How long does it take for a compost pile to decompose?


Picture of a compost pile

More organic gardeners nowadays are deciding to generate their compost instead of buying it from gardening stores. Their friends are composting, so they want to. Here’s what gardeners need to know about how to make compost.

Compost can take anywhere from 1 to 12 months or more to decompose. The time depends on when the compost pile was built during the year, whether carbon and nitrogen ingredients were included in the proper balance, if the materials were layered correctly, and how well you maintained the pile.

Composting isn’t physically difficult to do. But there are several aspects involved that most new composters aren’t aware of. Read on to learn more.

How Long Does Compost Take to Decompose?

Composting Times Vary

When I manage my compost pile in the spring and summer by adding the correct materials and by watering and turning it regularly, it takes 2 to 4 months for the compost to “ripen.” The coldness of winter slows down the process considerably. It may take six months for the same amount of decomposition to occur then.

For instance, I prepare a compost pile in the fall to have humus available for use in the garden in early summer. It does take that long for the aerobic bacteria to grow and do their work. The reason? I can’t turn the compost as often due to cold weather.

But, if a pile consists of large chunks of unshredded paper, wood, corn husks, vegetables, and the like, it will take over a year to make this compost decompose–winter or summer. Smaller chunks always take less time to turn to humus.

Speeding Up the Process

There are times I want to hurry the process of compost decomposing along. That’s when I add worms to the mixture. In less than a month in the high summer, their movement and digestion of organic waste have turned my compost pile into humus.

The proper mixture of carbon-rich and nitrogen-rich materials will also significantly speed things up. Aerobic microbes chew up and digest the material. This process heats the compost pile. There’s a surprisingly high number of calories in the production of compost.

The best way to make the microbes happy is to add manure. I add fresh manure to the top of the pile in October, knowing it will age well over the winter. I add aged manure to my new compost pile in the spring. This nitrogen-rich material helps aerobic microbes multiply rapidly.

Slowing Down the Process

Some gardeners use what I call the cold composting technique. They’ll pile in materials and let it sit for years with no turning whatsoever.

One gardener I know had five compost piles going, one per year. He’d remove the fifth-year hummus and put it on top of his garden bed. It crumbled nicely, like dirt. He’d use the compost from the other piles in rotation each spring in later years while renewing the one he just used.

How to Make Compost

Organic Decomposition

Composting is simply the process of organic material decomposition. Organic matter breaks down on its own. Humans create compost by mixing a variety of organic matters in specific amounts.

Over time, the mixture turns into nutrient-rich fertilizer, superb for gardens.

Compost Ingredients

I could add almost any organic material to my compost. But, I make it a policy to omit some animal-produced food scraps such as dairy and meat. I also refuse to put any manure or feces produced by humans or carnivores. It’s loaded with dangerous pathogens.

Instead, I use manure from herbivores, such as cows, horses, sheep, chickens, and rabbits. Herbivore manure makes a superb nitrogen source for compost.

I add the following ingredients to my compost: Fruit and vegetable scraps, eggshells, pine needles, coffee grounds and filters, shredded dry leaves, grass clippings, and small twigs. I also add untreated paper and cardboard to the pile after tearing them up into small pieces.

Sawdust makes for a surprisingly good addition to my compost pile. It binds nitrogen into the compost as it decomposes. I bring bags to the lumberyard and sweep up their leavings. They’re happy to see the mess go.

The C:N Ratio

A good carbon and nitrogen mix is needed in the compost pile for decomposition to occur steadily. Scientists call this the C: N ratio. The best ratio is estimated to be from 24:1 to 30:1, with 2/3rds of the carbon generating energy and 1/3rd serving as maintenance of the pile.

The nitrogen keeps the compost pile from getting too moist. It also accelerates the rate at which materials break down. After the compost turns to humus, the nitrogen works as a superb fertilizer for gardens.

Think of carbon as brown material and nitrogen as green material.

If you need carbon in your pile, include corn stalks. Add some shredded old leaves and paper.

Materials with nitrogen include various plants, such as stems, vegetables, fruits, pine needles, and grass clippings.

Why is it Good to Compost?

Gardeners use compost to improve their soil’s structure. To increase the soil’s aeration. Good soil will have numerous air pockets to promote plant growth. To increase the soil’s capacity to hold water and nutrients.

Composting is environmentally friendly. If we composted most of the food we throw away, we could divert much of what goes into landfills.

