Any properly functioning eco-system should be self-supporting — including your urban garden. Crops are planted, those crops use nutrients from the soil and when the crops die, they are recycled into the earth through the process of composting. Composting, used in an urban setting, allows the organic matter and nutrients used by the crops to be returned to the soil. Other types of matter help urban growers to improve their soil, but none provides as many benefits as good-quality compost.
Why Compost?
Try counting compost’s numerous benefits:
- Compost improves the structure of any soil, be it sand, loam or clay. Soils amended with compost will retain more water and drain better.
- Compost containing macronutrients as well as trace nutrients in a slow-release form.
- Compost helps balance soil pH, fosters good soil structure, and improves tilth and fertility.
- Compost loosens clay soils and prevents nutrient leaching by loosely binding nutrients into the soil.
- Compost supports and promotes a diversity of soil life, be it bacteria, fungi, worms or beetles. These soil crawlers help process nutrients and create healthier, more disease- and pest-resistant crops.
- Compost ingredients are easy to come by. What goes into the creation of compost is often the result of your farm’s production—be it garden scraps or kitchen scraps.
- Composting is economical. You will reuse waste instead of sending it to a landfill and reduce the need for other fertilizers and pesticides. The nutrients present on your farm stay on your farm, and they continue to nourish and benefit its future.
Pile It On
When building your compost pile, think in brown and green.
- Browns: These are your carbon suppliers. They are added to the compost pile in a non-living state and have low moisture. Carbon suppliers often take longer to decompose and breakdown into available nutrients.
- Greens: These are your nitrogen suppliers. These are fresh materials added to your compost pile and have a high moisture content. Because they contain many sugars and starches, they quickly decompose.
Aim for a 30:1 carbon-to-nitrogen ratio (C:N) in your compost pile. You can achieve this by building a compost pile with three parts browns to one part greens. So for every five-gallon bucket of fresh, green grass clippings, add three 5-gallon buckets of straw or leaves. (Download a compost materials cheat sheet to help build your compost pile.)
Pay close attention to your initial blend of greens and browns. The ideal C:N ratio will allow for quicker decomposition. It will also lead to an ideal final compost. If you spread a compost with a high C:N ratio on your garden, it will actually rob nitrogen from the soil. On the other hand, if the C:N ratio is too low, the microbes working through the soil will use all the available carbon and release the extra, unused nitrogen into the atmosphere, depleting the finished compost of this essential nutrient.
Compost No-no’s Avoid these materials when building your compost pile.
The Scoop on Poop
Animal manures are possible nitrogen providers, including manures from your goats, chickens or rabbits. Avoid manure from meat eaters like cats and dogs. It’s important to note, however, that manure can be a source of E. coli and other human pathogens, and should be handled with care. Well-composted manures are generally safer than raw manures, but all require special consideration.
Manure must heat to 160 degrees Fahrenheit for a minimum of 15 consecutive days to be considered fully composted. It must be turned at least five times during that period. This temperature, sustained for this time period, kills any potential pathogens.
While uncomposted manure can be used, avoid spreading it where you grow edible crops.
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