In collaboration with the St. Louis County Public Health Department and the City of Ferguson, EarthDance is working to streamline the process of composting in an urban setting. Through a Waste Reduction Grant offered by STL County, “The city [Ferguson] will use grant funds to subsidize the costs of commercial single stream recycling for 13 businesses in a business district. Besides diverting waste from landfills, patrons of those participating businesses will learn about recycling while on the go” (Recycling News).
The Farm’s main inputs for composting are:
- Alpaca Manure via Michelle Zumwalt
- Brewery Grain from the Ferguson Brewery
- Coffee Grounds from the Corner Coffee House
- Yard Waste (from EarthDance)
- Leaf Litter
With the assistance of a representative of Lincoln University the first two thermal compost windrow piles were constructed in the Spring of 2015. A third pile was constructed in early June of that year in conjunction with a “Composting Field Walk” offerred to the Apprentices, who then assisted with the construction of the pile. As an intern through the Americorps VISTA Summer Associate Program, I facilitated the record-keeping and maintenance of the piles and assisted the Farm Managers in meeting future goals. A compost stable was constructed in August of 2015 to contain input materials and provide support for the tractor.
As a Certified Organic Farm, EarthDance must ensure that its compost meets existing regulations and keep accurate records. Due to the intensive nature of thermal composting, EarthDance must rely on a combination of cold/thermal windrow composting and vermicomposting to meet the standards outlined by the National Organic Program. EarthDance will construct windrow compost piles to mix and initiate decomposition of the inputs, and then move these piles to the vermicompost system. The bulk of compost production should happen in the spring and summer, with curing occurring in the late fall and throughout the winter. The compost should then be ready to apply to the fields for the next season.
According to the Kerr Center for Sustainable Agriculture at the University of Oklahoma:
Compost is decomposed organic matter, managed to: grow beneficial microbes, concentrate nutrients, and build humus. The benefits of compost as a soil amendment include improved soil structure, increased water holding capacity, improved soil aeration, slow-release fertility, and stimulation of plant growth.
In thermal, windrow composting, microorganisms consume oxygen as they break down the organic materials present. Temperature will increase and indicate microbial activity. This signifies that the organisms are eating easily degradable compounds, like sugars! This is noticeable within a few hours of creating the compost pile. Usually the temperatures increase rapidly to 120 -140 degrees Fahrenheit, and this is maintained for several weeks. Over time, the temperature gradually drops to 100 F and then to ambient air temperature (matching the temperature of whatever environment the pile is in). During the composting process carbon dioxide and water vapor are released into the air. Sometimes methane is released if conditions in the pile lack oxygen and become anaerobic, although this is not desired for compost or environmental quality.
In vermicompost systems, red wiggler worms convert organic waste into worm castings (worm poop) which are rich in plant nutrients. After eating through the organic material they move to new parts of the compost area that have not yet been digested, leaving behind a dark, fertile compost that we can use (more on vermicompost below).
Aside from thermal and vermicomposting, there are many ways to compost. Passive composting, windrow, passively aerated windrow, aerated static pile, rectangular agitated bed, rotating drums, hugelkultur, and vertical silos are only some of the different composting methods available. Different ancient cultures had other ways of disposing of organic wastes and composting, such as composting pits!
Many factors affect the composting process. Composting is like a coordinated dance, and every set of partners (or recipe of organic waste inputs) are all connected and will yield different results. The main things to consider are:
- Carbon to Nitrogen Ratio (more details below)
- Porosity, amount of open space in compost pile
- Particle size
And how does a prospective compost Master know what to compost? Sticking to organic materials, these items are suitable for compost:
- Kitchen wastes including fruits, vegetable peels, tea bags, coffee grounds and filters, eggshells, and more
- Manure – especially in truly thermal composting operations. The hot temperatures will kill manure pathogens. Manure is an excellent source of nitrogen and nutrients to be added to the compost.
