How Can I Achieve Healthy Plant Growth?

Published by Paul Clarke on

How Can I Achieve Healthy Plant Growth?


Revegetation project not going well? After forty years in the industry, we have seen this issue repeatedly where projects don’t meet project completion. Why waste money on reworks and processes that don’t work, which only hurts your reputation and puts you out of pocket? Knowing the reason why the grasses are not growing is the first step to achieving healthy growth on your site. It may boil down to an underlying issue to do with the soil. Therefore, it’s a good idea to get soil testing done so you can work out whether the soil is healthy enough to sustain plant growth. Having the right amount of nutrients in the soil is a delicate balance. Too much nitrogen or carbon can be detrimental to plant growth. Knowing the right ratio will help you develop a healthy soil that creates the right environment for microbial activity. Beneficial microbes are the key to developing sustainable plant growth as they provide essential nutrients. Keep reading to find out more about the importance of microbes for plant growth and how to create healthy soils with the right amount of nutrients.

Why is the carbon-to-nitrogen ratio important?

Carbon can be thought of as the building blocks of life, which work with nitrogen hand in hand to provide essential nutrients for plant growth. Look at the carbon cycle below, plants absorb CO2 through photosynthesis and convert it to sugars. They then feed some of these sugars to microbes in exchange for nutrients. Microbes play a crucial role in the carbon cycle by creating healthy soils for plants to grow in. They provide essential nutrients by pulling nitrogen from the air and converting it into a form that plants can absorb like ammonia and nitrate. Plants need the right amount of nitrogen at the right time and microbes in turn rely on plants for food. Understanding the importance of microbes in the soil will help you to achieve plant growth on your site.

carbon cycle

Why are Microbes important for plant growth?

When plants and animals die, microbes decompose them into organic matter, which is important for maintaining healthy soils for plants to grow in. The soil organic matter (SOM) helps plants and microbes by providing nutrients, improving the soil structure, retaining water, and stabilising pH levels. SOM levels need to be just right for plants to thrive. Therefore, maintaining an ideal balance between carbon and nitrogen in the soil is important for creating an optimal environment for plants to grow in.

soil organic carbon cycle

What is a healthy Carbon to Nitrogen Ratio?

An appropriate carbon-to-nitrogen (C: N) ratio would be around 10:1 to 12:1. So, for every 10 to 12 parts of carbon there should be 1 part of nitrogen in the soil organic matter. This ratio gives microbes enough nitrogen to grow and adequate carbon for their energy to survive. SOM levels can be affected by organic materials such as crop residues, animal manure, cover crops, and perennial grasses and legumes. The soil acidity level can also affect the microorganisms’ ability to change nitrogen into a usable form for plants to absorb.

How to maintain the soil nutrient levels?

soil nutrients

Ameliorants like lime, gypsum and compost can improve soil nutrient levels on revegetation projects. Lime can improve the soil by increasing the pH level, making it more alkaline. This helps the microbes convert nitrogen into a usable form for plants to grow. Gypsum helps the soil by breaking up clay, improving the soil structure and fertility, and promoting root growth and drainage. Compost is organic matter that nourishes plants, supports microbes, and retains moisture. To create the best conditions for plants to grow, test the soil and use a mix of these ameliorants according to the results to achieve successful growth on your site. Our applications provide a variety of mix designs to suit your site’s problems. Our Compost Blankets are especially suited to areas lacking topsoil as they provide all the nutrients plants need to grow. They are even maintenance-free, which means all you need to do is wait for rainfall. You can read more about them here.

How much Carbon can be stored in Soils?

Storing CO2 in the ground as soil organic carbon (SOC) helps fight climate change as it reduces the amount of CO2 in the atmosphere. Scientists know this process as soil carbon sequestration. When the microbiology of the soil is not thriving, carbon cannot be stored, and it leeches and disappears. This affects the soil’s ability to retain moisture. Many Australian agricultural soils have the potential to store more organic carbon because they have lost a lot in the past. The actual amount of SOC present in the soil is dependent on several factors such as rainfall, temperature, vegetation, and soil type.

How much of the Soil Organic Carbon that enters the Soil stays there?

When microorganisms break down organic carbon in the soil, they release a small part of it as carbon dioxide back into the air. About one ton of organic carbon is equal to about 3.67 tons of carbon dioxide in the air. The percentage of dead plants and animals turning into organic material can be up to 30%. This rate depends on soil type and climate. In Australian agricultural soils, this rate often falls below 30%. Soils that contain more clay keep more organic matter, including organic carbon, than sandy soils.

Benefits of Increasing Carbon Levels in Soils:

By adding compost and organic mulches to the soil, you can improve its structure. This is done by increasing the amount of carbon-rich organic matter. It promotes the formation of aggregates, enhancing soil aeration, water infiltration, and root development. Organic matter acts as a sponge, absorbing nutrients like nitrogen, phosphorus, and potassium. This helps plants by reducing leaching, which prevents nutrient wastage and water pollution.

Increased microbial activity: organic carbon provides a food source for beneficial soil organisms. Microbes break down organic matter and release nutrients that plants can absorb. Healthy microbial activity contributes to overall soil fertility.

Better water retention: soils with higher carbon levels can store more water, reducing the need for irrigation and aiding plants during droughts.

Carbon Sequestration: carbon can be stored in the soil, which can contribute to mitigating climate change by reducing greenhouse gas levels.

Drawbacks and Challenges of Increasing Carbon Levels:

When there is too much carbon and not enough nitrogen, soil nitrogen gets tied up by microbes breaking down the carbon-rich material. This can temporarily lead to nitrogen deficiency in plants, causing slow growth.

Collecting, transporting, and applying organic materials for carbon increase can be labour-intensive. Also, straw or hay could have weed seeds or pathogens in it. If you add these materials without composting or heating, weeds and diseases can get into the soil.

Slow decomposition: some carbon-rich materials, like wood chips or sawdust, decompose slowly. During decomposition, they can hold onto nitrogen, which can affect nearby plants temporarily.

Certain carbon-rich materials, like pine needles or peat moss, can make soil more acidic over time. This might be beneficial for acid-loving plants but detrimental to others.


The soil must always have growing plants that are photosynthesizing and feeding the carbon down through their roots into the soil which feeds the microbes. In exchange, the soil microbes feed the plants essential nutrients. This process is what builds carbon in the soil. When microbes are not active or present in the soil then carbon cannot be stored, which results in the soil losing moisture.

Higher carbon levels in soil can greatly improve soil health, fertility, and the environment but you need to balance the carbon-to-nitrogen ratio and monitor soil health for good plant growth.

Now that you are aware of the importance of microbes for plant growth and creating healthy soils, you should get a soil test on your site to help you determine the amount of nutrients available and how to fix any deficiencies in the soil. Pay attention to the carbon, nitrogen, and organic matter levels in the soil as these are important to microbes, which help grow healthy plants and grasses.

Find out more on how to achieve successful growth by reading our article, Sustainable Growth in Poor-Quality Topsoil.

For more in depth info on soil microbiology, check out Walter Jehne’s webinar.

If you’re ready to start Hydromulching, check out our compost blanket applications.