What Happens if You Don’t Turn and Aerate Compost

Composting requires greens for nitrogen and browns for carbon in the feedstock, broken down by bacteria into compost. In order to do so, these bacteria need air and water like any other living organism.

If you don’t turn and aerate your compost, the following could happen:

  1. Your compost gets a slower process of decomposition.
  2. Your compost pile starts to clump and becomes more compact.
  3. Your pile will get an uneven decomposition.
  4. There will be excess or insufficient moisture in your compost pile.
  5. The compost will release bad smells.
  6. Your compost may experience overheating.
  7. Your compost will have a more acidic pH value.
  8. Pests will start colonizing your compost.

In this article, I’ll explore the problems caused by not turning and aerating your pile and tell you how often you should aerate your compost. I’ll also explore how you can compost without turning, so read on!

Issues Caused by Not Turning and Aerating Compost

Not turning and aerating compost can cause issues in your pile regardless of whether you’re using a composting bin or not

Air is essential to the microbes that break down the composting feedstock. Turning your pile is one of the best ways to replace the oxygen used up by the microbes as they work on decomposition. Overall, directly aerating your compost affects the quality of your compost and how quickly it is processed. 

As discussed below, you might notice some problems in your pile if you don’t turn and aerate your compost:

Your Compost Gets a Slower Process of Decomposition

Most home and garden composting rely on aerobic decomposition, which is the decomposition of the organic matter in your feedstock using bacteria that need oxygen. 

Oxygen allows the bacteria to thrive and multiply, and the larger numbers of bacteria allow them to decompose faster. Aerobic decomposition is ideal for home composters, as the byproducts are heat, water, and carbon dioxide. 

When you don’t turn and aerate your compost, there is no way that fresh air is being introduced to the pile. This prevents the bacteria from multiplying, which limits the speed of decomposition.

Over time, as the existing bacteria use up all the available oxygen in your pile, they’ll start dying off, slowing the process further. Eventually, your pile might also settle into anaerobic decomposition caused by bacteria that don’t need oxygen. 

Anaerobic decomposition is not ideal for home composters, as the process results in byproducts like methane, which takes longer, and the final product is not sterile as it would be after aerobic decomposition. 

Your Compost Pile Starts to Clump and Becomes More Compact

Sometimes, your greens might clump together when you add them to your compost pile. This clumping may be a result of texture or the distribution of air and microbes through your compost pile. 

This is especially true for grass clippings, which tend to stick together in clumps and decompose that way, creating a congealed mass that blocks airflow. 

Turning your pile is a way of addressing any potential compacting and clumping because of the process of turning breaks up any clumps of feedstock. It also incorporates air into the pile, making it fluffy and less likely to stick back to itself.  

When you don’t turn your compost regularly, your pile will likely become more compact, reducing the airflow through the pile and affecting the decomposition process. 

Your Pile Will Get an Uneven Decomposition

Turning and aerating the pile is important to move the composting feedstock around within itself, allowing any hot or cold spots to intermingle and making the mixture more homogenous

When you’re not turning and aerating your compost pile, possible clumping, large air pockets, the presence of white worms, and other pests may all contribute to uneven decomposition.

In places where the greens have clumped together, the airflow will become low, and the number of microbes will dwindle until the decomposition slows and cools down at once. The compost will likely become wet and soggy, inviting pests like fruit flies to the pile. 

The compost might heat up too quickly in a space with large air pockets, burning through the nitrogen and leaving a white powder on your compost. This white powder is known as flash, as it is formed when nitrogen burns. 

The heat that can burn nitrogen is also too high for the bacteria—even the thermophilic bacteria that work on the compost in the second stage as it heats up. With all the bacteria burned off, the compost in that space will become dry, crumbly, and stagnate

There Will Be Excess or Insufficient Moisture in Your Compost Pile

You should keep your compost pile moist to support the activity of the microbes and accelerate the decomposition process. However, the compost should not be soggy or dripping with water. 

The ideal percentage of moisture for a compost pile is between 40 and 60%, as this will ensure that the microbes are hydrated but not drowning.  

Most water loss from your compost occurs through evaporation, especially in an open composting unit. However, in closed bins, the insulation helps prevent a great deal of water loss. 

If the drainage and aeration holes built into your bins are blocked, then it’s likely that your compost will get waterlogged, drowning the microbes and halting decomposition entirely.

