Composting 101

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Photo by AdobeStock/fotofabrika 

Everyone likes something that is free and we gardeners are no exception. If you are like me, you have heard about composting, sort of know what it is, not real sure how to make it, so probably haven’t tried it. Being in the midst of fall leaves, I decided that this was the year to take advantage of this “free” nutrient for soils.

I think what scared me off before is that compost isn’t just compost. There is hot compost, cold compost and then there is leaf mold. Yea, this all can be a little intimidating.

By definition, composting is the natural process of recycling organic matter like leaves and table scraps into fertilizer. Anything that grows decomposes eventually and composting is a process that speeds it up by providing the ideal environment for bacteria, fungi and other decomposing organisms like worms, sowbugs and nematodes to do their work. The end result is decomposed matter that looks like fertile garden soil.

Compost allows us to divert waste from landfills and turn it into something useful and also helps to minimize methane emissions form landfills. Garden waste and food scraps make up more than 28 percent of what we throw away. At the same time, it improves soil health and lessons erosion. This “black gold,” how famers refer to compost, can be used by agriculture, horticulture and gardeners.

Types of composting

Cold composting, also known as passive composting, breaks down organic matter slowly but also takes the least amount of effort and maintenance. Anything organic decomposes naturally. This method lets Mother Nature do her job with little interference. No need to worry about the ratio of compost ingredients, aerating regularly or checking moisture levels.

Cold compost is mainly broken down by microorganisms that thrive in oxygen-deprived environments. It is the method of choice if you have little to compost, not much time to put into it and are not in a hurry. This method can take between one and two years, depending on the variables. The downside of this way is that it will not reach high enough temperatures to kill off the pathogens. So, there may be lingering weed seeds, bacteria and other undesirable things left in your compost.

Hot composting is faster and requires more intervention. Nitrogen and carbon must be kept at the optimum ratio to decompose the organic waste.  To accomplish this, the right balance of air and water must be maintained to attract the organisms that thrive in an environment rich in oxygen. Under ideal conditions, the compost may be ready anywhere from four weeks to 12 months. The temperature needs to be kept hot enough to destroy weeds, plant diseases, pesticides, herbicides and larvae or eggs.

Compost elements 

The compost pile needs four key elements to survive, nitrogen, carbon, air and water. Successful composting means using the right combination of materials to get the best ratio of carbon to nitrogen and the right amount of air and water.

The ideal carbon to nitrogen ratio is 25 to 30 parts carbon for every part of nitrogen. If there is too much carbon, the end result will be drier and will take longer to break down. Too much nitrogen will make it slimy, wet and smelly. This can easily be remedied by adding carbon-rich or nitrogen-rich nutrients. The key is getting it just right.

Nitrogen is one of the building blocks of life, an essential element of growth and reproduction in both plants and animals. Good sources of nitrogen are grass clippings, food scraps, coffee grounds and egg shells.

Carbon is essential for all life forms. It provides a food source for the decomposing organisms, helping to keep them alive while they break down waste. Dead leaves, branches, twigs and paper all fall into this category. The general rule is two to four parts brown (carbon) for every one part green (nitrogen).

The decomposers need oxygen and water and, you guessed it, also in the right amounts. Layering the brown and green materials, making sure they are in small pieces and turning often helps to achieve this ratio. If food wastes are included, it will likely be wet enough, with the consistency of a wrung-out sponge.

Photo by Pexels/Sippakori Yamski

Temperature is a huge component too, with the optimum temperature ranging from 130*F. to 140*F. This occurs when waste is broken down at a fast rate. Consistent aeration goes right along with temperature to keep the balance of greens, browns, air and water to create ideal conditions for aerobic organisms to survive. Turn the pile once a week during the summer and every three to four weeks during winter.

To maintain moisture, water the pile or add wet material if it gets too dry and add more carbon if it is too wet.

Start composting! 

So, how do you actually start a compost pile? Add alternate layers of browns and greens, ending with a layer of browns in a dry and shady spot. Ideally, a three-foot cube is the right size for a pile. A large amount of waste is needed for a high temperature pile and any pile larger than five cubic feet will not allow enough air flow.

As you layer, wet as needed. Leave it alone for four days for decomposition to begin. After that, turn it regularly.

Anything that comes from the ground can be composted. The list includes cardboard, coffee grounds, fireplace ashes from natural wood, fruits and vegetables, grass clippings, hair and fur, hay and straw, sawdust, tea bags, wood chips and yard trimmings.

It will be “done” when it is dark and rich, a third the size of the original pile, smells like rich earth and is crumbly and smooth.

Trench composting, another variation, is odorless and invisible since the waste is buried underground.  Simply dig a hole, fill it with organic waste and cover with soil. Earthworms and organisms do the rest of the work. This method is suited for a single operation since it is in a single location.

Leaf mold is essentially composted shade tree leaves. Unlike regular compost, leaf mold is produced through a cooler and much slower fungal-driven process. It is much better used as a soil amendment since it doesn’t have many nutrients. However, it increases water retention by 50 percent in soil, which is a good environment for beneficial bacteria and a good habitat for soil life.

To make leaf mold, either pile leaves in a three-foot wide and high heap or put them in a large garbage bag with holes slit in it. Dampen the pile or contents of the bag and let it do its job, checking occasionally on the moisture level. This process takes between six to twelve months. To speed it up, make sure the leaves are mulched into fine pieces, turn every few weeks and cover the pile with a plastic tarp to keep moisture in.

Compost is a rich and valued nutrient source for gardens and other growing areas. The deciding factor on which method to use is how much time and effort you want to put into the project. The only wrong decision in composting is deciding not to compost at all and not taking advantage of something so good that is free!