Most people can distinguish between an abiotic object and a biotic organism. Biotic organisms have eyes, eat, sleep, or are similar to us in some way, while abiotic objects are the opposite 一 they aren’t living organisms. Your garden plants are certainly biotic, but things aren’t that clear regarding the soil they grow in.
Soil is considered abiotic, but there are many biotic factors within it. Abiotic or non-living things in your garden include the sunlight your plants use to photosynthesize, the water that hydrates them, the soil they’re planted in, and the many nutrients within the soil that help them grow.
In the rest of this article, I’ll explain the difference between biotic organisms and abiotic factors. Then, we’ll talk a little about the many biotic things in your soil. We’ll also classify what things in your garden are considered living and what things aren’t.
Soil Is Abiotic, but There Are Many Biotic Organisms in It
The question itself is understandable. Things that are biotic – or are living – are considered parts of an ecosystem. However, because the soil is an essential part of an ecosystem and directly relates to biotic features such as pests, plants, and animals, you may have thought that soil was also considered biotic.
By definition, the soil is considered abiotic. Like sunlight, water, and minerals, it is a non-living factor that affects the environment rather than living in it.
However, this isn’t to say that there isn’t a living – or biotic – feature to your soil. There are dozens of bugs, microorganisms, and plants (if you are a gardener!) living within your soil. These are biotic factors within the soil, which is why some may consider soil both living and nonliving.
Scientifically speaking, the soil is abiotic, while the organisms living within it are biotic. It’s the same way you live (biotic), but your house does not (abiotic).
Soil is not considered abiotic because it is not a living element. It’s made up of living things, such as worms and other organisms, which are all part of a complex food chain. It also contains organic matter that decays over time to release new plant nutrients.
This is why having good soil is important in agriculture: the health of your plants depends on what you put into your soil!
The Difference Between Biotic and Abiotic
Biotic and abiotic are hard to distinguish, not just because the names are similar. Sometimes, it can feel like something belongs to both categories. However, they’re essentially the opposite of each other.
Abiotic factors are those that do not depend on life for their existence. For example, water is an abiotic factor because it does not require any living organism for its existence or maintenance. Biotic factors are those that do require life for their existence or maintenance.
Biological factors include all living things in an environment — including animals, plants, and microorganisms such as bacteria. The term “biotic” is often used interchangeably with “biological” when referring to these organisms or processes involving them.
For example, “biological processes” refer to photosynthesis and respiration in plants and animals.
Abiotic factors, such as temperature, water content, and light exposure, can influence whether a species can survive in an area. Biotic factors include other living organisms that interact with one another.
Some of the criteria used to determine whether something is living include:
- Reproductive capabilities: Biotic organisms reproduce by either asexual or sexual reproduction methods. Asexual methods do not require two parents to produce offspring, while sexual methods require two parents, each contributing half of the genetic material for offspring to be produced.
- Waste excretion: Biotic organisms usually excrete waste.
- Respiratory capabilities: Biotic organisms utilize oxygen to respire.
- Ability to utilize nutrients for growth and survival: Biotic organisms need to obtain nutrients from their environment or eat.
Plants are multicellular eukaryotic organisms that obtain their energy through photosynthesis and store it in the form of starches, oils, and fats. And yes, even plants eat! Plants also need to get their water from somewhere, so they usually have some kind of root structure that allows them to get it from the ground.
Additionally, things that were once living are also considered biotic. For this reason, even decomposed organisms within your soil are more biotic than the soil itself.
This video helps to break down this topic even further, giving you a visual classification of many things people commonly say are biotic or abiotic when they’re the opposite:
As you can see, there are a few factors for determining “life” or the biotic characteristic of any given thing.
Composition of Soil and the Biotic Organisms in It
Soil is mostly made up of the mineral particles of rocks, sand, and silt (particles smaller than sand). The rest is air space, organic matter, and water molecules. Soil also contains certain chemicals like carbon dioxide, oxygen, nitrogen oxides, hydrogen sulfide gas (characterized by rotten egg smell), and ammonia gas (smells like cat pee).
Mineral particles make up the largest chunk of soil composition. Most soils are 45% to 50% mineral, with the rest split between water, air, chemical elements, and organic matter.
Soil can be seen as a dynamic ecosystem due to the constant interactions between its biotic and abiotic components. Abiotic components include minerals, gasses, liquids, and energy. Biotic components include plants, animals, microorganisms, and other living organisms.
The concept of abiotic and biotic soil components is important because it helps us understand how these two groups can interact to create a healthy ecosystem. This understanding allows us to optimize our garden soil to meet specific plant needs.
For instance, altering the proportions of mineral particles, organic matter, water molecules, and air in the soil can help create a conducive habitat for soil organisms. These organisms help break down organic matter to release plant nutrients like nitrogen, so creating the best conditions for them to thrive can affect plant health and yield.
With this knowledge, you can alter soil characteristics, such as aeration and drainage (by adding organic matter, for instance), to improve biological activity. Doing that can help fix specific nutrient deficiencies in the soil, allowing plant species that would have otherwise struggled to thrive.
What Biotic Materials Are in My Garden?
Biotic materials in your garden are the living organisms and plants in your soil. These include animals and insects, garden plants and weeds, fungi, and microbes such as bacteria.
The biotic factors in your garden soil coexist with other abiotic elements such as rocks, minerals, water, and organic matter. These living organisms play a critical role in helping maintain a proper balance between the other soil components and can be especially helpful if you have decided to do vermicomposting.
Other factors within your garden, such as nutrients you add to your soil or the water you put over your plants, would also not be considered living nor biotic. These affect the ecosystem rather than play into it or adapt to it.
Is Fungus Considered Biotic?
Fungus is considered a biotic part of your plant ecosystem. They can reproduce, grow, and have other factors that make them a part of the biotic section in your garden.
Microorganisms are all around us, especially in our gardens. The term “microorganism” refers to any microscopic living organism. This includes fungi and protozoa (single-celled organisms).
These microorganisms can be helpful in the garden. For example, they help break down organic matter to release nutrients for your plants when you add compost to your soil.
Fungus, like your plants, is a biotic factor. Mold would also be a biotic element in your garden. Though you may consider it more closely related to your soil than your plants because of its appearance and texture, biologically, it’s more like your plants.
The addition of fungus in your garden may have thrown a wrench in your understanding because the nutrients within the soil aren’t usually considered biotic. Fungus is far from a nutrient, but it may feel closely related.
Soil is considered abiotic because it isn’t living. Things are living within the soil, but the soil itself is not a living organism. In the same way that you are alive and biotic, but the water you drink isn’t living, the things in your garden typically fall into two distinct categories. Your house has living people and living things like pets or plants, but it isn’t alive itself.