Composting is the biological decomposition of organic material into humus. The process occurs naturally, but can be accelerated and improved by controlling environmental factors. Garden compost is a mixture of vegetable waste materials which are collected together in a special container and left to rot down. Properly made and well rotted, the compost can be incorporated to the soil and will add nutrients to your plants and helps retain moisture in the soil.
“Every compost pile is a complex eco-system of decomposition experts. “Team Compost” consists of microorganisms and macro-organisms choreographed to take advantage of changing temperatures, moisture, oxygen and pH. Each group has a specialty and as the conditions in a pile change, the main players change accordingly.
The main groups of microorganisms in soil are bacteria, fungi, protozoa and actinomycetes. These tiny little creatures are major players in decomposition. In a teaspoon of compost, you may find up to a billion bacteria, 440-900 feet of fungal hyphae, and 10,000 to 50,000 protozoa. In a similar but more dramatic statistic, one once of healthy soil may contain 54 miles of fungal strands.” (1)
Macro-organisms, such as mites, ants, millipedes, centipedes, sow bugs, springtales, flies, snails and slugs, spiders, beetles, and earthworms, are also tremendously important in the compost pile. They are active during the later stages of composting – digging, chewing, sucking, digesting and mixing compostable materials. In addition to mixing materials, they break it into smaller pieces, and transform it into more digestible forms for microorganisms. Their excrement is also digested by bacteria, causing more nutrients to be released.
Micro- and macro-organisms are part of a complex food chain.
As we all know, it is always necessary to add some organic matter to the soil to supply plants with nutrients and to give the soil a good structure. Fertilizers will provide food but not humus; only rotted organic matter can supply this.
What goes to your pile?
Any soft vegetable material such leaves, stems, grass mowing, flowers and so on. I found this very interesting table at eartheasy.com
|Fruit & vegetable scraps||Nitrogen||Add with dry carbon items|
|Eggshells||neutral||Best when crushed|
|Leaves||Carbon||Leaves break down faster when shredded|
|Grass clippings||Nitrogen||Add in thin layers so they don’t mat into clumps|
|Garden plants||—||Use disease-free plants only|
|Lawn & garden weeds||Nitrogen||Only use weeds which have not gone to seed|
|Shrub prunings||Carbon||Woody prunings are slow to break down|
|Straw or hay||Carbon||Straw is best; hay (with seeds) is less ideal|
|Green comfrey leaves||Nitrogen||Excellent compost ‘activator’|
|Pine needles||Carbon||Acidic; use in moderate amounts|
|Flowers, cuttings||Nitrogen||Chop up any long woody stems|
|Seaweed and kelp||Nitrogen||Rinse first; good source for trace minerals|
|Wood ash||Carbon||Only use ash from clean materials; sprinkle lightly|
|Chicken manure||Nitrogen||Excellent compost ‘activator’|
|Coffee grounds||Nitrogen||Filters may also be included|
|Tea leaves||Nitrogen||Loose or in bags|
|Cardboard without ink||Carbon||Shred material to avoid matting|
|Corn cobs, stalks||Carbon||Slow to decompose; best if chopped up|
|Wood chips / pellets||Carbon||High carbon levels; use sparingly|
When to Start?
“You can start a compost pile any time of the year, but there are limitations during certain seasons. You can build your pile as materials become available. In the spring and early summer, high nitrogen materials are available, but very little carbon materials are available unless you stored leaves from the fall. In summer you start to have garden debris, but your mowing may be lessened due to high summer temperatures. Fall is the time of year when both nitrogen from cool season lawn mowing and carbon from fallen leaves are readily available”. (2)
How to build it?
The Pile should be built directly onto the soil. I recommend to build it in layers of 6-8” deep of vegetables material followed by 1” of organic soil with a sprinkling of lime on top of this to prevent the pile to becoming to acid. Repeat these layers to the height you have decided on. If the weather is dry, spray each layer with water. Add some earthworms too.
“Temperature plays an important role in the composting process. Decomposition occurs most rapidly between 110° to 160°F. Within two weeks, a properly made compost pile will reach these temperatures. Now you must decide how you want to compost. Do you want to add to your pile or just let it continue as is?
If you want to add to your pile, you can do so throughout the growing season and into the winter months. As you add fresh material, you will need to turn and water your pile more often. Monitoring the temperature and turning whenever the piles temperature dips below 110°F keeps your pile active at its highest level, and you will have the fastest breakdown. This means turning the pile more often. This can be weekly and it is work! In reality, the average composter turns their pile once every 4 to 5 weeks. This mixes in the fresh material with the older, adds air to the pile and allows you to add water. With this method, a pile started in the fall, added to and turned the following summer will be ready in late fall of that year or the next spring.
If you are not adding lots of new material, turn and water the pile 5-6 weeks after initial heating. Make sure to turn the outside of the old pile into the center of the new pile. The compost should be ready to use about 3 to 4 months later”. (2)
“Soil conditioner. With compost, you are creating rich humus for lawn and garden. This adds nutrients to your plants and helps retain moisture in the soil.
Recycles kitchen and yard waste. Composting can divert as much as 30% of household waste away from the garbage can.
Introduces beneficial organisms to the soil. Microscopic organisms in compost help aerate the soil, break down organic material for plant use and ward off plant disease.
Good for the environment. Composting offers a natural alternative to chemical fertilizers.
Reduces landfill waste. Most landfills in North America are quickly filling up; many have already closed down. One-third of landfill waste is made up of compostable materials”. (3)
In agriculture, humus is sometimes also used to describe mature compost, or natural compost extracted from a forest or other spontaneous source for use to amend soil. It is also used to describe a topsoil horizon that contains organic matter (humus type, humus form, humus profile). (4)
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