Hello Roger,
The University of Northern Colorado, where I work, is considering composting our own food waste, as well as yard and other organic campus waste. The point to me is; why spend the energy to ship food waste away to be composted. Compost made on campus could be used on the grounds and eventually used on an on campus market garden, with produce sold in an on campus farmers' market. The emphasis on in-vessel composters seems to focus on the mechanical rather than the biological nature of composting. What is your opinion of aerated static pile composting, using natural convection, not air flow forced by blowers, or even perforated pipes? The heavy layer of carbon material all around the compost pile seems to stop smells and pests, absorb liquids, and prevent freezing, allowing year round composting without additional heat needed.

Donn Kuntz, Dining Services, UNC

Hi Donn,

If you have the ability to compost on-site and use the finished compost on site, I think that is often the best way to go.

However, doing so requires some space, especially if you are doing windrow or static pile composting. For a lot of schools, especially those in more urban or suburban environments, they may not have the land on campus to dedicate to composting. If you are going to ship off site to an off site composter, I am curious how many are focused on making a high quality compost that can be used on agricultural soils to replenish the soils that are providing the food crops to your campus. Saw an interesting presentation from a grocery store chain out west that was essentially back-hauling food waste from the store "spokes" back to a central hub. I have since been intrigued to see if someone that is getting local food delivered direct from a farm could utilize that back-hauling model to return that food waste to the farm for composting. The advantage of such a model is that the farm may already have the equipment and end-market needed to make that composting operation viable.

I have unfortunately seen some compost operations that are more focused on diverting stuff out of the waste than on the quality of the finished product. The result is unfortunately too often a compost that is not used as the nutrient-rich soil amendment that we typically think of compost as, but rather as essentially alternate clean fill or alternate cover at a landfill.

In terms of static piles, I have read some evidence that a properly managed static pile will retain more nutrients than a constantly turned pile. And I agree with you about having enough carbon in the pile to prevent odors. One thing you should consider though if you are doing static piles is making sure you have an oxygen probe to ensure that your convection is actually happening. At one of my former schools, we had a lot of static piles that were not effectively managed and the centers went anaerobic. There was enough carbon on the outside that it didn't stink until we finally went to turn them and check them, but they sure did stink then.

Hope this helps.