What is Composting
Our “trash” or Municipal Solid Waste (MSW) is made up of a variety of materials that we throw away once used or consumed to some degree. It's estimated up to 30 percent of what ends up in the landfills is food scrap or yard waste that could and should be composted.
What is Composting
Composting is the process of combining organic waste (from plants) in proper ratios into piles, rows or bins to accelerate their natural breakdown. After being allowed to cure, the result is a stable, soil-like, earthy smelling, dark brown to black material called humus. The finished product is one of the best soil amendments you can find and plants love it! Composting is not a new process, but an important practice that’s been common in civilisations all over the world for thousands of years.
Composting improves soil quality and nutrition. Benefits include:
- Improved soil texture and aeration.
- Improved drainage and nutrient availability in clay soil
- Water loss prevention and nutrient leaching in sandy soils
Soils also require less fertiliser when compost is added because it holds moisture, which saves water, which saves money!
Although there are many ways to successfully produce compost, one of our favourite techniques is the Berkley method, also known as “hot” composting. The steps are easy to remember with this helpful acronym. SMART
Size matters when trying to get your compost pile “hot”. Collect materials until you have about a 4’ by 4’ pile. A smaller pile works too, it just might not get as hot and take a little bit longer.
When building or turning your pile, be sure to add water evenly throughout and in-between layers to achieve even moisture. (Adding water to the top of a pile often leaves some areas too wet and others too dry.) Maintain the moisture in your compost pile so it stays as wet as a damp sponge. If you take a big handful of your material and squeeze hard, only a couple of drops of water should drip out. Any wetter and you might start to develop stinky or anaerobic conditions. Rainwater is best when you have it, but tap water works, too!
The microorganisms in your pile that break everything down prefer an oxygen rich environment. That’s why aeration might be the most important factor to successful composting. By turning your pile regularly, you provide much needed oxygen and redistribute benecial bacteria, fungi and other organisms. Aerating also helps to maintain equal moisture and carbon to nitrogen ratios throughout your pile. In most cases, the more you turn your pile, the quicker you achieve finished compost!
Your C to N ratio (Carbon to Nitrogen) is important to maintain a balance between our browns (materials higher in carbon) and our greens (materials higher in nitrogen) when composting. If you add too many browns, like wood chips, sawdust or paper, you might not achieve the higher temperatures for rapid decomposition and could most likely be left with larger materials in your end product.
On the other hand, too many greens (materials higher in nitrogen), like coffee grounds or vegetable scraps could cause temperatures that quickly rise to levels which the important microorganisms cannot thrive, eventually slowing the composting process.
A ratio of two-parts “brown” to one-part “green” by volume is ideal. One way to achieve this is to layer browns and greens while building your pile in a lasagna type recipe, adding roughly twice as much brown material on top of a layer of green.
Heat is also very important in rapid composting and is supplied by the respiration of the bene cial microorganisms that break down the organic material. To prevent heat loss and allow for the build up of heat, a minimum volume of 3’ by 3’ by 3’ of material is recommended. Decomposing microorganisms function best at about 135°F (57°C) -165°F(74°C), and a good pile will maintain itself at about that temperature range between turnings. A probe compost thermometer is a great way to measure accurately. If temperatures get much higher than 165°F (74°C), it will be too hot and can rapidly cool as some decomposers begin to die off.
What to compost
|Browns ( High in Carbon )
|Greens (High in Nitrogen )
|Dry Leaves / Aged hay / Dried grass
|Vegetable scraps / Fruit peels/rinds / Spent flowers
|Meat, bones, fish or dairy products
|Cardboard egg cartons
|Manure from herbivore animals
|Grease or oil
|Newspaper / Paper Towels / Shredded Paper
|Coffee grounds / Tea grounds/leaves
|Chipped wood / Sawdust
|Left Over Meals
|Pile is wet and smells like rancid butter, vinegar or rotten eggs.
|Not enough air or too much nitrogen or too wet.
|Turn pile and add straw or wood chips. Improve drainage.
|Pile does not heat up.
|Pile is too small or too dry.
|Make pile larger or provide insulation; add water while turning.
|Pile is damp and sweet smelling, but will not heat up.
|Not enough nitrogen.
|Add nitrogen: mix in grass clippings, food scraps, coffee grounds.
|Pile is attracting animals.
|Pile contains meat or dairy products or food scraps are not covered well.
|Enclose pile in 1/4” hardware cloth; cover food with brown materials: wood chips / leaves.
When is Compost Finished? and How to use your Compost
Compost is ready or finished when it looks, feels and smells like rich, dark earth rather than rotting vegetables. In other words, it should be dark brown, crumbly and smell like earth. Most important is when Pile won’t heat up any more, even after being turned. Wait several weeks for it to cure, and it’s done.
That extra time for curing allows the microbes that operate at lower-temperature to put their finishing touches on the pile. It also allows earthworms and other larger organisms which don’t tolerate high heat to move back into the compost.
Compost is ready to use, How to apply:
-- In a new landscape, flower bed or garden; mix up to 2” of finished compost into the top 6’ of soil.
-- For yearly lawn maintenance, apply 1/4” -1/2” of screened compost as a top dressing in early spring.
-- In established beds, apply up to 1⁄2” of compost once a year as a top- dressing in addition to your favourite natural mulch, maintaining 2”-4” of total mulch layer.
-- Utilise a 50/50 mix of sifted compost and sand to fill in low spots or bare spots in your landscape to improve drainage and reduce erosion.
For those who garden in pots, compost can be a useful component of your potting mix. (A mix of equal parts compost, topsoil and sand works well for most plants.)