design technique was the use of heavily insulated windows and building materials to retain the heat collected from the ground and sun.
D) Coldframe Construction: The wood chosen for the meat of the structure was untreated cypress because of its natural moisture wicking capacity and rot resistance. The walls were constructed out of 1” x 6’ x 8’ cypress boards and the frame out of treated 4” x 4”’s. This was the only treated lumber used in the construction of the coldframe. The windows selected for the coldframe were double-paned double-glazed with moderate-solar-gain Low-E glass with argon gas fill. The ratings for the windows are a U-factor of 0.38, solar heat gain coefficient 0.31, visible transmittance 0.52, and condensation resistance of 52 and are Energy Star Qualified for North Carolina. These are high tech windows with the latest technology incorporated into their design and construction and are generally over $100 a piece. Fortunately the Restore had the two I needed for a very reasonable price of $20 each. The chosen type of insulation was Blueboard. The inside of the coldframe was first lined with ½”inch Blueboard, rated R-3 and then lined again with 1 ¼”inch Blueboard, rated R-4. Next Great Stuff, canned expanding foam insulation, was used to fill any gaps between boards, windows, and insulation boards. Next vinyl weather stripping was used to further seal between windows and where they lie on the frame. Next a protective wood strip was placed on one of the windows to overlap the two when they are closed blocking out rain and increasing insulation to prevent heat loss. And finally handles and window braces were added to aid in the opening and closing of the structure while reducing stress on the window panes.
E) Data Collection: The data collected from this experiment will come in the form of daily temperature readings from a dual probe digital thermometer. Collected will be the daily minimum and maximum temperature both inside and out. This data collection will run from now through the fall of 2007. From this data a general trend should arise providing and average temperature difference between inside and out. This mean temperature difference should provide the necessary data to infer if the current design will be adequate in maintaining acceptable internal temperatures for the vermicomposting worms or if more work still needs to be done.
F) Future Improvements: The design of this coldframe intentionally lends itself to modification. There is room to tweak and modify almost every aspect of the coldframes’ design. Future improvements could include a French drainage system if standing water becomes a problem. The design of the interior of the structure will allow for up to 3 more inches of insulation along with solid internal walls. Also the size of the coldframe will allow if necessary the inclusion of hot compost inside the structure to increase temperature during winter if the passive solar and geothermal heat are not enough. Hot compost may also be added in times of extreme cold. The dimensions of the coldframe will also allow a wide variety of window types and sizes if replacement or upgrading becomes necessary.
G) Alternative Uses: The design of the coldframe also provides the option for alternative uses. If necessary the coldframe could be used in the traditional way for starting seeds early, growing through the winter, or growing small tropical varieties during the spring and summer. If the structures is used to grow plants a drop-in table will be inserted to raise the plants towards the top to increase the plants light exposure. The coldframe may also be used as a hot bed for hot composting with the simple addition of internal walls.
VI. Conclusion
The intention of this project is to increase regional agricultural production capacity through awareness, understanding, and practice of locally available alternative farming practices. This project and accompanying paper are intended to increase this regions’ agricultural output by making available an organic fertilizer and soil conditioner produced on-site and for free. Making local farmers aware of the beneficial practices and the potential they and their land has to provide them the necessary organic fertilizers needed in organic agricultural production is of the utmost importance in fostering and facilitating this growing source of potential subsistence. It is critical that producers of food be kept up to date with experimental and current alternatives to purchased fertilizers to reduce dependence on external fertilizing inputs and increase profit margins and output capacity. Reducing local farmers’ reliance on foreign external inputs, i.e. commercial petrol-based fertilizers, is increasingly important to maintaining and increasing this regions’ ability to provide for its self. It is my objective to aid local farmers and entrepreneurs by providing this locally specific example of the benefits and viability of vermicomposting to this region’s agricultural industries.
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