Soil Carbon: 10 Things (2024) You Should Know

One of the most important factors of soil is how much carbon it stores.

This is known as–drum roll please–soil carbon, and it’s not only a crucial factor that determines the health of the plants, but it also plays a role in managing the world’s CO2 levels.

As more and more countries are focusing their attention on reducing CO2 levels, soil–as they say–has officially entered the chat.

But not all soil works the same, and there are certain factors that determine how much it can store and how much it can sequester from the air.

Suddenly soil looks like more than just a pile of dirt, huh?

In this article, we’re going to dive into the topic of soil carbon and discuss good-to-know information, such as what it is, how it works, how it impacts the environment, and what factors decide soil’s ability to hold carbon.

As climate change becomes more of a pressing issue, it’s important to understand soil’s role in the fight to improve conditions!

1. What Is Soil Carbon? (Why Is it Important?)

Soil carbon refers to the carbon content stored in soil.

The forms of carbon in soil can be organic or inorganic.

But what’s the difference?

Organic carbon in soil is caused by plant and animal waste, microbes, and other organic matter. 

Inorganic carbon in soil refers to mineral forms of carbon, which are primarily derived from weathering parent material, such as when bedrock begins to dissolve and releases minerals and rocks containing carbon.

Carbon is a crucial element in soil.

It helps plants grow properly by regulating the nutrient cycle and keeping the soil texture and structure at the ideal levels.

Without the right carbon levels, it can lead to the deterioration of all the vegetation in an environment, which then has a ripple effect on all the animals that rely on those plants to live.

Additionally, soil is an important part of the Earth’s carbon cycle.

Because of its ability to sequester carbon dioxide, soil helps regulate greenhouse gases in the atmosphere.

When soil is damaged or not properly maintained, it’s unable to sequester as much, resulting in higher levels of CO2.

2. How Does Soil Carbon Affect Soil Health?

Soil that doesn’t have the right levels of minerals, acidity, or oxygen won’t be able to sustain life.

So, how does carbon affect soil health?

Well, soil carbon is an important factor when it comes to soil fertility and the ecosystem’s overall ability to function.

In fact, strong carbon levels are a sign that everything is functioning properly.

Carbon is a main energy source for microorganisms, which, in turn, produce other nutrients such as nitrogen and phosphorus.

These nutrients are then used up by the plants, keeping everything healthy and on track.

Because soil carbon is directly related to organic matter, that means it has a direct effect on soil texture.

Soil with strong carbon levels will be softer and more malleable, enhancing water retention abilities and increasing oxygen levels–all important factors when it comes to the fertility of the soil and the health of the ecosystem.

So, soil carbon can be massively beneficial, but what are some factors that can influence carbon storage?

3. What Factors Influence Soil Carbon Storage?

Soil carbon storage isn’t influenced by just one factor.

Essentially every element that impacts organic matter has an effect on carbon levels and storage abilities.

But what are they?

Here are the main factors that determine soil carbon storage:

bulletClimate (Moisture)

The climate of where the soil is located can be a big determiner of soil carbon.

Warm weather causes organic matter to decompose quickly, leading to a decrease in carbon levels.

Rainy climates spark higher carbon levels due to an increase in organic matter content.

In the United States, average soil carbon levels are highest in the East, where it’s wetter, and lowest in the West, where it’s drier (with a few exceptions).

bulletSoil Texture

Soil typically has a sandy, silty, or clay-like texture, which determines the overall tilth.

A clay-like texture can hold more water, promote better oxygen flow, and distribute nutrients easier than other textures.

In turn, clay-like soil typically has higher rates of carbon than silty or sandy soils, which have less organic matter, moisture, and oxygen.

bulletTopography

The topographical location of soil can play a big role in soil carbon.

Soil found at the bottom of the hill will typically have higher soil carbon levels.

Why?

The soil texture tends to be more clay-like, and the water running off the hill increases organic matter content and also slows down the decomposition of that matter.

The result is a localized area of soil carbon.

bulletPlant Productivity

Plant growth leads to organic matter, and organic matter leads to soil carbon.

But the size of plants also determines carbon levels.

Larger plants have more biomass, which results in larger quantities of organic matter.

With that being said, there are a number of other factors that determine how much organic matter a plant produces, such as the species, the environment, and the growth stage.

bulletLand Use and Management Practices

The way land is used will directly impact soil carbon levels in either a positive or negative way.

Practices like mono-crop agriculture and tillage are going to decrease organic matter content, cause soil erosion, and weaken the soil’s ability to retain water–reducing soil carbon levels.

On the other hand, using cover crops, fluctuating crop species, and reducing tillage will improve soil carbon levels.

4. Is Excess Soil Carbon a Problem?

Excessive carbon levels in soil are possible, but it’s generally not a problem in natural ecosystems.

However, when this does occur, it can create serious issues.

Overly high levels will make the soil less fertile, increase the chances of waterlogging, and ultimately damage the overall makeup of soil.

An excess of soil carbon can also lead to more organic matter content and microbial activity, which would lead to higher CO2 emissions (see the section on soil respiration for more information).

So, although abnormally high levels of soil carbon are rare, it still needs to be monitored to ensure that plants have the ideal environment to grow and prosper and that ecosystems stay strong and healthy.

5. What Is the Difference Between Carbon Storage and Sequestration?

Carbon storage and sequestration and two parts of the same system.

One refers to obtaining carbon, and the other refers to holding on to carbon.

Let’s check out each one and talk about their differences.

bulletCarbon Sequestration

Soil has a natural ability to pull CO2 out of the atmosphere and distribute it throughout plants and organic matter.; however, soil depends on the photosynthesis process within plants to achieve this.

