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From Arboretum Kitchens to Garden Compost

The Arboretum serves as a host site for a collaborative compost demonstration project with Carver County Environmental Services and Specialized Environmental Technologies, Inc. All Arboretum brush, wood, weeds, dead plants end up at the compost site, as well as food and cafeteria waste from the Arboretum Restaurant.

University Dining Services (UDS) operates the Arboretum Restaurant and supplies it with biodegradable products and packaging materials that are corn resin-based and take approximately 45 days to break down in compost piles. Visitors sort their waste into compost, recycling and trash bins. In May 2012, the Green Restaurant Association designated the Arboretum Restaurant as a Certified Green Restaurant®. Read more at dinegreen.com.

Once collected, waste is brought to the compost site via truck, dropped in the designated area, spread out and sorted into three piles: yard waste, organics and contaminants, such as plastic bags. The Arboretum uses compostable bags to avoid incorporating plastic that can degrade the quality of the compost.

After sorting, brush and stumps are ground into mulch and may be sold or used in the composting process. Organics are mixed together, and the pile is adjusted to reach an optimal level of moisture, carbon-to-nitrogen ratio, and free air space. Read more on the requirements for efficient decomposition. The squeeze test helps gauge how much water is present.

Since piles at the demonstration site can be as high as 12 feet, piping is installed beneath each pile and attached to blowers set on timers that aerate, or push air through, the material, which provides microorganisms with the oxygen required for decomposing the waste.

Blended materials are monitored daily for temperature. Temperatures of 131°F are maintained for 7 days to kill off weed seeds, plant diseases and bacteria. Covering piles with a compost blanket or woodchips helps retain heat. Large machines called windrow turners drive through the pile, turning the material to ensure that colder edge areas move toward the center and to inject more oxygen.

Once the temperature requirement has been met, materials are screened to remove contaminants and then remain in a pile for another 60 to 90 days, being turned occasionally. With its fresh, earthy smell, the Arboretum gardens, and other operations, use the finished compost.

Options where you live

From the most basic (a simple pile) to a homemade cage or bin to a manufactured unit, choices for composting at home abound.

Backyard Composting
Take care to note what kind of material is acceptable for composting in your backyard, and what structure will work best. See University of Minnesota Extension publications Backyard Composting by Deborah Brown & Carl Rosen and Structures for Backyard Composting by Robert Mugaas & Thomas Halbach. You can also come to a free, hands-on compost bin building demonstration with the Compostadores at the Learning Center on Sat., Aug. 4, starting at noon.

Curbside Composting
Haulers may offer organics recycling at the curb, such as Blue Bag Organics, where organic waste is placed in a certified compostable bag and later placed in a regular trash cart for pickup by Randy's Environmental Services. With organics recycling, a larger variety of waste is accepted for composting than what is considered compostable in your backyard. See what Blue Bag Organics accepts. Also, check out the Blue Bag Organics how-to video or read their guide to curbside composting.

Buy a bag of Blue Bag Organics Premium Compost this summer from the Arboretum SummerHouse! In less than 60 days, the Blue Bag Organics bag and contents break down and are converted to compost.

Blue Bag compost

Other Resources
University of Minnesota Extension publication: Composting and Mulching: A Guide to Managing Organic Yard Wastes by Carl Rosen, Thomas Halbach & Robert Mugaas