Active Composting vs Passive Composting – What is the Difference?

The herbs and vegetables in your garden don’t need a commercially-produced fertilizer to be happy and healthy. However, not giving your plants any nutritional support is asking for trouble. Both active and passive composting can be used to enrich your soil but what’s the difference between them?

The method you use should be suited to your personality and availability.

Some gardeners have everything scheduled to a tee. They even know exactly how much orange peel they’ll have at the end of a week, so they can consistently work towards producing the black gold that their plants love.

Others also want the best for their plants but like to toss in cabbage, grass clippings or any other nutrient-rich material that they find, knowing that the bacteria might eventually do their job and contribute to the cycle of life. They’re glad to reduce the waste they pack in landfills but are less rigid with their composting schedule.

Both active and passive composting free up nutrients so that your plants can use them. The main difference between the two is the length of time that it takes to produce what you want. The effort that fans of active composting put in, allows organic matter to break down quickly. Gardeners who use passive composting find that it takes longer but they don’t need to spend as much time on management.

Sometimes you may switch from one style of composting to another out of necessity.

For example, if you have a new baby on the way, you might not have time to stick to your regular composting schedule. You’ll probably switch to passive composting amid the flurry of antenatal visits, setting up a nursery and everything else that comes with preparing for the birth.

Similarly, if you’re preparing to plant tomatoes or parsley in three months or so, you may switch to active composting, so you can have organic material ready in time.

Want to learn more about each composting method? Keep reading to learn more about their benefits and the ingredients you’ll need to be successful with the method you choose.

What’s active composting all about?

Gardeners who use active composting put effort into building and maintaining a compost pile. They may have watched instructional videos or read material on active composting where they learn to build layers and explains the role that decomposers play in the process.

They may even have a schedule for turning the pile. Each time the pile is turned, the microbial population goes through the cycle of growing, reproducing and dying. This is part of the reason why the vegetable matter in these piles is able to break down more quickly than those built by passive gardeners.

Remember, by turning your compost pile, you get the right blend of air and water and distribute moisture evenly. You’ll also increase the temperature enough to kill pests and weed seeds. Mixing the materials in your pile by turning allows them to decompose, so active gardening produces a finished product more quickly.

Ingredients Used in Active Composting

The ingredients used in active gardening are carefully planned to give gardeners the best results. You’ll need to start with the right ratio of carbon to nitrogen if you want to make sure the microbial population goes through the cycle with each turn.

Generally, this ratio, by content, is 25 parts of carbon to one part nitrogen. Typically, green, fresh material is higher in nitrogen than woody material. This means wood chips will have less nitrogen than cabbage leaves.

The 25:1 ratio is hard to achieve, so most active gardeners go for a ratio of two parts carbon to one part nitrogen, by volume. Active gardeners think of brown ingredients as being good sources of carbon and green ingredients as being good sources of nitrogen. This is why their passive composting friends may see them monitoring the amount of brown and green they have in their pile.

Temperature of Active Compost Piles

The temperature of a pile produced via active gardening usually fluctuates.

It reaches high temperatures that kill off weed seeds and then, this temperature slowly drops as the bacteria in the pile start to die off. Active bacteria produce the high temperatures but as they work to break down the nitrogen to obtain energy, their food source diminishes, so eventually start to die off. 

This temperature cycling only occurs in active compost piles. Passive gardeners do not tend to keep their piles wet as diligently as active gardeners and the bacteria need moisture to thrive. There are bacteria in passive compost piles but they are fewer in numbers.

You could think of it almost like a factory. In an active pile, there are a lot of workers moving around, stopping by the water cooler and generating heat. In an active pile, less heat is generated because there are less workers moving around. Less workers also means less work is done, which is why passive piles take longer to break down.

Speed of Decomposition

An active compost pile will usually break down within four months. This makes this composting technique ideal for gardeners who are always putting in new seedlings and rotating crops, so they constantly need fresh black gold. 

On the other hand, in a dry environment, it can take years for a passive compost pile to break down completely.

In the tropics or another humid environment, a passive pile will break down in a few months. The content of passive compost piles produced in dry environments is lower in quality because it’s been exposed to the elements for a longer time.

With an active pile, you’ll get nutrient-dense compost that doesn’t have a heavy texture. There’s less leaching of nutrients due to rain, wind and other factors. 

What is Passive Composting?

Passive gardening is often used by people who know they don’t have time to turn a compost pile on a regular basis. However, they do not want to send perfectly good kitchen scraps to a landfill to take up space. They have a garden but do not need to have a compost pile working rapidly to deliver perfect compost.