- Grass clippings, yard waste, leaves
- Hay, straw
- Woodchips, sawdust – smaller sizes are beneficial for quicker composting
- Meats, bones, and fats are commonly discouraged from incorporation into compost piles. However, with hot thermal temperatures (greater than 130 F for 15 days), these materials should decompose quickly and easily and pathogens will be destroyed. The surface area of these items will also affect their rate of decomposition – the smaller they are the faster they will break down as the heat reaches more of their surface. Opt out of these materials if your composting is more passive and less heat intensive.
- Discouraged: weeds, chemically treated woods or other chemically treated organic materials, diseased plants
A less intensive form of composting than thermal composting, vermicomposting utilizes the hungry stomachs of red wiggler worms to decompose organic material. For vermicomposting the main thing to remember when preparing your compost is to maintain proper moisture and temperature levels for worm survival. The worms thrive in environments of 60-90% moisture content. Temperatures of over 100 F can kill the worms, and temperatures below 50 F will slow down their activity.
There are several ways to establish a vermicompost system. Red wrigglers are known as surface dwellers – they naturally live in leaf litter on the forest floor. These organisms thrive at the surface of the compost, eating what is placed there. They produce worm castings, or “small soil beads,” that form clumps or aggregates (Vermicomposting at Kerr Center). Vermicomposting varies throughout the year.
Warmer Months (Late Spring – Late Summer)
- During warmer months, vermicompost will be successful outdoors. To begin the process, create a layer about 6 inches deep of mixed and partially decomposed material (leaf litter, other compost, manure, etc – in EarthDance’s system, the starting material for the vermicompost system will be the thermal compost). Ensure that the layer is at about 60-90% moisture content. Add red wiggler worms to the layer. Cover the top with a small layer of leaf litter.
- As the worms work their way through this layer, add another layer on top and again cap it with leaf litter. Continue to work this way over time, ensuring proper moisture conditions are maintained. When the compost is ready (a rich, dark compost full of small clumps and a good smell), encourage the worms to move out of the finished pile. This can be done in several ways.
- Add a new pile of food to one side of the finished pile. The worms should gradually move over to the fresher food and leave behind the finished compost.
- Worms shy away from sunlight and heat. If you shine a light on one side of the pile they will move away from it.
- Additionally you can move the pile into direct sunlight. The worms will start to move towards the center of the pile. Slowly scrape away the outer layers of the finished vermicompost, returning every 30 minutes or so (allowing time for the worms to move inwards). At the end of this adventure, you should have harvested the finished compost and have a writhing mass of worms that you can reincorporate into a new vermicompost system.
Colder Months (Late Fall – Early Spring)
- In a temperate location like Missouri, the worms will have to be moved inside. This can be into a greenhouse, basement, or even your home (good compost shouldn’t smell). This also means that production may have to decrease in volume for the colder months, due to a lack of available space.
- A great indoor system utilizes milk creates stacked vertically. Fresh input materials and the worms are placed in the bottom crate. Once the worms have decomposed the food in this crate, a second crate is placed on top with more food. The worms move up into this new crate, leaving behind a fresh, finished compost in the bottom crate. The pattern continues as such, allowing the fresh compost to be harvested from the bottom crates, and new food to be added to crates above.
Additional Notes (adapted from the Kerr Center for Sustainable Agriculture):
- Add cardboard, newspaper, or other carbon-rich materials on top to preserve the moisture and to darken the environment for the worms.
- Aluminum fly screens can be used to prevent fly problems.
- Black soldier fly larva proliferate in really moist, anaerobic worm bins. Ensure the bin/pile has good air flow.
- Worm population growth: Doubles in 60-90 days.
- Use lime, azimite, or rock dust to provide grit and micronutrients for the worms (Vermicomposting at Kerr Center).
Tea is an extract of a substance in water. The resulting liquid then possesses beneficial properties of the substance, in a diluted and easily dispersible form. Compost tea promotes the growth of beneficial microorganisms, originally present in the compost, and allows these organisms to be transferred to leaf and soil surfaces. At EarthDance, they have a 5-gallon Compost Tea Brewing Kit with an extended life motor from Keep It Simple, Inc.. According to the company’s website, the product:
…Was developed to provide an organic solution for caring for our plants and soil, to help eliminate the reliance on harmful pesticides, and minimize the use of chemical fertilizers. It works by inoculating the plants and soil with the necessary microbes, that are often lacking in an urban setting, that the plant needs to ward off diseases and be healthier.
