Inside a Sample Compost Extract Operation
By Simeon Kleinsasser
Simeon Kleinsasser is a Soil Food Web-trained consultant located in New York’s Hudson Valley. His soil care projects include mixed vegetable gardens, pastures, residential landscaping, and fourteen acres of high school athletic fields.
Simeon explains how he used Hiwassee Products’ first prototype compost extractor to produce 5,500 gallons of extract in one day.
Space and infrastructure:
I perform my compost extraction in an equipment shed, which also houses my vermicomposting bin and my microbial food storage, all of which needs to be kept at an ambient temperature of 50-80 degrees Fahrenheit, optimally around 70. That’s a good temperature for producing and storing compost extract as well. Since I live in upstate New York, annual temperatures rise above and fall below that range, so my shed is insulated and I have a small electric heating / cooling system. I don’t need a lot of space to run the extractor – I only have about 600 square feet to work in, although I can roll the extractor outdoors for operating in warmer weather.
My shed has single phase electric power, which is all the extractor needs. Water supply is an important consideration when working with microbiology, since a high mineral content – especially over 75 ppm of calcium – can damage micro-organisms. Some people collect and store rainwater, which should still be tested. I run my groundwater supply through a reverse osmosis system and store 1000 gallons of filtered water in two cone-bottomed tanks.
Sourcing and preparing compost:
As a Soil Food Web consultant, I’m able to test compost sources for microbial content and verify the product as biologically complete according to Soil Food Web standards. This allows me to determine the expected microbial levels of the compost extract I produce. I have mostly outsourced commercial vermicompost for my extracts; however, I’m working on producing my own vermicompost, which is a lot more cost-effective, using a prototype continuous-flow-through (CFT) bin from Hiwassee Products. This also allows me to control the composting process and recycle local organic materials, including ramial wood chips, which contribute to more fungal-rich vermicompost.
To prepare the finished compost for extraction, I screen out any larger aggregate materials so that they don’t get stuck in the Bio-Extractor auger or rip the mesh sleeve. I store compost for future extraction in my shed, where the ambient temperature remains around 70 degrees, and where I can control the moisture level. 50 percent moisture is optimal for preventing the compost from either becoming too dry for microbial life, or too wet, which can cause anaerobic conditions.
Operating the Bio-Extractor:
When I’m producing a run of compost extract, I draw water from one of my cone-bottomed tanks and pump the finished extract into the other. The Bio-Extractor has a standard 1” camlock connection for the water source; I made my own custom connection system with 1 ½” hose line from Sprayer Depot and fittings from Pro Flow Dynamics. The extractor pumps control the water pressure flowing through the machine.
Since the Bio-Extractor produces a continuous flow of extract, I can produce any batch volume at a time, depending on my storage capacity or application needs. I determine my input of both water and compost depending on the acreage and rate of extract per acre of each application. If I use up all the compost before completing my target liquid volume, I’ll add water until I have the right amount. The Bio-Extractor auger speed can also be adjusted to increase or decrease the concentration of the extract during production.
Typically, a five-gallon bucket holds 30 pounds of vermicompost, which is a good fill amount for the compost hopper. The auger speed will determine how quickly the compost is extracted, but I usually figure on dumping in a five-gallon bucket about every 15 minutes. It takes about twice that time to fill a five-gallon bucket with the solid material being augured out post-extraction.
Finished extract is pumped out through a 1 ½” hose, which can be connected to a storage or application tank if desired. If I’m producing extract for an immediate application, I’ll pump the extract into a mixing tank, where I’ll add in microbial foods such as kelp and molasses before pumping the enhanced extract into the application system. Since all the liquid is contained between the water source, extractor, and collection system, there is no wasted water and almost no spillage.
During the process, sediment collects at the bottom of the extractor basin, so I usually flush it out every 300 gallons or so. Both the flushed sediment and the leftover solid material will retain some microbial life, so they can be recycled back into the composting system or used for high-quality potting soil. Both outputs can be easily collected in five-gallon buckets placed below the extractor. If I’m running the process in my shed, I usually just dump the buckets into my vermicomposting bin.
Cleanup and sanitizing:
Cleaning the machine after extraction usually takes about 30 minutes. I don’t have a drain in my shed, so I wheel the extractor outside and connect it to a garden hose. The Clean function will perform an initial rinse, followed by a 15-minute cycle, during which time I can disconnect the hose and spray down the exterior of the extractor before reconnecting the hose for the final rinse.
I periodically use the Sanitize function, which uses 10 oz of hydrogen peroxide, when I’m using the extractor heavily, or after my final extraction for the year.
Storing the extract:
The Bio-Extractor produces a non-aerated extract, which holds the microbiology in homeostasis without stimulating activity and growth. If I’m not planning to apply the extract immediately, I store it for up to 3-4 weeks in one or both of my cone-bottomed tanks, at the ambient temperature in my shed and away from any direct sunlight. I circulate the extract in the tank daily by running it through a pump for 5-10 minutes (using the same pump and hoses I use for mixing and conveying extract to the application system). This process introduces enough oxygen into the liquid to maintain aerobic conditions without over-stimulating the microbes, increasing the shelf life.
Applying the extract:
I’ve applied the compost extract I’ve produced with a number of different systems, including a trailer-mounted spray rig I built myself. It draws extract through a diaphragm pump from two IBC totes and has a 30’ boom with 21 Floodjet spray tips spaced every 20”. I spray at a low pressure, around 40 PSI to protect the microbiology during application.
I always add microbial food to the extract before applying it in the field – I think of it as sending the microbes out to work with a lunch pail in hand. I pump the extract into a mixing tank and add in kelp, fish hydrolysate, molasses, humic acid, and fulvic acid, which I then circulate within the tank for a few minutes before filling up my sprayer tanks.
My application methods vary depending on the soil conditions and time of year. I like to apply a heavy dose of static extract with plenty of microbial food in the spring and fall, so that the microbes are able to establish themselves in the soil before and after the growing season. During the growing season, I’ll apply a few rounds of a foliar spray, which I usually aerate the day before application to stimulate the microbes. Communities of beneficial microbes on leaf surfaces are an excellent defense against pests and pathogens. If the plants I’m treating are showing signs of micronutrient deficiencies, I’ll add in those micronutrients for the plants’ leaves to absorb.