What they do need, is a place where they can slowly convert the leaves that they rake up in the spring. When they mow their lawn, the clippings go there. They may not even bother with chopping up egg shells, bolted lettuce or bits of carrot to speed up decomposition because they really don’t have the time and they know it.

Passive composters know that they can still get beautiful dirt from their pile. They give up on angst and embrace environmentally-friendly living, without the stress. Some only have containers to plant in but they have one bucket that’s just for passive composting. It works and their potted plants get all the black gold that they need.

Passive Composting Ingredients

The ingredients in passive composting are the same as those used in active composting.

However, the ratio of nitrogen to carbon is more flexible. You’re likely to find everything from sticks and twigs to broccoli in these piles. Since the carbon content is often high, these piles tend to look bulky.

Passive composting piles are good for building up clay soils. It loosens clay soils and that makes it easier for each plant’s roots to penetrate the soil. As you probably know, some plant roots have a tough time with clay soils, especially when the soil is dry and tough.

Passive compost piles are good for mulching. You can apply it directly to the soil surface around your fruit trees. It will prevent water loss so you retain it. It won’t burn or shock your plants and they will constantly have nutrients being released into the soil.

Passive Composting Temperature

Passive compost piles don’t have the extreme fluctuations in temperature that are observed with active piles. These piles are usually drier so the bacteria don’t thrive as much as they would in an active setting. This prevents the piles from reaching the high temperature spikes observed when the bacterial population is at its peak.

Also, did you know there’s an ideal temperature for decomposition?

Just like humans get sluggish in really cold weather, bacteria get sluggish when the temperature drops. The optimal temperature for decomposition is 135 degrees Fahrenheit and the breakdown of organic matter increases as the temperature rises, to a point.

You don’t really want to go beyond 160 degrees Fahrenheit. If your compost pile is kept relatively warm, you’ll have more activity going on than when it’s kept cool.

A compost pile can go from active to passive. For example, suppose you stop paying attention to your pile for a while because you’re busy at work or are coaching your children’s sports team. You lack the time to wet and turn the pile.

If the pile isn’t damp enough, bacteria won’t thrive in it. Your pile will become passive. If you want your pile to start breaking down actively again, you can turn it and wet it. You should see the internal temperature start to rise as microbial activity increases.

You could touch a compost pile with your hand and figure out whether it’s likely to be active or passive. Active piles actually feel hot to the touch, while a passive pile will feel fairly cool. When you think of hotbed activity, that’s an active pile, bursting with rapid chemical reactions such as those involved in the digestion of organic matter to release organic acids. 

Water Content of Passive Compost

Passive compost tends to be dry, unless you’re fortunate enough to be receive frequent rainfall. That way, your compost pile will keep wet enough to encourage microbial activity, even if you don’t have time to water the pile regularly. 

Temperature and moisture both work together to affect the rate of decomposition. This means that if your pile is fairly damp, but you live in a cool area, it won’t break down as quickly as if it had the same water content but you lived in a warmer area.

Passive gardeners who live in cold, dry areas have to wait the longest to get black gold. The temperature is not ideal for decomposition and the pile isn’t getting wet often enough for bacteria to enjoy living and working it it. 

Dense passive piles that contain small ingredients will retain moisture better than loosely packed piles that consist of large materials like tree branches. if you’re a passive composter, your pile will break down more quickly if you take a few minutes to chop branches into smaller pieces first.

What kind of product will you get from passive compost piles?

The compost that you’ll produce with a passive pile will look different from that obtained with active piles. It usually looks heavier or denser than that from an active pile. You may even still be able to recognize a bit of twig or some other plant material.

This is because the pile wasn’t turned. The bacteria couldn’t get to the material and break it down sufficiently. The plant material that’s left undigested will slowly break down later on. However, you’ll not have nitrogen available from it during that time.

Active composting vs passive composting – which is better?

if you have clay soil, passive composting will help you to keep your soil porous and improve its texture. It also helps your soil with nitrogen and won’t cause a deficiency in that nutrient.

If you need mulch, passive composting is ideal for that. It helps the soil to retain water, so you can conserve water use in areas where you use wells for watering. 

If you produce an array of crops and need compost regularly, active composting helps you to produce black gold on time, in a predictable way. It takes more effort than passive omposting but the quality of the compost is higher.

I hope this helped to clear up any questions that you had about the difference between passive and active gardening. Your garden doesn’t need fertilizers that don’t complement your lifestyle choices. You can have a healthy, organic garden by using a composting method that complements your style. Gardening is about joy, not guilt, so choose the technique that suits you best.