Dr. Elaine Ingham, a renowned soil scientist with regards regenerative soil practices, recommends use of the kit. It is straightforward and easy to use, and comes with starter materials (compost and microbe inoculant) that allow for easy tea production (Keep It Simple).
Carbon to Nitrogen (C:N)
- Carbon, nitrogen, phosphorous, and potassium are the four critical nutrients to soil and plant health.
- Carbon is used for microorganism growth and energy.
- Nitrogen is needed for protein and reproduction of microorganisms.
- It is important to have a proper C:N ratio to ensure that the carbon is fully utilized while the nitrogen is stabilized. Otherwise the nitrogen can be lost to the atmosphere as ammonia or nitrous oxide (which leads to smelly compost, yuck).
- A note about particle size and composting rates: Some materials have more readily available carbon or nitrogen. This is another factor to consider in constructing a pile. For instance, straw decomposes more easily than woodchips, and fruit wastes decompose faster than straw! This just means that for items requiring more time to decompose, the composting process will be slow. If you want to speed up the rate of composting, reduce the size of the particles added to the pile.
- Ideal starting C:N ratio for compost mixture: 30:1
- Reasonable range: 25:1 – 30:1
- As carbon gets converted to CO2 (and assuming minimal nitrogen losses) the C:N ratio decreases during the composting process, with the ratio of finished compost typically close to 10:1. (Richard, 1992).
- The On-Farm Composting Handbook has a very essential method of calculating the total C:N ratio of your mixed pile. Remember that this calculated ratio will be “ideal” since your compost’s inputs will differ in moisture content, age, and otherwise from the inputs given by other references. But it should provide you with an idea of how your compost fits into this desired C:N ratio range, and therefore perhaps explain its performance.
Atchley, Kate. Hot Composting with the Berkeley Method, 2003. The Kerr Center for Sustainable Agriculture. Web Document. Obtained From: http://kerrcenter.com/wpcontent/uploads/2014/06/hot_composting.pdf
Darwish, Liela, 2013. How to Make Aerated Compost Tea, Mother Earth News. Web. Obtained from: http://www.motherearthnews.com/organic-gardening/gardening-techniques/aerated-composttea-zebz1307zsie.aspx?PageId=2
Frequently Asked Questions. Keep It Simple, Incorporated. Web. Obtained from: http://www.simplici-tea.com/simplici-tea-wp/home/frequently-asked-questions/
Keep It Simple Organics. Web. Obtained from: http://www.kisorganics.com/products/shop/keep-itsimple-5-gallon-compost-tea-brewing-system
Ingham, Elaine. Compost Tea Recipe, Soil Food Web. Web. Obtained from: http://www.soilfoodweb.com/
Recycling News, St. Louis County Public Health Department. Web. June 28, 2014. Obtained from: http://www.stlouisco.com/HealthandWellness/RecyclingandSolidWaste/RecyclingInformation/RecyclingPublications/RecyclingNews#article2
Richard, Tim. On-Farm Composting Handbook, 1992. Cornell Waste Management Institute. Web Document and Book. Web source obtained from: http://compost.css.cornell.edu/OnFarmHandbook/apa.taba1.html
Seedfelt, S., & Smeenk J., 2015. Using Spent Grain in the Alaska Compost Pile, University of Alaska Cooperative Extension Service. Web. Obtained from: http://www.uaf.edu/files/ces/publications-db/catalog/anr/HGA-01026.pdf
Vermicomposting at Kerr Center I and II, 2013. Kerr Center for Sustainable Agriculture. Web. Obtained from: http://kerrcenter.com/video/vermicomposting-kerr-center/
Much of the information in this document is published on the web and all interpreted for specific composting efforts at EarthDance Organic Farm School. Dr. Elaine Ingham, Josef Biechler from Finca Luna Nueva in Costa Rica, and the On-Farm Composting Handbook are essential to this document and were the major sources.