Don’t toss in wet, packed grass clippings and expect black gold
“Essentially a good compost pile needs four elements: some carbon-containing material, nitrogen containing material, oxygen and moisture,” says Hinks.
Add “browns” (soil, twigs, branches, pet hair, coffee grounds, floor sweepings = carbon) and “greens” (grass clippings, vegetable parings = nitrogen).
What about oxygen? “If you’re adding bulky materials, there should already be enough air [between the branches and twigs] to ensure good aerobic processing,” says Last.
Aerobic digestion occurs when there is oxygen present, which is a good thing. Anaerobic decomposition is what creates the smell while items rot, when there isn’t sufficient oxygen.
How do you fix smells? “I add a bit more brown stuff and give it a bit of a stir,” says Last. “If it’s not breaking down well, I first check light and water levels. If both are adequate, I add a bit more of the green stuff.”
Moreover, explains Hinks, there’s a formula to help us: “Balance ‘wet’ materials, such as vegetable and fruit scraps, that are high in nitrogen with ‘dry’ materials, such as dead leaves and straw, that are high in carbon. Ratio is 1 part wet to 2 parts dry.”
Don’t turn too much!
Turn, turn, turn? Not! Both master gardeners challenge this mantra. Says Hinks: “The important thing is the availability of oxygen to aid decomposition. This is why people turn their compost piles. But if you successfully layer dry and wet, turning is probably not necessary.”
“Effective composting is a bit like cooking,” Last adds. “The recipe and method can and should be adjusted according to what you want to feed your plants. Beneficial bacteria add nitrogen to soil, which is great if you are top-dressing a lawn, but nitrogen in flower beds can promote leafy growth without necessarily enhancing flower and fruit production.”
When compost is turned frequently, tiny thread fungi called mycelium are constantly being broken and will not develop well, says Last. “Mycelium forms symbiotic relations with plant roots, especially on woody plants, where it enhances flower and fruit production.”
Don’t get hung up!
Hinks encourages us, saying: “There are many ways to compost that are successful.”
Understandably, his colleague agrees. “The science and chemistry behind composting and soil biota can be extremely complex, but home gardeners don’t need to know all the details,” Last adds.
Now, who’s for giving black gold a go?
Image by cotesebastien/istock