The Ugly Truth About Composting: A reality check on how to do it and the many pitfalls in composting.

Composting is great. It keeps waste materials that fill up trash bins out of landfills while creating one of the best fertilizers on earth. But, what most pro-composting enthusiasts, like myself, are hesitant to acknowledge is that it is a tedious, frustrating, time-consuming process that more often than not fails to produce the black gold pictured in gardening magazines. What follows is a reality check about composting:

In theory composting is simple. Combine garden waste products (never meats or fats from the kitchen because they putrefy and attract vermin), mix them together with a little water and let naturally occurring bacteria and fungi break them down into a sweet-smelling, dark, rich, fine soil amendment and fertilizer in a couple of weeks. Sounds great. The reality is that producing good compost requires almost daily work that can be back-breaking and frustrating.

For grass clippings, leaves and all other types of vegetable waste to break down they need to have the proper ratio of nitrogen and carbon, be combined in a pile that's the right size, has the proper texture, an optimum schedule of turning the pile, plenty of oxygen and just the right amount of moisture. Too much nitrogen, such as a pile only made of grass clippings, and it will get too hot resulting in strong ammonia odors, which signals valuable nitrates being lost. Too little nitrogen, such as a pile of leaves, and there won't be enough for the bacteria to live on and it'll just sit there for a year without breaking down very much. If the pile's too small it'll lose heat and moisture too fast and won't be warm enough to support the rapid bacterial growth needed to composting. If it's too large the center won't get enough oxygen and may putrefy. If the texture is too coarse (like a pile of unshredded leaves) too much air will circulate through the pile causing it to dry out. If it's too fine not enough air will reach the middle of the pile and it'll putrefy, resulting in the most nauseating odor you'll ever smell. Too much water and the same thing will happen. Too little and the pile won't be able to grow the bacteria it needs to break down. What all of the above means is that good composting requires almost daily attention to a host of details.

Cut a properly set-up compost pile in half and you'll notice that it's separated into three zones.

The outer zone looses too much heat and moisture for active composting. Inside this is a shell of material coated with white fungi, the sign that it's busy being broken down. This is the zone where temperature, moisture and oxygen levels are just right to encourage decomposition. The inner-most zone of most compost piles doesn't get enough oxygen and like the outer zone, isn't decomposing. In the image above this core is the small yellowish-brown area in the lower center. The core is where purification occurs so the goal of any compost pile design is to keep this zone as small as possible.

Assuming you still want to attempt it, here's the best technique I've been able to come up with from 22 years of organic gardening. Start off with a 50-50 mixture of fresh green material and dry material such as grass clippings and dry, shredded leaves (This provides the approximate 20-1 ratio of nitrogen to carbon most composting experts agree as being optimal.). Prior to combining them, lightly dampen only the leaves so that they feel like a tightly wrung-out sponge. (Fresh grass clippings and leaves that are still moist and piable have plenty of water in them and don't need any more.) You want just the bare minimum of moisture on the dry leaves. A hand full should be able to be squeezed tightly in the hand without water dripping out and not stick together when the clump is released. Mix these materials together so that they are homogeneous and create a light, fluffy pile (don't pack them down.) The pile should be about three feet tall and four feet in diameter; smaller and it'll dry out and loose heat too fast, larger and the center won't get enough air. Use an 18-inch long composting thermometer to check the pile's temperature every day. In three days the hottest areas should heat up to 130 degrees, though the time will depend on the materials used and the outside temperature. If the outside of the pile has dried out, lightly dampen just the dry material as you use a pitchfork to turn the pile, moving the material on the outside to the center of the new pile and the center of the old one to the outside of the new one. Be careful to break up any clods. This may take half an hour of more. Repeat this process every time the maximum temperature hits 130 degrees. (Hotter and too much nitrogen is lost. Lower and the pile takes too long to decompose.) Repeat this for four to eight weeks and with luck you'll be rewarded with a laundry basket sized pile of rich compost.

As the pile gets older and smaller it'll dry out faster so watch the moisture content. It may also heat up slower so several days may go by without having to turn it. Be careful to protect it from rain, which could waterlog the pile and ruin it. As the pile gets more mature it may not reach 130 degrees. Turning every three or four days is still a good idea to prevent clumping and making sure the entire pile gets broken down. Once the pile looks rich, dark and fine-textured it can be mixed into the soil, though most experts agree that it's best to let it rest for several months to stabilize.

Environmental conditions play a major role in composting. In my high-desert location the main problems are very low humidity and high temperatures, which cause the pile to dry out very fast. Areas of high humidity may have the opposite problem and adding water to the pile may cause more problems than it prevents. When composting in winter, even in mild areas of the south, air temperatures may be low enough to rob the pile of much needed heat. In summer the pile may tend to get too hot.

Speaking of heat, some experts advise running the pile up to 160 degrees to make sure weed seeds a pathogens are killed. The problem I have with this is that I feel too much nitrogen is burned off. The resulting compost isn't as rich a fertilizer as one cooked lower and slower. In my opinion, the cooler and slower a pile composts that richer the resulting compost will be as a fertilizer. The 130-degree maximum temperature I prefer is a compromise between speed and quality.

When checking a pile be very careful. Many species of ants love compost piles. You may turn a section over and find yourself ankle deep in an ant swarm

I haven't found compost inoculants to speed up a pile's decomposition. The fact is that garden and kitchen wastes are already covered with all the bacteria and fungal spores a compost pile requires.

I've tried several compost tumblers and in spite of the glowing endorsements that always accompany their ads they have all failed. The most common problems are that no matter how often you turn them they don't let enough air reach all parts of the composting material and they're too small so the pile looses heat too fast. I'm sure many people have had success with them but I've run dozens of tests and the results were always poorer than a conventional pile.

Another composting option is to create larger compost piles and simply let them sit unturned for a year or so. The bottom half of such piles will break down and can be excavated out as new material is added on top. My problem with this is that it invites insect and vermin infestations and much of the nutrient value of the pile may be leached away by rain or surface water. Such piles also take up a lot of room and aren't particularly attractive.

I've come to the conclusion that composting isn't a practical way to dispose of garden wastes. It's great as a hobby for it's own sake, but if you have a large garden or yard it's more work than you may want to invest.

My preference is what is sometimes called sheet composting. This is simply using a rototiller or pitchfork to mix the materials that would go into a compost pile directly into the soil. No further attention is required. Although bacteria and fungi will still attack the materials the real composters will be earthworms, which provide a number of additional benefits for the soil. If tilling is too much effort, I've also found that simply burying the organic waste in a trench covered with six inches of soil also works. Three months later earthworms will have completely broken it down, at least during the warmer months. If the area used for this is to be planted within two months of the organic material's addition, it would be advisable to add extra fertilizer as the decomposing organic mater may temporarily tie up some of the soil's nutrients.

I hope this discussion about composting has helped. It's a rewarding practice that I encourage everyone to try.


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