Skip to Content

What’s the Difference Between Soil and Compost? (And When to Use Each)

What’s the Difference Between Soil and Compost? (And When to Use Each)

Share this post:

Disclaimer: Some links found on this page might be affiliate links. If you click an affiliate link and make a purchase, I might earn a commission. As an Amazon Associate I earn from qualifying purchases.

Although some people use the terms soil and compost interchangeably, there is actually a big difference between them.

They each have important functions in gardening, but soil is a natural product that is formed in the environment, and compost is recycled plant and kitchen waste. They complement each other, but they are not the same thing.

What Is Soil?

Plants grow in soil, which means that soil has a critical role on the planet. Because plants are able to harvest energy from the sun and transfer it up the food chain, plants are essentially responsible for all life. This means that soil is critical for the survival of life on earth.

So, what exactly is soil? It is the top layer of dirt on the earth. It is composed of sand, silt, minerals, organic matter, liquids, and gases.

Close Up Of Soil

It provides the structural support for plants, as well as water and nutrients. It is black or dark brown in color, and there are many different kinds of soils in different geographical locations.

There are three types of soil, which include sand, silt, and clay. Sand is made of small particles of weathered rock. It drains well because it is coarse and loose.

Sand is not very good for growing plants because it doesn’t hold the water or nutrients that they need.

Silt is finer than sand, and it holds water better. The third type, clay, is fine grained, and there is very little space between the particles for air or water. As a result, it is not great for growing plants.

The soil that is best for growing plants is loam, which is a combination of sand, silt, and clay. The makeup varies depending on how much of each it is composed of, but this is the soil used to grow plants. It holds moisture and nutrients, but it also has the ability to drain, which makes it ideal for the growth of plants.

In addition to the inorganic materials, soil has various organic matter and gases inside it. The organic matter is decaying plants, insects, animals, and fungi, and as decomposers break this matter down, they return the nutrients and carbon to the soil.

Oxygen also goes through the soil, and earthworms and other organisms help to keep it going.

Soil forms as a result of the interactions of these materials, and it forms over a great deal of time, nearly 1000 years. There is soil over most of the earth’s surface, and you can buy it as well. Soil is where you plant your plants, and it is where they grow.

What Is Compost?

Compost Bin

Compost is made from dead plants and kitchen waste. It is completely a product of these items. It can include plants that are dead or branches, as well as any other living thing that dies.

Decomposers play an important role in breaking down these dead organisms and returning their nutrients and gases to the earth to fertilize new plants.

Compost is used to help plants grow. It is an amazing fertilizer because it is so rich in nutrients. Besides the differences of which each is made of, soil basically is where plants grow, and compost is used as a fertilizer.

The Benefits of Soil and Compost

The benefits of soil are self-explanatory when you understand what it is. It is ultimately responsible for life on earth.

Because soil has the ability to provide the structure to support plants, and it drains and allows the transport of nutrients and water to plants, it is critical for their survival.

When you are planting in your garden, you will use soil in your beds, baskets, pots, or in the ground to plant your plants. Having good soil that is full of nutrients is so important and offers the following benefits:

  • Helps to cycle nutrients for plants, including nitrogen, phosphorous, potassium, calcium, magnesium, sulfur
  • Reduces pest problems
  • Helps clean the environment by decreasing air pollution
  • Provides base for plants to grow
  • Drains well so that plants don’t drown
  • Allows transport of water to plants

Compost is also beneficial. The life cycle begins with plants, and it comes full circle to the decomposition of dead organisms and their return to the earth.

Breakdown Of Compost

Decomposers, such as fungi, break down dead organisms and kitchen waste, and their nutrients are returned to the earth.

Compost is nutrient dense, and it is an incredible fertilizer, especially in situations where the soil has been overused and depleted of its nutrients. Soil that has been overused has a hard time sustaining plant and crop growth, and compost becomes almost essential for the cycle to continue.

Compost also can improve the structure of soil because it loosens heavier soils by adding organic matter. It binds with water and improves the absorption and flow of water in the soil as well, and it protects the surface soil from environmental damage.

Compost helps soil to hold more nutrients for plants, and it acts as a buffer against sudden or quick changes to the composition of the soil.

The Drawbacks of Soil and Compost

Because soil is technically the top six inches of the earth’s layers, it comes in many shapes and forms. Loam is a combination of silt, sand, and clay, and it is ideal for plant growth.

However, individually, each type of soil has its own set of drawbacks.

Layers Of Soil

Sand: Sand is fine and loosely packed, and as a result it is difficult for plants to grow in sand. They have trouble taking root and the sand doesn’t support their structure. It also drains too well, so it doesn’t transport essential nutrients and water to plants.

Silt: Silt is fine, but is able to hold water, so it has a better chance of allowing plants to grow.

Clay: Clay is densely packed with fine particles, and it is very difficult for plants to grow. There isn’t enough space between the particles for water and oxygen to circulate, which plants rely on for photosynthesis.

For this reason, loam is the best kind of soil, and it is a combination of the three types. It varies in different geographic locations, and it is what allows plants to grow.

Compost has its benefits, but it has drawbacks as well. It requires a large space away from populated areas because the odor is strong as the organic materials decompose.

In addition, compost piles can be dangerous because pathogens can breed there, which is a threat to people who may be interacting with the compost pile.

Also, people must take care because decomposition involves all kinds of chemical reactions, and you need to be aware of what is in your compost pile.

When to Use Soil vs. Compost

Planting A Small Tree

If you are planting a garden, it is important to understand the differences between these two materials, their benefits, and their drawbacks. In addition, you need to understand when to use each of them.

You should always use soil for planting your plants. You never plant in compost. Soil is the medium that holds plants in place and provides them with nutrients and water. You cannot plant in compost, as it is recycled dead and dying organic matter.

Compost is used as a fertilizer and a soil conditioner. It can be spread along the surface of the soil, or it can be mixed down into it. When you add compost to your soil, it helps the soil to hold air and water, and it drains better.

In addition, soil that is treated with compost has fewer pest and disease problems. This is a huge benefit. Because compost contains beneficial soil microorganisms, it allows them to control harmful microorganisms.

Compost will always continue to decompose because it is dead organic matter, and it decomposes until it is gone. Some climates cause it to decompose more quickly, which means you will use more of it in your garden.

Although you should use it all year round, some people suggest that it is especially helpful in the late fall because it helps to protect the soil organisms, and they actually spend the winter working this compost into the soil.

Final Thoughts

Many people use the words soil and compost interchangeably, but the two are very different and should be used accordingly.

Although compost is beneficial to soil, it is a helper, whereas soil is the main show. Soil is necessary for the survival of life on earth, as nothing would live without plants.

To sum it up, you will plant in your soil, as it holds the nutrients and water necessary for plant survival. You will use your compost to fertilize your soil and help it to be as healthy as possible.

You can use compost to improve your soil quality if you have overused the soil, and if you cover it with compost in the late fall, the organisms in the soil will break it down all winter so that it is ready to provide nutrients to the earth and your plants in the spring.

Share this post:

Irene Floyd

Thursday 8th of June 2023

Thank you for a very informative article, but there is one item on which we disagree. You state that a compost pile is smelly but that is only true if it contains the wrong ingredients, such as meat or fish. I have 5 compost bins in my suburban yard and they never smell bad. I layer green stuff (vegetable scraps, fresh weeds) between brown stuff (dead leaves and weeds, wood chips, spent tea and coffee grounds) and also throw in some crushed egg shells when I have them. In a matter of months, it becomes a very fine compost, ready to use.


Friday 29th of April 2022

Actually, you can plant straight into compost after it has matured.