Among circles of gardeners, the terms “humus” and “compost” get used interchangeably.
While both humus and compost are essential to healthy land, they are different in many ways.
But, do not think that compost and humus are applied in totally different situations.
They are standard parts in both artificial gardens and natural greeneries.
It is essential that you know the difference between humus and compost if you are serious about gardening.
If you want soil that will provide nutrition to all types of plants over the different seasons, read this guide, and you will have a better understanding of how to use humus versus compost.
Table of Contents
- 1 Is Humus and Compost the Same Thing?
- 2 What is Humus soil?
- 3 What is Compost?
- 4 How to Tell Difference Between Humus and Compost
- 5 When & Why to Add Humus or Compost to Soil?
- 6 Conclusion
- 7 References
Is Humus and Compost the Same Thing?
No, the difference between compost and humus is simple; humus is considered a naturally-formed compost, whereas compost is man-made organic matter that is already decomposing, usually from food waste.
What is Humus soil?
Since humus is naturally made, it could be rotting twigs under the water in swamplands or piles of leaves buried in the soil in forests.
Humus is effectively found everywhere, as it is a natural process that is always producing ecosystems.
Any garden soil has humus since the soil you dig up in your yard has been in the decomposition cycle for years.
What is Compost?
Compost is a group of organic matter that is already decomposing.
The definition is not strict on the amount of soil, amount of organic waste, or storage.
Related post: How to Make Your Own Compost
As long as it is rotting in the soil, it is considered composted.
You can usually find compost bins in houses.
They look like open containers with a bed of soil topped with organic waste from the house.
This waste could be leftover food, fruit peels, or even paper.
It is hard to know whether it has finished composting.
A good rule is if the waste you have thrown there is “not there” anymore, it means it has already decayed with the soil.
Related post: How Much Compost Do You Really Need?
Finished compost is usually used in businesses that involve keeping plants and trees healthy.
Some good examples are nurseries, hotels, and resorts.
However, a lot of homeowners are now making compost bins for their plants.
How to Tell Difference Between Humus and Compost
Here are some ways in which compost and humus are different from each other.
Level of decay
Compost is traditionally any organic matter that has begun to rot. However, it has been attached to a different definition to separate it from humus.
Compost is any pile that is still decaying. When a compost has become “stable,” it is now considered humus.
To sum it up, when a leaf is still decaying, it is composted.
When a leaf has “blended” into the soil, it is now humus.
Appearance and texture
Compost is, well, soil that has rotting banana peel or scrap meat. It is heterogenous that you can distinguish which materials are which.
Humus looks darker and feels more like a wet sponge than the topsoil, which has a brown and grainy texture.
The reason for this is humus has almost zero exposure to humans and animals when untouched.
The decomposition process is uninterrupted.
Part of the reason why the term “compost” is used more often among gardeners is that compost has human involvement in its decomposition compared to humus which has none (direct, a least).
Compost bins are continually fed with organic waste from human households.
The formation of humus is often unseen.
Think of the pile of leaves at the nearby park. Park rangers do not assemble these piles of leaves every day.
It just forms there, and the next time you visit, you will notice that it is gone and fresher leaves have replaced it.
Method of decay
To understand how different compost and humus are in both decays, we need to know how humans intervene.
The reason for this is compost decays with oxygen presence.
This is known as aerobic decomposition. This is possible because man-made bins have aeration holes or are just plainly open.
Meanwhile, humus is usually made via anaerobic decomposition or decaying without (or minimal) oxygen.
Humus has higher levels of NPK or Nitrogen, Potassium, and Magnesium since the organic matter has wholly decayed.
However, since the anaerobic process is like fermentation, humus has more carbon and methane.
Macro-Nutrients and Micronutrients in Soil
Here is a handy list of the macro-nutrients and micronutrients found in soil.
- Nitrogen. It is helpful in the vigorous growth of plants, especially in spreading plants.
- Potassium. Aids in the reproductive function of plants.
- Magnesium. Helps in keeping the plant looking green and healthy.
- Calcium. Important in having a permeable wall in which nutrients come in.
- Phosphorous. Necessary in root and seed growth.
- Sulfur. Maintains a healthy metabolism.
- Iron. Also helps in chlorophyll-related functions like oxidation.
- Manganese. Essential in photosynthesis, nitrogen metabolism, and respiration.
- Zinc. Responsible for synthesizing proteins.
- Copper. Activates enzymes for photosynthesis and respiration.
To put it side-by-side, compost is any decaying matter. Whether it is a dead bird or a leftover apple, it is compost.
It becomes humus when it has wholly decayed, absorbed nutrients by the soil, and becomes part of the soil.
You can say that everything is compost first, then humus, but not the other way around.
When & Why to Add Humus or Compost to Soil?
Compost is used to have an eco-friendly way of disposing of organic waste.
Instead of putting it in a plastic bag and throwing it along with other non-biodegradable waste, you can simply throw it to any land near you (as long as you do this in a tidy manner).
Also, it is a way of keeping any organic waste from being thrown in the drain and entering the wastewater system.
Once the organic waste reaches a river or lake, it can cause algae growth, which takes up the oxygen for the fish.
You should also use your compost when planting or transplanting seedlings.
The seedling will have healthy soil to start growing since the first few weeks (especially after being transplanted to the soil from a pot) are vital in the survival of the seedling.
benefits of humus Over compost
Humus is naturally richer in nutrients due to its longer duration of decomposition.
Humus is an excellent way to start your compost.
You can find the humus when you dig deep enough to reach a moist and spongy layer of soil.
Usually, once you see earthworms, it is the humus layer already.
Mixing it with compost will make the decomposition process faster.
Make sure you include some worms in your compost bin.
Humus is a preferable choice when it comes to enriching semi-adult or even fully mature trees.
This is because as trees grow, they require more nutrients to live.
When a tree is fully grown, the leaves will naturally fall, become compost when decaying, then become humus when fully decayed.
Adding Humus or Compost to keep soil healthy
While most gardeners encourage to add the latest batch of fertilizer from the local market or establish a strict watering schedule.
The most effective way of keeping your garden healthy is by letting it be.
This does not mean that you will have zero attendance towards your garden.
This means you do not need to keep adding store-bought garden supplements or gadgets to have a healthy garden.
Your goal is to help plants have healthy growth by themselves and not tamper with it.
Plants have been growing, dying, and reproducing since the start of time, so they know how to adapt and survive in natural conditions.
This is the reason why tropical rainforests are lush and dense compared to nearby forests in urban areas.
For the sake of argument (how to keep your garden healthy), one discreet way of doing this is to have a compost bin and keep your garden from your unruly pets and from being walked on.
Not knowing the difference between compost and humus is going to make you a lousy gardener.
Many gardens have thrived, even if their owner is not an expert in the technical know-how of compost and humus.
However, knowing the difference is an advantage.
You should know how the soil interacts with organic matter and how it is beneficial to your plants (and to the soil itself).
If you’re looking for alternative growing mediums, check out peat moss or coco coir.
Plants are self-maintaining but delicate beings.
While it is best for them to have a minimal routine, they are also vulnerable to death caused by bad practices.
Some of us do not want to be good gardeners, but great ones instead.
Lindsey Hyland grew up in Arizona where she studied at the University of Arizona’s Controlled Environment Agriculture Center. She continued her gardening education by working on organic farms in both rural and urban settings. She started UrbanOrganicYield.com to share gardening tips and tactics. She’s happy to talk about succulents and houseplants or vegetables and herbs – or just about anything in a backyard garden or hydroponics garden.