The overall health and fertility of the soil will determine how much carbon it is able to sequester.

Soil that doesn’t have a fertile environment for plants to grow will sequester much less and have minimal organic matter.

Carbon, as we’ve discussed, also gets into soil through the decomposition of organic matter, but in general, carbon sequestration refers to the process of taking carbon out of the atmosphere.

bulletCarbon Storage

Carbon storage refers to soil’s ability to hold onto carbon in various forms and ways.

As carbon is sequestered by plants and moves down to its roots, it is released and used as energy by soil microbes, keeping it there for an extended period of time.

Certain carbon compounds will also link to soil minerals, resulting in a long-term storage process.

Additionally, carbon can move past the topsoil layer, where it’s less likely to escape or be used.

6. Why Does Carbon in Soil Help Plants Grow?

Carbon levels are directly related to the overall health of soil.

When more soil carbon is present, it’s an indicator that there is organic matter that is rich in nutrients that plants need to grow.

Organic matter also positively impacts the soil texture.

The soil will be much more malleable, enhancing water-holding abilities, nutrient availability, and soil biodiversity–all crucial factors when it comes to the growth of plants.

When soil carbon levels are adequate, it will also protect the pH levels from fluctuating.

Plants prefer a specific level of acidity or alkalinity, and if that balance gets thrown off, it can be detrimental to the ecosystem.

So, carbon is a crucial factor that helps provide nutrients for plants and microorganisms and maintains the overall texture and structure of the soil.

7. What Type of Carbon Do Plants Prefer?

When it comes to carbon, plants prefer the carbon-12 isotope.

Why?

Well, the carbon-12 isotope is the most abundant and stable, and plants have evolved to prefer it for the sake of survival and reproduction.

Other isotopes, such as carbon-13, aren’t as readily available.

8. How Does Soil Carbon Sequestration Helps Fight Climate Change?

Everyone is talking about climate change and the massive repercussions we could face if new strategies aren’t implemented soon.

Companies are producing more electric cars and sustainably made goods, but the threat of climate change still lingers.

Well, one part of the solution is right under our noses–or feet, rather.

Soil’s ability to sequester and store carbon makes it an important ally in the fight against climate change.

In fact, it has been estimated that all of the world’s soil is responsible for sequestering more than 10% of CO2 emissions caused by humans.

Those numbers could be increased if countries began taking their soil management more seriously and looked for ways to enhance soil’s ability to sequester carbon.

Of course, this would be a difficult task as soil carbon is greatly determined by natural forces.

Research has recently been done to see how plants operate in high-CO2 environments.

What they are finding is that plants begin to use water more efficiently, which leads to a more effective photosynthesis process.

An improved photosynthesis process allows plants to grow larger than usual and sequester and store more carbon.

Scientists are hoping that plants’ natural reaction to increased levels of CO2 will help humans in the climate change battle.

So, as the threat of climate change continues to grow, don’t be surprised if you see the United States and other countries put more emphasis on soil to help solve the problem.

9. Does Soil Sequester More Carbon Than Trees?

When it comes to sequestering carbon out of the atmosphere, soil is able to remove more than trees.

Of course, trees are an important part of Earth’s natural carbon cycle, but there’s simply just a lot more earth than there are trees.

A study from 2018 by the University of California, Davis, found that grasslands, in fact, sequestered and stored more carbon.

It also concluded that because grasslands are less impacted by natural disasters, such as wildfires and droughts, they are a more resilient and reliable carbon storage system.

However, although grasslands have proven to be more effective, that doesn’t mean trees don’t play an important role in managing soil carbon levels.

One mature tree, on average, sequesters about 48 pounds of CO2 per year.

Over its lifetime, that adds up to around 11,000 gallons of carbon.

Globally, there are about 3 trillion trees, so, as you can see, trees are not something to brush aside when talking about sequestering and storing carbon.

Both grasslands and trees need to be properly managed if we want to get a handle on the increasing levels of CO2 in the atmosphere.

10. Does Soil Release CO2?

So, you know all about how soil is able to sequester and store carbon, but does it also release it?

It sure does!

But let’s be clear, soil releases less CO2 than it takes in.

The process is referred to as soil respiration (it’s a natural process that occurs throughout all soils).

Soil respiration occurs when microorganisms, including fungi and bacteria, consume organic matter and convert the material into energy.

CO2 is created as a bioproduct.

This process is an important part of the global carbon cycle.

There are a few factors that determine how much soil carbon is released.

bulletTemperature

bulletSoil texture

bulletMoisture

bulletOrganic matter content

bulletpH levels

The rate of organic material content and microbial activity is directly linked to how much carbon soil is released.

If the soil has a clay-like texture, sufficient moisture, and balanced pH levels, it will both store more and release more CO2.

Additionally, temperature determines how active microbes will be.

Higher temperatures tend to stimulate activity, leading to increased rates of respiration.

Final Thoughts

Soil carbon has a lot of moving parts, doesn’t it?

CO2 is a crucial competent of soil and vegetation’s ability to grow; without it, well, the whole world would virtually come crumbling down.

Luckily, soil is a master at the process of sequestering CO2 from the atmosphere and using it to benefit plants and microorganisms.

As climate change becomes more of a pressing issue, utilizing soil’s natural ability seems like a logical solution, and there are already many researchers looking at ways to enhance soil carbon storage.

So, if you want to do your part and remove a bit of CO2 from the atmosphere, go check the soil on your property.

With a little love and care, your soil will be the perfect host for plants and be able to store much more carbon!

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Erika Gokce Capital

Disclaimer: we are not lawyers, accountants or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.

Erika

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