Compost. It’s a nice word for what happens after nature’s wrecking crew—microscopic bacteria, fungi, and various other small critters working in the dank dark—deal with our organic waste. It’s near religion to some, turning food scraps and waste back into food—and a stinking, disgusting mess to others.
Done right, with the correct ratio of aerated “brown” (carbon-rich material) to “green” (nitrogen-rich material) mixture, it doesn’t stink—much. And at the end of the process it’s actually earthy, pleasant—if you’re a fan of sniffing rich soil. It’ll drastically increase crop yields, especially on our notoriously poor desert soil, or produce green lawns without the chemicals that make an already wasteful practice even worse.
Done wrong, an improper ratio of carbon to nitrogen or under anaerobic conditions—without oxygen—it can turn into a stinking mess attracting bugs and rodents, or produce explosive methane.
Americans, by some estimates, throw away 40 percent of the food they buy. Most of it goes into the garbage can, then out to the dumpster to be hauled to a landfill by the municipal dinosaurs that roar down our streets and alleys every few days, hauling off the evidence of our wasteful society. In landfills, our uneaten food and less degradable trash—plastics, chemicals, heavy metals from batteries, or prematurely dysfunctional Chinese crap—contribute to water and air pollution in an environmentally and economically costly process. It wastes the land it’s on and can pollute the land around it, the water below it and downstream, and the air above it. The U.S. Environmental Protection Agency estimates that 18 percent of U.S. methane emissions come from landfills. And while CO2 is more prevalent, the EPA says, “Pound for pound, the comparative impact of CH4 [methane] on climate change is over 20 times greater than CO2 over a 100-year period.”
We have to burn fossil fuels to get trash to the landfills, and then more to bury it. And, unlike rich and well-balanced compost, it contributes nothing to our well-being by being buried.
It’s a sweltering summer afternoon as University of Arizona students Emily Soderberg and Madeline Ryder motion across acres of farmland in front of them, a stone’s throw from the San Xavier Mission south of Tucson and just west of Interstate 19. They struggle to describe the extent of the ocean of red waste they saw here just a few months earlier, hundreds of thousands of tomatoes, 400,000 pounds, semi-truck loads dumped on this land to be processed into compost. It was the hideously wasteful result of an oversupply that overwhelmed the U.S. market and backed up in the produce brokerage houses of Nogales and Rio Rico last spring.
Nogales is the largest inland U.S. port of entry for produce. The quantities that come through just 70 miles south of Tucson some weeks could supply entire regions of the country. So, giving it to food banks isn’t the whole answer, although Chester Phillips, director of the UA Compost Cats program that employs Ryder and Soderberg, says it is the first call that’s made.
“It was striking and kind of horrifying,” said Phillips, describing the result of the tomato glut at those border produce brokerage houses. Phillips is ASUA’s (Associated Students of the University of Arizona) sustainability program coordinator, the Compost Cats project director, and an avid backyard gardener and longtime composting proponent.
He’s working with others around town to find cold storage for this produce, a place to hold it until it can be distributed, processed, or canned. But he said the food banks can only take so much. It’s in the works, is all he can say for now.
“Composting is great, but let’s feed people first. Composting is not the highest and best use, at least not while people are hungry,” Phillips said.
Meanwhile, there’s a lot of true waste, inedible stuff that makes it into the Compost Cats daily stream. Ryder, a UA conservation biology major, is the sales and marketing head of the growing student-run compost project that started just a few years ago picking up scraps from the Student Union. Soderberg, majoring in sustainable built environments, is a Compost Cats technician. They, like Bruno Loya, an environmental studies and environmental science double major and the Compost Cats safety manager, have paid positions.
After they pick it up, the student crews form the waste into windrows, long triangular rows of compostable material—everything from landscape trimmings and those wasted tomatoes and other produce scraps, to “zoo doo,” the herbivore dung harvested from the elephants, zebras, giraffes, and other vegetarian quadrupeds at the Reid Park Zoo.
Students use big farm machines to churn the contents of the windrows every few days, check the interior temperatures to make sure it’s hot enough for long enough to kill pathogens and weed seeds, and eventually sift the material to sort out the large woody chunks and other pieces that haven’t been broken down. A percentage of the compost is used by the San Xavier Cooperative Farm and the rest either goes to the Community Food Bank of Southern Arizona for its backyard gardening program or is sold to the public to be picked up by the load.
