By Darbie Granberry
University of
Georgia

To get the best yields of high-quality vegetables, many gardens
need a generous dose of compost now and then. An excellent source
of “slow release” nutrients, compost also loosens tight,
compacted soils and helps them hold nutrients.

So why don’t all gardeners apply compost every 12 to 18 months?
Most likely, because it’s required in large amounts (20 to 30
pounds per 100 square feet), is often sold only in bulk (getting
it home can be a challenge) and isn’t available everywhere.

But don’t be discouraged. It’s still a good idea. And there’s a
simple solution: Make your own.

Many gardeners know compost is good for their gardens but lack a
clear understanding of what it really is. One of the first steps
in mastering the composting process is knowing what is and what
isn’t compost.

Simply put, compost is what’s left of organic matter after it
has been thoroughly decomposed by microbes. The fundamentals
of composting can be gleaned from this short definition.

1. Organic Matter.

It’s no surprise that
composting begins with organic matter. Plants and other
vegetative materials are excellent sources of organic matter.

Readily available, compostable organic matter includes leaves,
grass clippings, twigs, chopped brush, straw, sawdust, vegetable
plants, culled vegetables from the garden and fruit and vegetable
peelings and coffee grounds from the kitchen.

Table scraps aren’t generally recommended but may be used if you
take sufficient precautions to exclude rodents and other animals
from the compost pile.

2. Microbes.

The guys that actually do
the composting are tiny organisms (bacteria and fungi) that can’t
be seen with the naked eye.

Although a number of companies sell “composting microbes,” there
are, fortunately, plenty of them around already. You usually
don’t need to buy them.

Simply mix a few scoops of garden soil (or compost from a
previous batch) into the compost pile. This will provide all the
microbes you need to start the composting process.

Like all other living things, microbes require water and
nutrients to grow and multiply. The organic matter supplies some
of the water. You can mix more into the pile as needed.

All of the nutrients the microbes need can be provided by the
appropriate combination of organic materials. However, if the
nitrogen content of the organic matter is low, add a little
inorganic nitrogen fertilizer.

Some gardeners add animal manure as an organic nitrogen source.
Keep in mind, though, that animal manures may contain pathogenic
microbes that cause human illness.

If you use manure in making compost for your garden, be sure all
of the compost gets hot enough (130 to 150 degrees Fahrenheit)
for several weeks to kill any pathogens associated with the
manure.

The best composting microbes also require oxygen. Fortunately,
there’s plenty in the air. However, as microbes decompose organic
matter, they deplete the oxygen in the pile. So, you have to turn
the pile routinely to provide aeration — more oxygen.

3. Decompose.

The breakdown of organic
matter is the “engine” that drives the composting process.

Organic matter is food for microbes. But they can’t take a bite,
chew, swallow and then digest it, as we do. Microbes release
powerful chemicals called enzymes that digest, or decompose, the
organic matter.

After the organic matter is broken down into small molecules,
microbes absorb these molecules and use them for energy and
reproduction.

This process generates heat which, if sustained over several
weeks, will kill weed seeds, nematodes and other organisms that
can cause disease. This makes composted organic matter much more
desirable than noncomposted materials.

In a nutshell, those are the fundamentals of composting. It’s a
simple process. Try it at home. If you’d like more detailed
information, contact your county office of
the University of Georgia Extension Service.