Compost vs. Humus — What's the Difference?
By Tayyaba Rehman — Updated on November 2, 2023
Compost is decomposed organic matter used as fertilizer; humus is the final, stable result of decomposed material enriching the soil.
Difference Between Compost and Humus
Table of Contents
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Key Differences
Compost is an assortment of decomposing organic matter like food scraps and yard waste, while humus is what remains after compost has fully broken down. Compost is an active process, involving the breakdown of organic materials over time. Humus, on the other hand, refers to the final, stable byproduct of this composting process, which becomes part of the soil.
The transformation from compost to humus involves a complex process of microbial and fungal breakdown that releases nutrients slowly into the soil. Compost can be considered a stage in the life cycle of organic matter, on its way to becoming humus. While compost enriches the soil, humus fundamentally changes its composition, improving its structure and fertility.
While compost is often rich in nutrients and used to feed plants, humus serves as a conditioner for the soil, improving its physical properties. Compost is added to soil to help plants grow, but humus is already integrated within the soil, aiding in water retention and providing a habitat for beneficial microorganisms.
Compost is known for its ability to be produced and utilized in gardening relatively quickly, with a recognizable origin of materials. Humus, meanwhile, represents a long-term accumulation in the soil, sometimes taking years to fully form and often unidentifiable in terms of its original components.
A key difference lies in appearance and texture: compost varies based on its ingredients and stage of decomposition but generally resembles the organic materials it's made from. Humus is dark, rich, and uniform in texture, indicating its complete decomposition and integration into the soil.
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Comparison Chart
Definition
Decomposed organic material for fertilizing.
Stable, final product of decomposition in soil.
Stage of Decomposition
Intermediate; active decomposition.
Final; fully decomposed.
Nutrient Release
Faster and can be rich in nutrients.
Slower, more stable nutrient release.
Role in Soil
Adds nutrients, used as a soil amendment.
Improves soil structure and fertility.
Physical Characteristics
Varied texture, may have recognizable pieces.
Dark, spongy, uniform texture.
Compare with Definitions
Compost
A mix of organic materials designed to decompose.
We added compost to the garden to improve plant growth.
Humus
Organic component of soil formed by decomposition.
The soil's richness was due to its high humus content.
Compost
The result of a controlled process that breaks down organic matter.
The compost pile generated heat as it broke down.
Humus
A mature compost that has undergone full decomposition.
Humus is vital for maintaining soil health.
Compost
A heap where garden and kitchen waste is composted.
He built a compost bin to reduce waste.
Humus
Stable organic matter that helps soil retain moisture.
Adding humus improved the water retention of the soil.
Compost
Compost is a mixture of ingredients used to fertilize and improve the soil. It is commonly prepared by decomposing plant and food waste and recycling organic materials.
Humus
The dark, organic material in soil from decomposed plant matter.
You can find worms thriving in the humus layer.
Compost
A mixture of organic matter, as from leaves and manure, that has decayed or has been digested by organisms, used to improve soil structure and provide nutrients.
Humus
In soil science, humus (derived in 1790–1800 from the Latin humus for 'earth, ground') denominates the fraction of soil organic matter that is amorphous and without the "cellular cake structure characteristic of plants, micro-organisms or animals". Humus significantly affects the bulk density of soil and contributes to its retention of moisture and nutrients.
Compost
To convert (vegetable matter) to compost.
Humus
A brown or black organic substance consisting of partially or wholly decayed vegetable or animal matter that provides nutrients for plants and increases the ability of soil to retain water.
Compost
To fertilize with compost.
Humus
Variant of hummus.
Compost
The decayed remains of organic matter that has rotted into a natural fertilizer.
Dig plenty of compost into clay or sandy soil to improve its structure.
Humus
A smooth thick mixture of mashed chickpeas, tahini, oil, lemon juice, and garlic, used especially as a dip for pita.
Compost
(UK) A medium in which one can cultivate plants.
Once the seed tray is filled with compost, insert the seeds spaced 3 cm apart from one another.
Humus
A large group of natural organic compounds, found in the soil, formed from the chemical and biological decomposition of plant and animal residues and from the synthetic activity of microorganisms.
Compost
(obsolete) A mixture; a compound.
Humus
Alternative spelling of hummus
Compost
To produce compost, let organic matter decay into fertilizer.
If you compost your grass clippings, you can improve your soil.
Humus
That portion of the soil formed by the decomposition of animal or vegetable matter. It is a valuable constituent of soils.
Compost
A mixture; a compound.
A sad compost of more bitter than sweet.
Humus
Partially decomposed organic matter; the organic component of soil
Compost
A mixture for fertilizing land; esp., a composition of various substances (as muck, mold, lime, and stable manure) thoroughly mingled and decomposed, as in a compost heap.
And do not spread the compost on the weedsTo make them ranker.
Humus
A thick spread made from mashed chickpeas, tahini, lemon juice and garlic; used especially as a dip for pita; originated in the Middle East
Compost
To manure with compost.
Humus
A natural conditioner for soil fertility.
Farmers value humus for its ability to improve soil structure.
Compost
To mingle, as different fertilizing substances, in a mass where they will decompose and form into a compost.
Compost
A mixture of decaying vegetation and manure; used as a fertilizer
Compost
Convert to compost;
Compost organic debris
Compost
A natural fertilizer made from decayed organic matter.
Compost enriches the soil with vital nutrients.
Compost
Material used in composting to return nutrients to the soil.
She turned the compost to speed up decomposition.
Common Curiosities
How does compost turn into humus?
Compost turns into humus through microbial and fungal breakdown over time.
What is compost made of?
Compost is made of decomposing organic matter like food scraps, leaves, and manure.
Is humus the same as compost?
No, humus is the end result of compost once fully decomposed.
Why is humus important for soil?
Humus is important for improving soil health, fertility, and water retention.
What is humus?
Humus is the stable, nutrient-rich organic material that results from fully decomposed compost.
How long does it take for compost to become humus?
It can take from several months to several years for compost to fully become humus.
How often should I add compost to my garden?
Compost should be added at least once a year or as needed by plants.
Can you buy humus?
Yes, humus can be bought from garden centers as a soil conditioner.
What does compost do for soil?
Compost adds nutrients and improves soil structure for better plant growth.
Can compost be harmful to plants?
If not properly decomposed, compost can be harmful; it should be mature before use.
What does humus look like?
Humus looks like dark, crumbly soil and has a spongy texture.
Does humus have a smell?
No, humus does not have a strong smell; it should smell like earth.
How do you identify humus in soil?
Humus is the dark, organic layer of soil that's rich and soft.
Can I make humus at home?
Yes, by composting over time, humus can form as the material fully decomposes.
Is there a difference in pH between compost and humus?
Yes, compost can vary in pH, while humus generally has a neutral pH and can help buffer soil acidity.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