Phillips said Compost Cats quickly grew from picking up waste in the Student Union to servicing some local campus-area restaurants, then a couple of Whole Foods stores, and now is in a partnership with the City of Tucson, taking the separated commercial compostable waste that city trucks pick up from stores and restaurants and composting it at the San Xavier Co-op Farm on Tohono O’odham land adjacent to the San Xavier Mission.
“When I was hired,” Phillips said, “I was basically told, ‘There’s this idea that a few students have had to create compost from the food scraps at the Student Union. Make it real.’ That was about it. At that time we never knew we’d grow into what we are now, partnered with the City of Tucson, the Tohono O’odham … In addition we have brokered deals between Student Union restaurants and the [San Xavier Co-op] farm. It means more local foods [on campus] and exposure for San Xavier. That partnership at San Xavier is a long-term relationship.
“I love the work we do,” Phillips said. “Every semester there are more [students] coming in. We have about 60 students from sustainability this year. It just keeps growing. The environmental bad news isn’t going away any time soon, but there’s a hunger to find something to do about that.”
Breaking down organic waste into compost is not just a matter of saving landfill space, avoiding pollution, or cutting down on food waste, says Emily Rockey, a plant scientist working for local compost producer Tank’s Green Stuff. She said better quality compost significantly improves crop production and noticeably reduces water consumption.
Rockey, director of sales and marketing for The Fairfax Companies, owner of Tucson-based Tank’s Green Stuff, is a University of Arizona plant science grad. “I did a grow study using compost, Tank’s product versus [national brands],” Rockey said. “I planted directly in our compost, compared it to some of these others that you’ll find in big box stores. I used 100 percent compost and [planted] some veggies, flowers, and kale, and the same amount of water and sunlight, no additions. And then I weighed them afterwards.” She found the plants grown in the locally produced compost had, on average, 20 times greater mass.
She attributes some of the success to water retention. “Our compost has varied size particles [which is] important for moisture and drainage,” Rockey said.
She and Fairfax CEO Jason Tankersley also say their compost has more nutritional content because it contains less sawdust and filler than the national brands sold by the bag. And while it sounds odd to brag about manure, Tankersley said it’s a big deal to him that their compost contains 30 percent organic dairy manure from Shamrock Farms.
“It’s very important to me,” Tankersley said, “that we know we’re not using petrochemicals. We’re using organic certified sulfur amendments,” which is added to compost to balance it. “And we use a certified organic microbial mix called BactiFeed, which helps break it down and helps build a healthy environment in the soil.”
Tank’s Green Stuff is Tucson’s largest local producer of commercial compost; it’s sold by the bag at Ace Hardware stores and nurseries in Tucson, Green Valley, Sierra Vista, and Bisbee, or delivered in bulk by truck.
The closer composting gets to the source of its components and the place it will be used, the less waste—and cost—added by transportation and packing. But there are obstacles. Composting in backyards and at school and community gardens is ideal, but it requires some understanding of the ratio of inputs needed, which aren’t always consistently available on a small scale.
Successful aerobic composting requires a proper mixture of what is referred to as “brown”—leaves, straw, newspaper, sawdust and wood chips, corn stalks—and “green”—food scraps, vegetable and fruit scraps, fresh grass and weeds, coffee grounds, chicken manure, garden debris such as dead flowers, plant leaves, and stems. Brown is high in carbon, while green is high in nitrogen; you want a carbon-to-nitrogen ratio of between 25 and 30 parts carbon to 1 part nitrogen. If there’s too much carbon, decomposition slows down to a near halt. A pile of dry wood can last for ages under certain conditions. And if there’s too much nitrogen, you get a stinking mess.
Most stuff we’re likely to throw into a compost pile, bin, or drum will have some carbon and some nitrogen—and probably not a 30 to 1 ratio. Hitting the magic ratio is trickier than throwing in 30 handfuls of leaves for every handful of table scraps.
There are dozens of books and pamphlets on composting, and nearly as many devices that promise to make it easy. The best are easy to roll, tumble, or rotate so you can mix the contents frequently.
“I got into gardening because I’m named for a victory gardener who fed eight people, my mother’s grandmother Martha,” says Martha Retallick, a Tucson photographer, copywriter, and web designer. To Retallick, composting is a natural part of gardening.
“I started it out by using five-gallon pots and sticking my hand in to mix it up,” Retallick said. She recently switched to a rotating horizontal 55-gallon barrel composter she bought off Craigslist. “My brown material is what falls from my mesquite tree. The green material is what comes out of the kitchen.” Some of it she chops up to speed up the process—usually about three months for a load to turn into usable humus.