On the other hand, dry places require moisture to be added to compost. Most people water their compost as they turn it, which allows them to distribute moisture evenly through the pile. 

If you don’t turn your pile, you won’t water it either, which will cause the pile to dry up, and the composting process will halt. 

The Compost Will Release Bad Smells

Bad odors are inevitable in decomposition, but healthy compost actually has very little odor. The browns in the compost cover the composting kitchen scraps and prevent odor from escaping.

What helps the process along is when the compost is turned regularly, allowing the air to circulate through the compost, dissipating the remaining odor.

Bad smells tend to attract bears and other scavengers like rodents, raccoons, and dogs and are a sign of poorly maintained compost. 

Turning and aerating the compost also dissipates bad smells by breaking up any large clumps of nitrogen and distributing the browns more evenly through the pile. 

Your Compost May Experience Overheating

Compost piles can reach up to 160 °F (71.11 °C) during the second stage of composting, which is the thermophilic stage. However, sometimes, a high percentage of nitrogen in a pile can cause temperatures to go higher, killing the microbes or forcing them to become dormant. 

While the heating up of the pile is necessary for hot composting, overheating can burn through the feedstock—burnt feedstock results in compost that doesn’t have the nutrition that makes it a good soil amender.  

Turning and aeration forces air into the pile, which helps cool overheated compost by accelerating heat loss from the pile and maintaining the heat at a level ideal for decomposition. 

Your Compost Will Have a More Acidic pH Value

Good compost is typically neutral to alkaline, with pH values ranging between 7 and 8. This pH value is a result of the speed of the decomposition process. When kitchen scraps and other food scraps decompose slowly, they produce organic acids that release a strong odor of ammonia and shift the pH value close to 5. 

The shift of the pH value of compost to something more acidic affects the quality of the compost and its effectiveness as a soil amender. When compost is properly turned and aerated, the process of decomposition is accelerated, which doesn’t give the nitrogen scraps enough time to produce any organic acids. 

Pests Will Start Colonizing Your Compost

Compost that’s turned and aerated regularly doesn’t allow pests to colonize the pile. Ants, white worms, fruit flies, and other creatures can help overall composting. However, their presence usually indicates that the compost is giving off an odor that is attracting them to your pile. 

Not only does turning and aeration dissipate any odors that might be emanating from your pile, but it also disturbs the eggs and nests of pests that might be making your compost pile their home. This deters the creatures from nesting and colonizing your compost. 

How Often Should You Aerate Your Compost?

Now that you know that aerating compost is essential, you may want to know how often compost needs to be aerated to keep it healthy and accelerate decomposition. 

You should aerate your compost once every 3 to 4 days in the first two stages, especially in the thermophilic stage when temperatures in your compost pile climb rapidly. Once your compost enters the cooling and maturation phase, you can turn it at least once a month or more frequently as necessary.

Compost needs more attention when it just starts breaking down, but after the thermophilic stage, the majority of the nitrogen would have broken down into humus already. The last stage of cooling and maturation is essential because you can’t use partially decomposed compost, but it doesn’t need as much attention. 

Can You Compost Without Turning?

Turning your compost is essential for aeration, but you’ll probably wonder if it’s possible for aerobic decomposition to happen without turning?

You can compost without turning. To do this, mix the compost with a compost aerator or poke holes in the pile with a stick to create air channels. Finally, the best way to maintain aeration is to incorporate twigs and sticks, and other browns that will create air pockets in the compost pile.

Large composting units sometimes use the static aerated pile method, where airflow in the compost pile is ensured through blowers or pipes running through the composting unit. 

Final Thoughts

Turning and aerating compost is essential. It’ll ensure a good quality compost at the end of the process that has decomposed quickly and evenly, without bad odors, pest infestations, acidic pH values, or burning through the feedstock.

You should turn and aerate your compost often in the beginning. Then, shift to turning it every month once it starts curing.

While you can compost without turning, you need to ensure aeration channels are set up for the decomposition to stay an aerobic process.

Alexander Picot

Alexander Picot is the founder of TheGrowingLeaf.com and its lead content writer. He created the website in 2022 as a resource for horticulture lovers and beginners alike, compiling all the gardening tips he discovered over the years. Alex has a passion for caring for plants, turning backyards into feel-good places, and sharing his knowledge with the rest of the world.

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