When making your own compost, avoid using diseased plants

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By Dennis Morgeson

Composting is a controlled natural biological process where bacteria, fungi (microbes), and other organisms decompose organic wastes.  This is a clever scientific definition of composting but basically it’s allowing organic material to decompose into humus or compost or basically “dirt”.

Compostable materials include leaves, grass clippings, pine needles, straw, and non-woody plant clippings such as weeds and vegetable plants. It is best not to use diseased plants from the flower or vegetable garden for composting if the compost will be returned to the garden. It is a good idea to have two compost piles, one for vegetable waste and one for flower garden waste.  Put flower waste compost on the vegetable garden and vegetable waste compost on the flower garden.  This is because a small compost pile at home may not heat up to high enough temperatures for a sufficient period of time to kill the disease organisms.

Also, it is best to avoid composting weeds with many seeds, since the seeds may not be killed during composting in a home situation. Woody materials such as branches, logs and twigs may be used, but chip them into one-quarter inch or shorter pieces in order to make these materials break down faster. Add a little fertilizer or manure if adding wood chips. They take a lot of nitrogen to break down and the fertilizer will heat up the bacteria and get them off to a good start. Kitchen wastes, such as coffee grounds, washed egg shells, and vegetable scraps, may be added. However, meat, bones, whole eggs, and dairy products should not be added since they may attract rodents and other animals.

Feces of pets and humans should not be added to the compost pile because diseases from these feces can be transmitted to humans. It is good however, to add manure from livestock.  Don’t use “green” manure unless you have at least as much dry ingredients to mix with it.

A thin layer of soil or finished compost should be added to the pile to serve as a source of microbes that will decompose the organic material. You don’t need those expensive compost starters you see advertised in catalogues and at garden centers. There are plenty of microbes in soil and compost to do the trick.

There are four key factors - aeration, moisture, particle size, and carbon-to-nitrogen ratios that are involved with successful composting. These factors are associated with maintaining the activity of microbes (bacteria and fungi) that break down organic materials into compost. If any of these four factors are limited, the process of decomposition slows, stops, and or becomes smelly. A healthy compost pile does not emit a fowl older.

Aerate the compost pile by turning it with a garden fork or shovel. Aeration adds oxygen, which is essential for microbes to break down organic wastes efficiently. Frequently turning the pile during the initial stages of decomposition increases the activity of the microbes, thus reducing the time and space required for composting. If the pile is turned infrequently, the composting process will take longer.

Turning the pile also helps it reach a higher temperature. Heat, ideally between 90 and 140 degrees Fahrenheit, helps destroy some weed seeds and diseases. The smallest size for a compost pile is 3 feet by 3 feet by 3 feet or 1 cubic yard, otherwise, the pile will not heat up properly. Check the interior temperature of the pile with a thermometer or with your hand. Ninety degrees Fahrenheit feels comfortably warm. One hundred forty degrees is too hot to touch for more than ten seconds. A compost thermometer is a good investment, after all who wants to stick their hand into unfinished compost?

Moisture is required for microbial activity. Water the layers as you add them to the pile.

The pile has the right amount of moisture if about two drops of water come from squeezing a handful of the material being composted. You can add water while turning the pile if it is dry.

If the pile is too wet, turn the pile frequently or add more organic material. Excessive moisture replaces air spaces, causing a lack of oxygen in the pile. Thus killing the bacteria and slowing the decomposition process.

Another point to remember is that the smaller the particle size in the compost pile, the faster the material will be turned into compost. Smaller particles have a larger surface area that microbes can attack. Shredding materials before adding to the compost pile also reduces the initial volume of the pile.

In a compost pile, the ideal carbon to nitrogen ratio (C:N) is 30 parts carbon to 1 part nitrogen (30:1). Carbon serves as an energy source for the microbes, while nitrogen is required for growth. Materials such as straw and woody material are high in carbon, while livestock manure and grass clippings are high in nitrogen. An ideal C:N ratio is achieved by mixing high nitrogen material with high carbon materials.

If the amount of nitrogen in your pile is low, you can add livestock manure or blood meal as an organic source of nitrogen or a fertilizer with high nitrogen content.

Lime does not have to be added to the pile. The addition of lime to the compost pile converts ammonium nitrogen to ammonia gas, which leads to the loss of nitrogen. Finished compost usually is slightly alkaline without the addition of lime.

Finished compost will have an earthy smell and look like dark-colored soil. It can be produced in three months or more, depending on the amount of time spent meeting the needs of the bacteria and fungi that break down the organic materials.

If you have any questions about compost, call the Washington County Extension Office at (859)336-7741.