In our dry, hot Arizona air, she said keeping the mixture moist, as well as turned, is important. “Otherwise it’ll dry out and instead of compost you’ll have an archive.”
Moses Thompson’s a Pied Piper, but with kids instead of rats. The students of Manzo Elementary follow him around the school’s former courtyard even after school, shouting, “Mister, mister!” They want to check the worms in the vermiculture tank, pick produce, or feed bugs to the chickens in the school’s center courtyard-turned farm.
They’re into Manzo’s—Thompson’s—gardening program, even the grubby sometimes-smelly composting part of it. Organic egg-producing chickens, a greenhouse with a jungle full of tilapia-fueled aquaculture plants, a garden of radishes, kale, and other healthful greens—and bins of ripening compost. There’s also a big, oblong galvanized stock tank where a herd of red wiggler earthworms turns cafeteria food waste into soil in short order.
The kids love the worms, said Thompson. They sift the worms’ output, the byproduct of the mixture of food scraps and straw and wood chips donated by a local landscaper, removing the worms and the larger undigested pieces. They move that from the dark, rich soil, back into the compost production line, where the worms continue the process with a fresh load of input material.
“We use all the gardening we do here academically,” he said. As the kids sift the worms out of the coarser, unfinished material, they keep track of the worm population. A white board has nine groups of four vertical lines, each with a diagonal slash through it, plus two more vertical lines. “We’re teaching the kids to count in groups of five,” says Thompson of the day’s census of the 47-worm herd.
But worm ranching is a richer school’s game. These days, Thompson said, red wigglers—the most efficient species for vermiculture—go for $20 a pound, plus shipping. So vermiculture takes a back seat to bin composting. Each school day students add carefully sorted lunchroom waste to one bin.
“The most responsible thing you can do with your food is eat it,” Thompson said he tells the students about the lunch program vegetables and fruit served at Manzo. “Even composting is not a good use of those resources, the water that was used, the transportation, the packaging. The best return on school lunches needs to be in nutrition to the kids. Composting is only a better option to sending it to the landfill.”
Thompson started out as a counselor at Manzo in Barrio Hollywood, an old Tucson Unified School District school between West Speedway and St. Mary’s Road; he now runs the gardening programs for 10 TUSD schools. He has a master’s degree in counseling from Iowa State University. Thompson said the school’s gardening and composting program is a natural match for counseling, and that’s how Manzo’s program started. “Kids associate the office with stress; it’s where you go when you’re in trouble. But out here, they’re on more of an equal footing. They have buy-in,” Thompson said.
There are eight bins for compost. Waste, mostly food scraps from the cafeteria, are added each school day. This is all done by the kids, down to churning the compost with pitch forks. “We teach tool safety,” Thompson quickly points out. Each of the eight compost pens is churned every school day. But before that, the temperature of each is measured by a student and the internal temperature entered on a log. Internal temperatures need to get up to about 160 degrees to kill seeds, undesirable bacteria, and pathogens.
Thompson said the produce and eggs are sold to Manzo students’ parents at a discount, since the students labored to produce them. The rest is sold at a Manzo farmers’ market.
Big composting operations like the UA Compost Cats and Tank’s Green Stuff, the restaurants and grocery stores that segregate their compostable trash and pay to have it picked up, and the little school programs and community gardens all add up. But the organic waste of a metropolitan area of one million dwarfs the rest. And right now, there’s no one answer.
The city is working on that.
The City of Tucson’s Environmental Services Department took over collection of compostable material from Compost Cats’ 14 campus-area businesses in late June and is continuing to add businesses, said Sherri Ludlam, a plant scientist working on the program. But she said the city collection department is only adding businesses in locations roughly contiguous to the current route. Ludlam said they have extended the twice weekly commercial pickup route beyond the UA and downtown corridor up North Campbell Avenue and over to Amphi High School.
Staff members of the UA’s Compost Cats are training employees to avoid contaminating the source material at businesses where they collect future compost. When a standard city refuse truck drops off commercial compostables at the San Xavier Farm twice a week, Compost Cat workers have to pick through the long windrows of compost material to remove nonbiodegradable debris like plastic produce baskets and product stickers.
Ludlam said the program is a one-year experiment that will be evaluated to determine whether it will be terminated, continued, or expanded. “We have to figure out what it’s costing us [to provide the service]. Since we’re a department of the city government, we have to cover our cost, but we don’t have to make a profit,” Ludlam said.
