What is Organic Matter? How Does It Benefit My Garden


Picture of cupped hands holding soil and worms

If you are a gardener, you have probably heard of organic matter.  Soil organic matter (SOM) is a critical component for your crops. Failure to use organic matter in your garden will affect the plant’s health and yield quality.

Organic matter refers to a wide range of carbon-based organic compounds. It performs a critical role in your garden by feeding microbial life, building soil structure, aids with water retention, and prevents soil erosion.

This post will help you understand what organic matter is, how it helps your plants, and how to create good quality organic matter. Read on and find out all these and more.

What makes up organic matter?

Living micro-organisms are a critical component of soil organic matter. These micro-organisms include protozoa, bacteria, algae, fungi, and viruses—these makeup for about 10% to 40% of the soil’s organic matter. 

Some studies suggest that living organisms found in the soil represent a quarter of the living population. Earthworms and insects in the soil are also part of this vital group in the soil.

As these living organisms feed on the soil matter to obtain food and energy, they break it into finer components useful for the plants. In the process, they also help in mixing these components in the mineral soil.

The bi-products and waste from earthworms and fungi help bind soil particles together. Also, as these organisms move through the soil, they help aerate the soil and enhance its water retention properties.

Plant remains to make up for a significant part of soil organic matter, and out of this, up to 90% is made up of water or moisture.  The amounts of stable organic matter, also called humus, are about 40% to 60% of the total soil quantity.

The dry material is mainly carbon, oxygen, and hydrogen. Other components found in smaller quantities include calcium, potassium, magnesium, phosphorous, nitrogen, and sulfur. All these compounds are critical for a plant’s growth and development, and they define the fertility of the soil. 

The decomposition rate of organic matter in the soil depends on various factors, including environmental conditions such as temperature and soil conditions such as pH levels, moisture content, and biological activities.

There is so much to do with organic matter and its importance that I wrote a dedicated article covering all the aspects around this subject, and you can read it here. What Is Organic Matter, And Why Is It So Important.

Benefits of organic matter to my garden

picture of gloved hands placing vegetation into plastic compost bin

The levels of organic matter define soil fertility or productivity. It is the basis for healthy plant growth and productivity. If you intend to start farming, you need to understand the role of organic matter.

Organic matter protects the soil and plant roots from harsh weather conditions such as excess sun, rainfall, and wind. It applies more to the organic matter in raw residue found on the topsoil, preventing soil erosion.

If you allow the organic matter to be used up, you distort your garden’s ecosystem as it deprives the useful living organisms in the soil of their food source.

Since it is derived mainly from plant residue, organic matter contains the necessary nutrients for the plants in your garden. When well decomposed (humus), these nutrients are in their simplest forms absorbable by plant roots for the benefit of plants.

What happens to organic matter over time.

Over time, soil organic matter keeps decomposing. As plants take up the necessary nutrients from the soil, they become deprived, declining fertility levels. For this reason, a farmer or gardener needs to keep boosting soil fertility by adding compost or humus.

The more decomposed the humus, the more beneficial it becomes for plants. As it decomposes, it breaks down into smaller particles, making it easier for the nutrients to leak into the soil.

This process, also known as mineralization helps leads to the production of simpler particles in the form of essential nutrients or macronutrients: nitrogen, carbon, ammonium (NH4+), and nitrate (NO3) from proteins, phosphorous, calcium, potassium, oxygen, carbon dioxide and sulfur among other micronutrients. The smaller humus particles are also in contact with more soils particles.

Does organic matter help build numbers of fungi and organisims

Fungi and other micro-organisms within the soil help improve the soil structure of your garden. They do so through the aggregation of soil particles into larger particles. These particles have better aeration properties, allow water infiltration, and are more resistant to soil erosion.

Soil organic matter improves soil infiltration. Soil with high organic matter levels has better drainage properties. It is less likely to get waterlogged in excessive rainfalls or overwatering.

Plant roots require oxygen for respiration, a process that provides them with food. In cases where the soil is saturated with water, air cannot infiltrate through the soil particles. As a result, the plant roots suffocate, starve and start to rot.

Additionally, waterlogged soils are at the risk of accumulating by-products of microbial metabolism of roots such as plant toxins (CO2, Fe2+, and Mn2+)

It is also important to understand that different plants take up nutrients at different rates. All in all, as the levels of organic matter decrease in the soil, it becomes more difficult to grow healthy plants. Organic matter affects soil fertility factors such as water availability, air infiltration, parasites, erosion, and diseases.

Does organic matter save money in the garden

Gardening becomes more expensive when the organic matter in the soil is depleted. It makes the gardener more dependent on artificial practices such as the use of fertilizers and pesticides.

For healthy plant growth, the organic matter in the soil should be between 1 to 6 percent. For every 1% increase in the organic matter content, there is about a 12% increase in plant yield.

Organic matter in the soil stimulates root growth through the availability of nutrients. It also alters the expression of certain genes. It is also facilitated by the micro-organisms in the soil, which produce certain substances in the form of chelating agents and plant hormones that stimulate root growth.

