Making black gold


Autumn carries more gold in its pocket than all the other seasons.

~Jim Bishop

Although golden autumn colors are great to behold, those beautiful leaves also possess another type of treasure – black gold, which, when coaxed out, recycle earth’s bounty. “Black gold” is what gardeners call compost, that rich mixture of nutrients and decayed matter that works wonders on all plants.

Leaves contain nutrients that the plants have taken out of the ground through their roots, pumped up their stems and trunks, up to the organs that make food for them…the leaves. The leaves fall and decay. Those nutrients that were trapped in the leaves return back to the earth, where they are reused again by plants.

In a forest, it takes about two years from when the leaf hits the ground to when it becomes part of the soil. A backyard gardener, using a well-managed compost system, can make a fairly large amount of good, rich “black gold” in about three months.

The decaying process is carried out first by microbes. When you see smoke rising from a compost pile in the winter, it’s not because the sun has heated it. The reason is that billions of bacteria are actually dissolving the materials and it is they who are creating the heat. A well-constructed compost pile can heat up to 130 F or more.

Carbon

The microbes feed on the leaves  and other sources of carbon. This could be shredded newspaper, shredded cardboard, old hay, sawdust, small ranches and twigs and pine needles to name a few.

Nitrogen

The microbes need another ingredient – nitrogen –  to grow and reproduce. Nitrogen sources vary: coffee grounds, tea bags, grass clippings, kitchen scraps (but no meat or dairy), aged manure, alfalfa pellets (yes the same used as rabbit food), and cottonseed meal are a few.  Manure from chickens or herbivores is okay to use if it is aged, but carnivore or omnivore manure (pigs, dogs, cats) should be avoided as they may carry pathogens that the composting process will not kill. Weeds should also be avoided, unless they do not have seed heads.

Carbon-Nitrogen Ratios

Although there is a complicated formula to measure the exact  amounts of carbon and nitrogen materials required to start a compost operation, the general rule of thumb is equal weight of carbon and nitrogen. These should be mixed well – a cake mix, not a lasagna.

Water and oxygen

Since all living things need water, add water while mixing the materials. When finished, the compost pile should have the wetness of a wrung-out sponge. Now, it’s ready to start cooking. In two weeks, the compost should be ready to turn. A compost fork is the best way to turn it.

Turning the pile fluffs up the material and adds more oxygen to the mix. To turn, just take forkfuls from one pile and dump them into a second pile. Some gardeners like two or three compost bins to turn one into another. Remember to add water if needed.

After this, turn the pile every week or two. Now, the other, larger organisms will come into your compost pile: earthworms, pill bugs and other detritus-eating animals, further breaking down the materials.

In three months, all these materials will end up as good, organic compost, or black gold.

Types of bins

There are numerous compost bins on the market. Wire bins or bins that are open at the bottom seem to work best because they sit directly on the ground.  That way, earthworms and other organisms can access them. Additionally, open bins allow the air to circulate more freely. Drum bins work, but not as well as open bins.

The benefits of compost:

  • It recycles nutrients back into the soil. One of the things that make plants different from animals is that they make their own food. In order to do this, plants need essential elements like nitrogen, phosphorous, potassium, calcium and others.
  • It improves soil structure. Adding compost helps create “aggregates,” or tiny clusters of soil particles. Soil with a large amount of aggregates is full of tiny (some microscopic) channels and pockets, through which air and water can pass or accumulate in small amounts. Compost also helps with silt or clay soils, breaking them up so air and water can penetrate and plant roots can expand.
  • Compost conserves water. It’s a simple fact. Soil which has compost in it holds more moisture. Soil with five % organic matter can hold up to three quarts of water per cubic foot. Composted soil acts like a sponge. The compost helps soak up moisture. A pound of heavily composted soil can hold almost two pounds of water. Compost also inhibits evaporation of moisture in the soil. In drought conditions, composted soil continues to provide moisture to plants.
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Published by

Bob Dailey

Bob Dailey is a garden writer, lecturer and gardener living in southeast Texas.

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