The city charges commercial customers $20 a month for once-a-week pickup and $40 a month for two pickups per week, no matter how much material they leave out. Ludlum said some customers have left as much as two tons for a single pickup. And she said one prospective customer has the potential to have as much as 10 tons per week.
Asked if there have been any surprises during the first few months of the new service, Ludlam said, “Surprises? Well, I don’t think it smells as bad as you’d think in Arizona heat. That’s unless it’s contaminated with protein. And I never gave much thought to how much it weighed.” Ludlam said the compostable waste is remarkably dense, so heavy that containers can’t be filled to the top.
She and other city environmental services staffers said there has been no discussion of expanding compostable pickup to residential customers.
“Locally we do have Scraps on Scraps,” Ludlam said, referring to a new company offering residential pickup as a subscription service.
Scraps on Scraps provides customers with an airtight and watertight five-gallon plastic bucket that the company picks up every other week for a $13 monthly fee. They take the full can and leave a clean empty can. For $7, residential customers can drop off a bucket of compostable material every other week at the Thursday Santa Cruz Valley Farmers’ Market at the Mercado San Agustin or the Sunday Heirloom Farmers Market at Rillito Park. For just $2 a month more, they can drop off a bucket every week. The collected compostable material is turned over to the Community Food Bank’s Las Milpitas Farm for composting.
Since the business started in January, Shannon Sartin, one of the founders, said it has been adding an average of two customers a week, reaching a total of about 60 residential customers. She expects to add some commercial customers later in the year.
With roughly 100 U.S. cities already providing curbside composting, a local residential program would seem inevitable. But the discussion isn’t yet on the table in Tucson, according to Cristina Polsgrove of the city’s Environmental Services Division. They get asked about home composting a lot, she said. “The answer is if we put another container out there, that’s going to increase costs.
“There’s a fixed cost with just putting the truck out on the street. It would have to be done as a separate pickup. Our trucks we have now have only one compartment. With recycling, you can get everybody. But our costs are based on those two containers. We don’t have a way to process those materials,” she said. “The question becomes, do enough customers want to pay an additional fee to make it economically viable for the customer and our department? Do the Compost Cats have the ability to take on that [volume] of processing?” ✜
Dan Sorenson is a longtime Tucson newspaper reporter, freelance writer, musician, and more recent gardener.
A near constant line of landscaping crew trucks pulling those familiar, rattling metal mesh-sided trailers rumbles into Tank’s Green Stuff’s East Side lot throughout the day. The company’s huge lot and landfill is in the 7300 block of East Speedway, next to and behind the East Side City Hall. The landscapers are there to dump the grass, hedges, and branches they’ve accumulated in the big trailers—which are also stuffed with leaf blowers, rakes, shovels, and the other implements for reversing the effects of photosynthesis run wild in the desert sun. It’s an endless cycle here, as long as the water and sun hold out.
Tankersley’s crew weighs the stuff being disposed of, charges the landscapers $30 a ton, and then, on the way out, sells them some compost or mulch made out of the very stuff they were paying to drop off. Brilliant.
It’s an all-around good deal. It saves the landscapers a longer haul to an outlying landfill, and they can pick up supplies they’ll need anyway. It’s actually just a commercial reflection of the way all composting works, with a little charge for value added. You take a plant, give nature a little help breaking it down, and it produces a nutritious base to grow more vegetation.
At first, Tankersley said, the beautiful financial simplicity of it didn’t work quite that way. But now, just over three years into the Tank’s Green Stuff story, it’s so popular, they’re having a hard time keeping up with demand.
Their product kind of sells itself, he said. Compost and mulch help conserve water on landscaping while promoting plant growth.
While he’s started doing big volume business with some golf courses and commercial landscapers, he credits gardeners with much of Tank’s success. “It really started with the gardeners,” he said. “I got on Facebook and started communicating with Tucson Backyard Gardeners.” Now, it’s common to see members of the gardening group recommend Tank’s when a newcomer raises a question about how to enrich a garden plot or just where to find compost.
“We got into a couple of the Ace Hardware stores and people saw the benefits, the water savings, stopped using fertilizer and things that kill the healthy soil. A lot of these compost products you see out on the market are almost solid sawdust packed with fertilizer, basically toxic to the soil in the long run.”
Beyond not using sawdust and other non-nutritious fillers, Tankersley said they also avoid using cactus and palm in the compost mix.
Tank’s compost is available by the bag or for delivery in bulk at $34 a cubic yard, with a $75 per load delivery fee. ✜