Simple Recipes for Compost

Here are two recipes for what to add to a compost pile. I’ve had success with both:

4 parts fruit and veggie scraps

2 parts chicken or cow manure

1 part shredded newspaper (no colorful inks, please)

1 part shredded dry leaves

2 parts grass clippings

1 part chicken manure

1 part shredded leaves

How Do You Build and Layer a Compost Pile?

Picture of a pile of a composting organic waste

Composting Bins

Composting bins are available at almost any gardening store. Or, you can save money by building one out of wire fencing, cement blocks, bricks, or scrap lumber. A small, enclosed bin will take up little room.

Build a free-standing bin in a shaded corner away from the neighbors for those with larger yards, preferably near the garden. Make sure the area has good drainage. Leave one side open for turning the compost.

Layering the Compost Bin

To aerate the pile, layer wood chips or shredded newspaper so air can flow through. Fancy layers have been placed by creative composters over pipes delivering air in and out of the pile. High-tech piles include air blowers activated by a timer or sensors.

Layer coarse plant material, such as branches and twigs, on the bottom to allow oxygen to circulate upwards. Layer 6 to 10 inches of finer plant material such as leaves, grass clippings, and kitchen scraps on top.

Arrange 1 inch of soil or manure on top of the fine layer. This layer will provide needed microbes and nitrogen to the pile.

Repeat coarse layering material, fine material, and soil or manure until the pile is 5 feet tall after settling. A pile must be at least four cubic feet to provide enough food and a stable environment for the microbes.

The Three-Bin System

Try using three bins instead of one. One will serve as the home for finished compost, providing healthy humus for the garden when needed. Another will be made up of ripening compost. The third will be for new compost.

Happy is the gardener who never runs out of humus. I know.

I have a video on how to make compost. You can watch it below.

How Do Compost Piles Work?

Compost Decomposition

For decomposition to occur, five elements and conditions are essential: Carbon, nitrogen, air, water, and aerobic microbes.

Given the first four, the microbes will break down the organic material and generate heat. It’ll take about a week for the process to begin. The heat will hasten decomposition and destroy unwanted material, such as weed seeds, insect eggs, disease bacteria, and viruses.

Compost Maintenance

To get a reading of how the pile is doing, wait at least two days after assembling it, then pull away some of the surface material. Six inches down, the pile should be noticeably warm, if not downright hot. Use a compost thermometer. If it reads 130 degrees F, that’s perfect. If it drops to 100 degrees F, turn the pile. Check the pile each day, covering the hole after each test.

Sniff the compost. Good decomposing compost will smell like rich soil. Bad smells show there’s a problem with too much water, insufficient aeration, or a poor C: N ratio. Fix whatever is ailing your compost pile. Test the results. If it doesn’t work, try a different solution.

Moisture Content

Microbes in a compost pile need enough moisture to survive. Water serves as a transport for microbes and nutrients.

I make sure the pile is not too dry or too wet by checking the top foot weekly. I want it to be slightly damp. A dry compost will inhibit microbe growth. An overly damp compost will clog air passages, encouraging anaerobic microbes to grow. They will turn the pile into a putrid mess.

Check to see if recent rainfall has made the pile soggy. If it did, add dry, fine carbon material to sop up the water. Turn the compost with a pitchfork. Cover the pile if a rainstorm is coming.

What is the Difference Between Soil and Humus?

Humus is broken-down compost. It’s considered finished when it resembles rich soil, ready for the garden. Soil is part humus and part inorganic materials, including sand, clay, and silt. Soil also has some water and air in it.

In nature, decomposition turns organics into humus. Whether naturally formed or generated by human-constructed compost piles, humus serves as a fertilizer, adding rich nutrients to the soil.

How Can You Tell When Compost Has Turned to Humus and is Ready to Use?

When it looks like rich topsoil, dark, moist, and crumbly.

Use your nose.

Put a handful of the compost into a sealed plastic bag. In three days, if you open the bag and it smells sour, it’s not done yet. If it smells earthy, like dirt, then your compost is finished and ready for the garden. Start layering it on top of your garden bed, roughly around two inches deep.

Please don’t mix it with the soil. Let the nutrients seep in where the roots can get at them.

This is the most enjoyable day for me as an organic gardener. The day I see all my plants poking out through all that richness.

Conclusion

Make composting a habit. In this manner, you will protect the environment by reducing waste while also enriching your garden with necessary nutrients.

The time it takes to get excellent compost for your garden depends on various factors, including the materials you add to the pile and its size.

Furthermore, the speed of the process will be influenced by your efforts. Turning the pile regularly helps your compost decompose more quickly and efficiently.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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