‍→ How do soil bacteria improve soil health and contribute to carbon sequestration in regenerative gardening?

Soil bacteria improve soil health through the:
- decomposition of organic matter
- enhancement nutrient availability
- symbiotic relationships they form with plants

They contribute to carbon sequestration through the:
- formation of soil aggregates that store carbon
- support of plant growth, which pulls more CO2 from the atmosphere
- natural drive to eat carbon themselves, which stores it in the soil

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Discover the unseen heroes beneath our feet: soil bacteria. These microscopic powerhouses not only enhance garden health but also play a pivotal role in fighting climate change by sequestering carbon.

Soil Bacteria: The Invisible Engineers of Our Ecosystem

Soil bacteria are tiny organisms that live in soil all over the world - including our gardens. They all do different jobs to keep the soil healthy. This in turn means that our plants are healthier, too!

They are the most populous demographic among all soil microbes. Additionally, as single-celled organisms, they are the smallest in size among soil microbes.

There’s such a variety of different bacteria, and they each hold unique roles in the soil microbiome (NSW DPI).

Soil Bacteria Transform Organic Waste into Garden Gold

Decomposition is the breakdown of organic matter. For example, fallen leaves naturally decompose and are no longer left on the soil surface after a few months.

The decomposition of organic matter is also what turns plant and animal materials into nutrient-rich compost. Bacteria are vital to the beginning states of organic matter breakdown (NSW DPI).

As they break down organic matter into smaller pieces, bacteria facilitate the process of releasing the nutrients stored in the decomposing materials. Now those nutrients are available for plants (soil health).

In fact, bacteria are considered the most important component of decomposition in compost piles (TAMU).

The decomposition process carried out by bacteria:

• improves soil structure
• increases soil organic matter
• makes nutrients more available for plant intake (Plants Basel)

Bacteria Partner with Plants to Help them Gain Nitrogen

This relationship is known as symbiotic - a kind of I’ll scratch your back if you scratch mine kind of thing.

An example of this is the bacteria that support legumes in “fixing” nitrogen in the soil. These bacteria essentially turn gaseous nitrogen from the air into a usable form. In other words, they “fix” it for the plants, since the plants can't utilize gaseous nitrogen. Nitrogen is an essential element for plants, as it supports green plant growth (soil quality).

Another way that bacteria support plants with a nitrogen source is through decomposition. As bacteria decompose organic matter, the nitrogen content in these materials is transformed into ammonia, which plants can utilize. Other bacteria change that ammonia into nitrates, which the plants can assimilate easily (Britannica).

→ Learn more about nitrogen fixation and regenerative gardening in our article here

How Soil Bacteria improves Soil Structure

Some bacteria make different polysaccharides which cause soil particles to stick together. This binds minerals and carbon together in a very stable way. This type of soil is called an “aggregate.”

Aggregates:

• prevent soil erosion
• help with optimal water porosity
• serve as communities for microbial life

In fact, around 70% of soil bacteria live inside of aggregates (Applied and Environmental Microbiology).

Building Resilience: Bacteria's Role in Plant Health

Similar to the beneficial bacteria in our gut, some bacteria keeps us healthy.

Here are some ways that soil bacteria supports plant growth and resilience:

Bacteria enhances plant nutrient uptake and health

Here are some examples of how bacteria create a symbiotic environment with plants:

• Boost nutrient absorption: Bacteria help plants access essential nutrients from the soil.
• Increase resilience: Bacteria can support plants to survive through environmental stress
• Climate Adaptability: Beneficial soil bacteria can help plants be more likely to thrive in our changing climate (Frontiers).
• Drought Resistance: Bacteria help plants to survive through periods without water (Science Direct).

Biological control of plant diseases

Beneficial soil bacteria help fend off harmful plant diseases. Here are a few examples:

• Bacterial wilt in the nightshade family can be prevented all together by beneficial plant bacteria.
• Soil bacteria has been shown to support major crops like wheat, rice, and corn.
• Certain helpful bacteria fight off harmful nematodes like root-knot nematode.

Bacteria in the World of Regenerative Gardening

Regenerative farmers and gardeners have two main goals:

1. build soil health to grow more robust plants
2. build soil health to sequester carbon.

Many of the regenerative principles - such as mulching, keeping the soil planted, and cover crops, all build organic matter levels in the soil.

According to Nature, organic matter is composed of soil microbes and decomposed organic materials.

Microbes and decomposed organic materials are very carbon-rich.

The more organic matter present in the soil, and thus, the more microbes, the higher the soil carbon levels (CSU).

Other regenerative practices, such as no-dig methods, not disturbing the soil, and building up soil layers minimize damage to the soil microbiome and minimize carbon release.

Carbon Sequestration: Bacteria’s Role in Climate Mitigation

→ What is the role of soil bacteria in carbon sequestration?
In simple terms, carbon sequestration is a way of storing excess atmospheric carbon dioxide elsewhere. In this instance, it’s stored in the soil.
Since this excess carbon dioxide causes climate change, we’re trying to sequester as much of it as possible to help the environment.

