Composting at Growing Power
Tuesday, December 8, 2009 at 11:54AM 
It doesn't have much sex appeal, but composting is one of the most important techniques used at Growing Power's 2.5-acre urban farm in Milwaukee, as well as the 30-acre facility in the nearby suburb of Merton. Throughout the two-hour tour I took at Growing Power on Saturday, composting was a constant point of emphasis. It's the reason that Will Allen and his staff have a never-ending supply of nutrient-rich soil and fertilizer, and through composting they're able to divert thousands of pounds from landfills every year.
In the beginning of the tour we came upon a greenhouse where a group of volunteers were just finishing filtering worms out of a wheelbarrow full of soil (below, at left). I've got a worm bin under my kitchen counter, so I'm used to handling worms, but I was still sort of shocked to see the wriggling mass that looked like ground beef in the bottom of the wheelbarrow (below, center). A few minutes later, we bumped into Will Allen, who was busy spreading the worms throughout a big bin of compost (below, at right).
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Composting at Growing Power isn't confined to the worm bins that line the insides of the greenhouse. Large heaps of compost can be found in between the greenhouses and in the small clearing near the livestock at the back of the property. Growing Power collects whole shipments of food waste directly from wholesalers, used coffee grounds from local roasters, beer mash from Lakefront Brewery, and newspapers from the Milwaukee Journal Sentinel.
The most innovative use of compost we were shown at Growing Power was as a source of heat for a small hoop house (below, at left). Compost is heaped in the corners of the greenhouse, and the heat generated by the soil bacteria in unfinished compost is captured and used as a furnace to heat the greenhouse throughout the winter. According to our guide, the center of those compost heaps can reach temperatures of 160 degrees.
-Mark
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