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GUIDELINES FOR MAKING GARDEN COMPOST
I've mentioned before that our home doesn't have a garbage disposal and that we recycle all of our fruit and vegetable scraps, eggshells and coffee grounds in our compost pile.
My composting system consists of two side-by-side 4-foot square bins. With a two-bin system, one bin contains compost that is nearing maturity, while the other constantly receiving fresh kitchen scraps, leaves, grass clippings and leftover soil from expired potted plants. Decomposition can be accelerated in both bins by turning the contents frequently.
If I could start over, I'd build a system with three bins and always leave one bin empty. This would make turning the pile easier, since a full bin could simply be shoveled or forked into the empty bin. With my present system, I have to turn and stir the pile inside the bin and it's a lot of work. Consequently, I don't turn the contents as frequently as recommended and am only able to produce one crop of compost a year. This year's compost amounts to approximately 120 gallons - I offer that form of measurement because I store the finished compost in old 30-gallon garbage cans.
A Master Gardener friend of mine did some research on composting coffee grounds, which is a daily addition to my compost bin. Turns out coffee grounds are an excellent compost ingredient. When added to a "worm composting box," the worms readily digested the coffee grounds and made excellent compost.
Coffee grounds have a carbon-to-nitrogen ration of 20:1, roughly equivalent to that of grass clippings. After brewing, coffee grounds contain up to 2% nitrogen. The Carbon to Nitrogen (CN) ratio determines how easily microorganisms can break down the organic waste in a compost pile. Microorganisms (fungi and bacteria) use carbon for energy and nitrogen for protein synthesis. These organisms need large amounts of nitrogen such as is found in fresh grass clippings, vegetable scraps and cattle manure. By contrast, leaves, pine needles, wood chips, sawdust and corncobs contain large amounts of carbon.
The CN ratio of grass clippings is 17:1, compared with leaves (54:1), hardwood bark (223:1), sawdust (442:1). Other high-nitrogen ingredients include fresh manure (19:1) and vegetable matter (12-20:1)
A CN ratio of 30:1 is considered optimum for microbial activity. The CN ratio is controlled by what materials are placed in the compost pile. Too much carbon keeps the pile cool and slows down the action, while too much nitrogen makes the pile stink like ammonia gas. You'll eventually get compost but it takes longer.
Why bother with compost? My Master Gardener friend says compost has more benefits than a good retirement plan. When added to garden soil, compost:
- Moderates soil temperatures.
- Retains soil moisture (especially on droughty soils).
- Reduces nutrient leaching due to its increased cation holding capacity.
- Reduces soil compaction.
- Encourages more efficient nutrient uptake.
- Provides nutrients to plants.
- Adds buffering capacity which resists changes in soil pH.
According to the University of North Dakota Extension Service, the finished compost from a properly constructed and maintained compost pile will contain the following:
10-15% water
10-20% organic matter
0.8% nitrogen
0.45% phosphorus
1.45% potassium
1.25% lime
0.3% magnesium
Texas A&M researchers estimate that coffee grounds, tea leaves, vegetable trimmings and fruit wastes are produced in an average household at the rate of from 0.2 to 0.9 pounds per person per day. In a four-person household, that amounts to 292 - 1,314 pounds of material per year. And that's a lot of good stuff for the compost pile.
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PUTTING DOWN ROOTS:
A Delightful Blend of
Gardening Wisdom, Wit
and Whimsy
$10 + $2 for shipping
by Cliff Johnson |
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