Friday, October 23, 2009

Composting For the Home Gardener

Compost includes 4 basic elements including air, water, carbon, and nitrogen.

There are two types of composting, aerobic and anaerobic, meaning with oxygen and without.

Anaerobic composting (without air) is a cold process, takes as long as two years to produce usable compost, and DOES NOT remove soil pathogens, bugs, and weed seeds. This method is NOT recommended for the family garden for the reasons stated above, plus the fact that it creates an unsightly, smelly mess in your yard that attracts rodents, etc.

Regrettably, anaerobic composting is what 99% of family gardeners usually end up with, because of lack of education and/or effort.

Aerobic composting must sustain temperatures of approximately 140 degrees Fahrenheit for three weeks minimum, which kills most soil pathogens, bugs, and weed seeds. It requires a constant supply of air throughout the pile, in order to provide oxygen to the microbes that digest and thus decompose the raw materials into usable compost.

Therefore, the pile should be thoroughly turned daily, and if all other elements are present in the right proportions good compost can be created in as little as one month.

Water is also necessary, but not too much at one time. The pile should be moist - like a wrung-out sponge - but not wet.

Carbon is used as the energy source, and most of the pile should consist of carbon. Common high-carbon ingredients include dry leaves, straw, and corn stalks. High-carbon ingredients will contain more than 30 times as much carbon as nitrogen - sometimes MUCH more - and are often called "browns".

Nitrogen is needed for the proteins that build the microbes' bodies. Ingredients with the most nitrogen are usually green, moist plant matter such as leaves, or an animal by-product like manure. Nitrogen-rich materials - often called "greens" - usually will contain carbon and nitrogen in a ratio close to 20:1.

NEVER use manure from carnivores, and even cow manure sometimes contains e-coli, which can cause sickness and even death. Therefore, any manure should be used with extreme caution.

For efficient decomposition you need a carbon/nitrogen (C/N) ratio of about 30:1. If you have too much nitrogen your pile will smell, because the excess nitrogen converts into an ammonia gas. If there's too little nitrogen you will not sustain the necessary heat, plus the pile will break down very slowly.

Fresh grass clippings will have a C/N ratio of about 20:1, so mixing grass clippings and old leaves - one part clippings and two parts old leaves - will generally give you a good C/N ratio.

Unless it's contained in a Compost Tumbler or other container in which it can be turned easily while retaining the heat, you should start with a compost pile of at least 1 cubic yard, in order to have sufficient material to retain the necessary 140 degree heat for 3+ weeks.

Do it right, and you can have material that will improve your soil tilth, and even provide some (unknown) amount of nutrition for your plants.

Or save yourself the time and effort and give your plants a balance diet of natural mineral nutrients, as contained in the Mittleider Pre-Plant and Weekly Feed mixes, which you can mix yourself from materials purchased at your nursery or farm supply store.



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