Now that it’s April, my Master Gardener Program is making a switch from class work to our pay-back volunteer hours. I may not be in the classroom, but the knowledge continues to expand as I assist people at the MG help desk and work in the MG gardens. My blog will continue to be based on my curriculum as there is still so much that I want to share with you! Today’s post is on the value of composting. It might not be a “pretty” subject, but the benefits are numerous, and your garden will love it.
Several of my previous posts have touched on the importance of adding organic matter to soil. Let’s just re-cap some of the benefits that come from adding organic matter to our soil:
- it is a natural soil conditioner, creating humus which is the “glue” to give soil structure
- it makes sandy soil hold more water – structure building
- it makes clay soil drain better – structure building
- it helps to buffer against extreme pH levels
- it is a source of nutrients for plant use
- it is a food source for microorganisms
Composting is a wonderful way to carry out nature’s cycle of growth and decay. The material that remains from the decaying process is organic matter. Ideally, our garden soils should contain 5% organic matter. Mulching 1 – 2 inches each year of organic matter into your soil is a perfect way of sustaining soil health. Composting is free and reduces the amount of yard waste that goes into our land-fills, so it truly is a win-win practice!
There are two composting methods — fast (hot) composting and slow (cold) composting. Hot composting is simply speeding the decay process up by balancing the contents of the pile, water, and air to favor microbial activity. When the conditions are just right, heat is produced and compost piles quickly reach temperatures of 120 – 150F (killing weed seeds and pathogens). Here are some of the basics for hot composting:
- Pile size – the more volume, the faster the decomposition (see chart to the right). A pile the size of 1 cubic yard is recommended for year-round composting.
- What to put in pile – simple vs. complex materials. The ideal carbon to nitrogen ratio is 25:1 – 40:1
- Brown stuff is high carbon
- Green stuff is high nitrogen
- Adequate moisture – water the pile. The material should feel moist, but you should not be able to squeeze water out of it with your hands.
- Aeration – turn the pile (weekly) with airflow in mind. The high carbon matter can act as a bulking agent to make the pile porous and pull outside air inside.
Cold composting is for people who do not have the time to tend to a hot compost pile nor the amount of waste materials to create a large pile. It’s a convenient way to turn wastes into organic matter. Simply mix non-woody yard wastes and food wastes into a pile and let them sit for a year or so. Add fresh wastes by opening the pile in the center and then covering them. Burying fresh wastes, especially fruit and vegetables, help to not attract pests (flies, rats or raccoons). Cold composting does not kill weed seeds, so it’s best to not put weeds in the compost pile that have gone to seed. Turn the pile occasionally throughout the year.
Do you need to build a bin for composting? Containers look neater and shield the compost from pests, but they are not necessary. Piles work well. If you do want to create a bin, make them from materials such as old pallets, lumber, mesh fencing or cinder blocks.
Can manure be used in compost piles? Because fresh animal manure can contain pathogens such as bacteria (Salmonella and e. coli), there is some risk in adding manure to cold compost piles. In hot compost piles that are maintained with the high temperatures, the pathogens are destroyed. If your compost is going to be used on fresh garden crops and you’re cold composting, limit the potential risk by not adding manure into the compost.
What wastes can be composted?
|Fruit Peels and Rinds||Tea Leaves|
|Grass Clippings||Wood Ash|
|Cow, Horse, Poultry Manure (can be with litter)||Corn Stalks|
What wastes should be avoided?
|Cheese or Milk||Noxious Weeds|
|Fat||Cat or Dog Manure|
Composting is such a great way to make the most of what is already headed to the garbage can. With a little thought and effort, composting can become a natural way to recycle wastes and create a beneficial organic matter that will feed your soil. When the soil is healthy, our gardens, flowers and landscapes THRIVE!
Question for the week: Have you tried composting? What were some challenges that you encountered?
Here’s another quick resource for creating a hot compost: http://extension.oregonstate.edu/gardening/how-encourage-hot-compost-pile
Chart on decomposition and compost pile graphic from: http://whatcom.wsu.edu/ag/compost/fundamentals/needs_placement_structures.htm
By Kimberly Bell