Building Arcadia’s Own Local Compost

By Marsha Johnston, Arcadia Farm Education Volunteer 

Upon arriving at Arcadia to direct farm operations last year from his job as an instructor at the Farm School in Massachusetts, Stephen Corrigan quickly realized that he would have to create his own field-scale compost production in order to restore the tired soil enough to produce a large volume of vegetables. The bin compost system in the Groundhog Garden was great for teaching, but could simply not produce the quantity of compost he needed.

“The rule of thumb is 10 tons of compost per acre for an established garden,” says Stephen, who has taught composting at the Farm School in north-central Massachusetts and elsewhere. “But the land here is heavy clay, and has not really been worked in a while, so it needs more love. We’re trying to add at the rate of 20 tons per acre.”

Arcadia had been buying compost, but to buy twice as much would have broken the bank. Instead, on a sufficiently discrete spot on Arcadia’s lower field last December, he created the first pile out of 30 parts bedding and one part manure from the neighboring horse stables.  By March, it was ready to spread. While manure from grazing animals like horses, cows and sheep is fine, Stephen cautions that compost should never include waste from carnivorous animals such as dogs and cats, to avoid introducing pathogens.

“The most important rule is the 30 [parts carbon] to one [part nitrogen] ratio, where brown is carbon and green matter is nitrogen,” Stephen says. “It’s the one most people don’t get right. You can’t just throw out a bunch of kitchen scraps and expect to get compost. That’s why it gets a bad reputation, because if you do that, it will smell horrendous.”  

For Arcadia’s second batch, he used horse manure plus food scraps from the Neighborhood Restaurant Group Central Commissary and coffee grounds from Buzz Bakery in Alexandria and Peregrine Coffee. Living in Alexandria, Stephen picks up the grounds from Buzz Bakery, while Arcadia’s Mobile Market picks up from NRG and Peregrine, which are both near its route, in Union Market. “We’re layering it all with leaves from the city of Alexandria and spoiled straw from Mount Vernon,” he says, adding that clean newspaper and brown paper are also good brown matter components.

Eggshells are a good nitrogen element, he notes, but all fats, butter, oil, dairy and meat should be kept out.  Citrus fruits are not great, as the oils in the rind slow decomposition, he said, but his experience at Arcadia composting mostly zested citrus has shown that citrus flesh is workable.  

Thanks to Stephen, Arcadia now produces enough organic compost to meet its growing needs, while keeping otherwise useful organic matter out of landfill. He'll be teaching our June 1st Workshop on How to Compost so join us to learn about building your own backyard compost.