by Yvette Henson
I love compost! There is nothing that I can think of that is more beneficial for soil. And, we all know that the secret to great gardens is the soil. While it is more difficult to compost in the mountains, it can be done. The most common frustrations are that it breaks down more slowly in our cooler summers and it often attracts critters like bears and skunks! However, once you have successfully made your own compost, added it to your soil and seen your plants response you will know it is worth the extra management to speed up the composting process. If you still find it too problematic outdoors, you can build a worm-bin or some other indoor composting system. Or once you are a “true believer”, like me, you will do both!
|A 3-bin composting system|
Compost has many benefits. It increases water-holding capacity of sandy soils and improves drainage of heavy (clay) soils. It also decreases the amount of shrink-swell of clay soils. It improves soil aeration, infiltration, tilth and structure and reduces soil compaction and water runoff. It increases soil biota and decreases disease and insect problems. It improves soil fertility and moderates pH. Composting reduces the amount of waste going into our landfills.
There are also a few potential environmental risks from the composting process and overusing compost. Unfinished or immature compost may have phytotoxins that can kill plants. Applying too much over time can build up toxicity of certain nutrients (especially Phosphorous) in the soil. Leachates from compost can contaminate surface water or ground water if located too close to water sources. Odor from improper composting is the most common complaint.
Steps for simple composting:
· Locate to get around 6 hours of sunlight a day, but some shade will keep it moist.
· Use an ‘ideal’ ratio of 25-30:1 carbon to nitrogen when building your pile.
o Carbon is dry, brown or yellow, bulky material like autumn leaves, bark, paper, wood and sawdust. Carbon gives energy to microorganisms but too much will slow decomposition. Nitrogen is green, moist material like grass clippings, food wastes (including coffee and tea grounds) and fresh animal manures.
o Nitrogen increases microorganism populations. Nitrogen materials have high moisture and low oxygen, so too much leads to low temperatures, odor and leaching.
|Nitrogen sources to layer with dried leaves, |
a carbon source, to build compost pile
· Layer your carbon and nitrogen in equal, shallow layers. Top with a thin layer of soil or well-composted manure if desired. Variety is the key!
· Build your pile to at least 4-6’ high and wider.
· Keep moist-- like a damp sponge. If it isn’t moist enough it will break down slowly. If it is too moist it will not have enough oxygen.
· Keep well-drained and aerated. If your pile doesn’t get enough oxygen it will have an odor and it will break down more slowly.
· The best temperature range for microorganisms to do the breakdown process is 90° - 140° F. Too cool slows decomposition; too hot kills beneficial microorganisms (but also weed seeds).
· Turning the pile speeds up decomposition (see the following graph).
|Graph from Cornell Composting Fact Sheet #5|
· You will know your compost is finished when it maintains 70 degrees and larger pieces of what you have added have ‘disappeared’. Chunky carbon like small branches, seeds and egg shells can be screened out.
· Apply your compost an inch or 2 deep and work into the top 8-12” of your garden soil before planting or apply a thin layer as mulch on your perennial plantings
What about those pesky critters?
Personally, I’ve never had much problem with critters in my piles because I don’t add fruit, meat, grease or cooked food. I save fruit for the worm bin. I always cover my nitrogen materials, after adding them with a layer of carbon (bagged leaves or spent straw are what I usually have on hand). Other things that might discourage critters: use ‘bear proof’ containers for composting, electrify your compost perimeter, use repellents (hot pepper spray, etc.) and again, be sure to avoid adding meat, fish, oil, grease or dairy products and maybe egg shells. Not adding fruit or burying it deeply in the pile is something to try too.