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Composting: Building Healthy SoilComposting: Building Healthy Soil
We layer all these wonderful ingredients in our compost bins. Then, by regulating moisture and aeration, we encourage Nature to provide us with some great compost.
Making compost as a way of recycling nutrients happens in nature when plants and animals die, or animals leave behind deposits of manure.
Decomposer organisms (bacteria, fungi, and insects notably) break down these substances, deriving energy and nutrients for themselves along the way. What remains is available in the soil for plants to reuse.
What should be a wholesome and natural process can become toxic when too much waste material builds up in a single location, such as at factory farms.
The concentration of wastes becomes an environmental problem, and nutrients must be supplied to crops via chemical fertilizers because the natural cycles have been disrupted.
All the more reason to enrich your soil nature’s way!
We are fortunate to have three excellent manure producers next door named Cody, Bueno, and Bugsy. These guys, along with a lovely flock of backyard chickens, provide us with a wonderful source of manure for our garden.
How does the process work?
Four things are necessary: a source of nitrogen-rich plant residues or manure; a carbon source such as straw or coarse plant stems; moisture; and oxygen. If we provide these, the microbes take over and work their magic!
The process is complete when the starting materials have been completely decayed into a dark, crumbly substance called humus. When added to soil, humus improves the drainage of heavy soils, increases the water-holding capacity of sandy soils, and adds nutrients to all types of soils.
If you don’t have horses or chickens nearby, you can use other amendments as sources of nitrogen and carbon. Cottonseed meal and blood meal are two high-nitrogen materials that are often used. These may be available at your local garden center. On the other hand, yard clippings, leaves, and garden waste are typically high-carbon materials. Only about one pound of high-nitrogen material is needed for every 30 lbs. of high-carbon material.
What About Bins?
Most gardeners we know collect organic materials in a bin of some sort, to keep the process of decomposition humming.
Our system consists of three bins: two for the fresh, “active” pile (forked back and forth during turning), and one for the finished product. We also keep our pile covered with a sheet of heavy plastic to further conserve moisture and encourage heating.
For gardeners in places like Portland, however, too much water is often the problem, so a bin made of wire mesh would be just the ticket to maintain air circulation and keep the materials from packing down into a solid, oxygen-deprived mess. When your pile is too wet, it becomes a slimy goo, and odors become a problem, whereas an oxygen-rich environment will produce no objectionable odors.
A DIY bin, whether block or chicken wire or some design of your own, is a good, inexpensive way to make it happen. Keep it simple. A compost bin doesn’t have to be complicated.
On the other hand, especially for those in an urban environment, there are many different systems available commercially.
Most are based on a design featuring a tumbling tub in a frame.
Costs and quality vary, so do a bit of research and take into consideration the volume of organic material you produce.
Turning the Compost Pile
Turning accomplishes three things. It allows you to regulate the moisture content of the materials, watering if too dry, aerating if too wet. It helps “fluff up” the mass, bringing in oxygen. And it helps move material from the outside of the pile where decomposition happens slowly, into the inside of the pile where things happen more quickly.
If you have a wire bin as described above, just pick it up, leaving the wastes behind, and set it down close by. Then fork the material back into the bin, mixing and aerating in the process.
Ready for the Garden
Your compost is ready for use when most of the materials have turned dark, crumbly, and earthy-smelling.
You may want to screen your finished material. We place a framed screen over our wheelbarrow and shovel and shake from the bin, returning larger material for further decomposition. This process helps keep rocks out of the garden beds as well.