Bacteria play an underappreciated yet vital role in capturing atmospheric carbon dioxide and storing it in soil. They function through several mechanisms:

Photosynthetic Bacteria:

• Some bacteria can gain energy through photosynthesis!
• This means they transform atmospheric carbon into a soil-table form (Life Basel).

Symbiotic Relationships:

• Some bacteria are in friendly relationships with plants
• They both benefit from interacting with each other.
• These bacteria get carbon compounds from the plants. During photosynthesis, the plants take in carbon dioxide from the atmosphere and turned it into these compounds (bbc, nih).

Decomposers:

• By breaking down organic matter, bacteria transform carbon into stable forms that integrate into the soil matrix (Cornell).

Predatory Dynamics:

• Bacteria that consume other microbes accumulate carbon within their cells
• The carbon eventually gets deposited in the soil upon their death (energy.gov).

→ Soil microbiota like bacteria are the unsung heroes of carbon sequestration. In fact, soil microbes are the largest factor of soil carbon storage levels.

Simple Actions to Boost your Soil’s Beneficial Bacteria Population: Best Practices for Regenerative Gardeners

Learn how you can feed beneficial soil bacteria AND sequester carbon at the same time with these regenerative practices:

1. Give Microbes a Blanket of Food

Mulching is like tucking the soil in with a cozy comforter of food. Mmmm, food blanket.

Mulch helps with carbon sequestration by feeding soil bacteria:

• Mulch supports carbon sequestration because it is a source of organic matter for soil bacteria and other microbes.
• The decomposers feed on the mulch, and then transform the carbon from the organic matter into more stable forms.
• This helps the carbon to stay within the layers of the soil (Springer).

2. Grow More Microbe Food

Cover crops do the important work of continuing photosynthesis in the soil once the cash crops are harvested. Typically, the soil would lay barren during the winter months. No plants, no photosynthesis, no well-fed microbes, no carbon sequestration. But when cover crops are in the soil, the process of photosynthesis can continue. Plus, the cover crops produce organic material that can be utilized as mulch.

Here's how cover crops help sequester carbon:

More Photosynthesis Time:

• For the carbon sequestration benefits of photosynthesis to occur, the soil needs to have living plants.
• Studies have proven that cover crops increase carbon storage in soils.

Organic Matter Multipliers:

• Once they decompose, cover crops enhance the organic matter in the soil, another crucial element for storing carbon.
• SARE performed a study that showed that cover crops feed bacterial life, fungi, earthworms, and other soil microbiota. This increases carbon storage in the soil.

3. Don’t Panic, use Organic Inputs (fertilizers, etc.)

Conventional farming utilizes synthetic inputs that contribute to climate change in major ways. With 300 times the warming potential of carbon dioxide, nitrous oxide is released into the atmosphere with the application of synthetic nitrogen fertilizers.

Organic inputs are:

• less harmful to the atmosphere
• better for the health of our waterways
• more supportive of the landscape and plant healthas a whole
• work WITH our soil microbe heroes to deliver nutrients to the plants. In contrast, synthetic inputs bypass the microbes all together, and as the microbes become unnecessary, their populations decrease (Teeming with Microbes).

4. Variety is the Spice of Life

Regenerative gardening implements polyculture, or diverse plantings, whenever possible. It’s the opposite of monoculture. Plants like to mingle, and the soil microbes like a variety of plants to hang out with, too. It's like a sampler platter of different dishes vs. a pile of just lettuce on a plate. I mean, lettuce is great, but which one sounds better? 

A study published in Nature Communications  shows that plant diversity increases soil microbial activity and soil carbon storage:

• Research suggests that elevated carbon storage happens in hi plant diversity areas
• The cause of this is a more diverse soil microbial community
• more pants=more microbes=more carbon = more soil health

Polyculture has other benefits too: with increased biodiversity come:

• less pest pressure
• less disease
• a more robust soil microbiome.

5. Compost is key

The process of making compost in and of itself reduces the amount of methane emissions that your food waste would create if sent to the landfill.

It also has another benefit fo your garden - it’s that amazing microbe-rich organic matter we’ve been talking about!

As organic matter increases, the plants are able to grow better and actually sequester more carbon.

In fact, a 19-year study found that in semi-arid soils, compost addition was a major component of carbon storage potential.

Conclusion: The Gateway to a Living Soil

It can be easy to think of all bacteria as disease-causing harmful organisms.

But not everything in the bacterial realm is so one-sided.

As you’ve learned in this article, soil bacteria is a true hero in our ecosystem. From meaningful relationships with single plants to a range of carbon sequestration potential, beneficial soil bacteria do a lot of invisible work to keep our plants and planet healthy.

Now that you understand the role of soil bacteria in carbon sequestration, how might you change your gardening practices to support these microscopic allies?

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