Chelating substances such as siderophores help in longer and more established plant roots. Also, free-living nitrogen-fixing bacteria provide plants with essential nutrients. Other bacteria also break down phosphorous from materials, making it available in simpler forms for plants to absorb.

Improving soil texture and colour with organic matter

Organic matter improves the color and texture of the soil. Adding humus to sandy soil, for instance, will make the soil marker which makes it absorb more warmth during cold seasons such as spring. Higher soil temperatures are essential for the germination of seeds and root development.

Organic matter helps protect plants from naturally occurring harmful chemicals. As soils become deprived, they get more acidic. The result is that certain substances, such as aluminum which is harmful to plants, dissolve and absorb plant roots.

When the soil has sufficient organic matter, it binds aluminum and other toxins, making them harmless to plants.

Organic matter also prevents the leaching of pesticides into underground water. It allows these chemicals sufficient time for detoxification by microbes in the soil. Some micro-organisms in the soil alter the chemical structure of chemicals, making them harmless for plants, animals, and humans.

How does organic matter help the nitrogen cycle?

Organic matter is essential for the carbon cycle, which helps eliminate carbon dioxide in the atmosphere. Accumulation of carbon dioxide in the atmosphere results in the greenhouse effect, a major cause of climate change.

Soil organic matter helps in the process of the nitrogen cycle. Without manure and fertilizers, plants do not always have sufficient nitrogen, which is essential for growth. Plants derive up to 50% of their nitrogen needs from organic matter in the soil.

They often take up nitrogen in the form of nitrate and smaller quantities of ammonia. Since the forms of nitrogen in the soil are not always absorbable by plants, micro-organisms help break up organic matter into ammonia and nitrate, which plants readily use.

Animal manure is an excellent source of nitrogen for plants. Also, nitrogen-fixing bacteria in the soil convert nitrogen in the air to nitrates useful to the plant. The alternative source of nitrogen for your garden is by use of fertilizers which only last for a shorter period and do not improve the soil quality.

Another benefit of adding organic matter to your garden is that it helps in water retention. Organic matter acts as mulch for your garden covering the soil and preventing water loss through transpiration. For this reason, you do not need to water your plants as often.

There are so many reasons why organic matter is good for the garden, and in this article, I cover them in more depth. Check it out here. Why Use Organic Matter For The Garden.

How to create good quality organic matter in your garden

To increase the fertility of your garden, you need to create good organic matter. It is a long-term practice that requires consistency. In this section, we will be looking at various helpful tips for enhancing the fertility of your garden.

You should add compost or manure to your garden to increase soil fertility. Compost works by improving the soil structure, increasing nutrients in the soil, enhancing the drainage and aeration of the soil. It also improves the soil pH, promotes root growth, and prevents certain garden diseases.

When you add manure, you also feed the micro-organisms in the soil and earthworms, which break down the material for plants uptake.

Proper tillage will help maintain the organic matter in the topsoil where it is most useful. It is advisable to limit the number of times you till your garden. Although tilling is at times necessary, it distorts the ecosystem of the garden soil.

As a result, tilling slows down microbial action, which helps break down organic matter in your garden. Also, tillage increases the rate of erosion.

It is critical to reducing erosion to conserve organic matter, which is often abundant in the topsoil. If you can prevent erosion in your garden, you are already protecting the organic content in the soil.

Growing cover crops will also help boost the fertility of your garden. Cover crops increase the fertility of the soil and also prevent erosion. They also limit the growth of weeds in your garden, reducing the need for weeding.

A frequent soil test for your garden will inform you what nutrients are lacking in your garden. After adding compost to your garden, you need to conduct a soil test every few years. It is good practice, however, to know what your soil requires before you add any amendments.

Soil testing may sound scary, but I have you covered, so check out this article I wrote which will take you through all the steps of soil testing your garden.

Soil test kits are available in most stores selling garden supplies. This equipment can determine the soil pH, potassium, magnesium, calcium, phosphorous, and sulfur content.

With a soil test, you also get to know the amount of organic matter in your garden and if there is a need to add more.

There are certain organic remedies for supplementing different nutritional deficiencies in the soil. Alfalfa increases the nitrogen, phosphorous, and potassium content in the soil.

You can alternatively use worm castings to increase the levels of nitrogen in the soil. Bone meal is an excellent source of calcium and phosphorous for your plants. In other cases, you could use all-purpose organic fertilizer.

Mulching the soil surface will also boost the fertility of your garden by preserving the organic matter content. Mulch creates a perfect environment for the action of microbes by maintaining a moist and warm environment underneath.

Additionally, mulch prevents weed growth that poses competition for nutrients in your garden. As the mulch decomposes, it also adds to the organic matter in the soil.

Crop rotation is also another helpful strategy that helps prevent the nutrient content in the soil from depletion. Proper crop rotation also prevents diseases and pests, keeping your soil healthy. You need to avoid growing the same type of crops at the same spot in a three-year cycle for proper crop rotation.

Conclusion

Soil organic matter is essential for the growth of healthy plants. Above, I have provided you with an in-depth understating of organic matter, why your crops need it and how to maintain a healthy garden.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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