What is the Soil Ecosystem?

Soil provides a habitat or living environment for a large number of different species of organisms as well as plants. It provides all the essential nutrients and minerals for plants to grow. All these together form the soil ecosystem.

Components of the Soil Ecosystem

Soil contains both biotic and abiotic factors and is composed of the essential elements that make up an ecosystem. Biotic factors consist of living things such as plants and insects, whereas abiotic factors consist of non-living things such as minerals, water, and air.

Soil testing is carried out by various researchers to identify the amount of biotic and abiotic factors present in the soil. These tests are also used to detect whether the soil lacks some specific and needed mineral or if it has too many minerals. Measurement is also carried out to detect the amount of water in the soil and how it varies from time to time. These tests are also helpful in detecting the presence and amount of any contaminants in the soil. Also, the percentage of heavy metals in the soil, its pH as well as soil nitrogen content is determined by these tests. All these measurements help determine soil health. The most commonly found minerals in the soil are potassium and phosphorus that support plant growth. Some other minerals are also found in the soil, such as calcium, magnesium, and sulfur, but these are less common. The biotic and abiotic factors together constitute the soil composition.

Importance of soil for the ecosystem

Soil serves as a life-supporting system. The humus in the soil helps in plant growth by providing them with essential minerals and nutrients like nitrogen, phosphorus, oxygen, carbon, and so on. They hold the plants by providing support to their roots and also hold water. Soil provides a shelter for various microorganisms that fix the nitrogen and decompose the organic matter that supports plant growth.

Soil plays an important role in the agro-ecosystems and ecosystem multifunctionality. It helps to collect the rainwater and prevents flooding by holding excess water. It provides the foundation for various agricultural, construction, environmental, and urban activities. The key functions of soil in the ecosystem are as follows:

• Production of food and humus, that is, the organic matter released into the soil by dead plants and animals that aids in moisture retention.
• Source of various raw materials essential for life.
• Provides heritage
• Prevents flood
• Serves as a basis for various man-made architecture.

Due to these key functions, the soil is itself considered an ecosystem. The absence of soil leads to soil erosion which serves as a disaster for human life. Healthy soil is a critical resource for combating food crises, such as the one caused by the COVID-19 (coronavirus disease of 2019) pandemic.

The soil biodiversity is getting exposed to various biological, chemical, and physical stressors due to intrusion by human populations. Several contaminants from the human populations affect the structure, function, and services of the soil community. Soil biodiversity and soil health are altered due to activities such as mining, agriculture, construction, farming, and waste disposal.

Soil erosion

Soil erosion is defined as the removal of the upper layer of the soil. It can result from various agents such as water, air, plants, animals, and humans. The loss of soil may result in a lower surface water level, reduced crop production, and blocked drainage networks. Due to the removal of the soil layer, it becomes difficult to hold excess rainwater, which may give rise to flood.

Soil ecosystem engineer

Soil provides a self-organized ecological system for the interaction of different soil populations. The earthworms, termites, microbial population, and ants play an important role in providing habitat for other soil habitants. They control their various activities by physical and biochemical processes. Together they are referred to as soil biodiversity/ecosystem engineers. They help in the degradation of organic matter in the soil that supports plant roots and their growth. These soil community engineers trigger the production of various energy-rich signaling molecules that stimulate several biological and ecological processes, such as the degradation and synthesis of organic substances. These processes mediate the soil ecosystem's multifunctionality.

Earthworm, the soil ecosystem engineer

Earthworms are treated as soil ecosystem engineers because they can alter the environment of the soil by changing soil properties. They can greatly enhance soil's bulk density, porosity, infiltrability, and hydraulic conductivity. Earthworms actively stimulate the distribution of the plant-soil roots so that various essential nutrients and minerals that are provided to plants through roots can be easily available.

Earthworm activity enhances root distribution so that immobile macronutrients such as phosphorous and other micronutrients, which are absorbed by the plant through root interception, are easily available to the plants.

Effects of soil on ecosystem

Soil serves as a link between air, water, rocks, and organisms and serves several functions in the ecological system. These functions include:

Habitat

Soil is an environment for plant seeds to grow. The top layer of soil that contains humus provides essential nutrients and minerals as well as water that helps to nurture the plants and supports their growth. These plants, together with other plants and organisms, constitute an ecosystem. These plants, in turn, provide habitat and food sources for other organisms.

Temperature regulation

Soil temperature plays an important role in the various chemical and biological processes that occur inside the soil, including seed germination and microbial decomposition. In colder environments, these processes are less common as compared to that of warmer regions, due to which there is more carbon in the soil in colder regions.

Water filtration

Soil helps to hold the excess rainwater from where it can be taken up by plants, microorganisms, and other living things. Also, soil helps to direct rainwater to the nearby oceans and lakes, helping in harvesting water. Soil also helps to filter rainwater. If harmful pollutants are present in the rainwater, then soil acts as a filter and captures all the contaminants, leaving behind clean water, which is then passed down into clean water sources.

Waste decomposition

Soil serves as an excellent source that converts various waste into newer products that are utilized by other microbes. When a living organism dies, it falls into the soil and by various biological and chemical processes gets decomposed and is converted to new products which are used by other microorganisms that live in the soil.

Soil ecology

Soil ecology is the study of the interaction between the various microorganisms present in the soil and biotic and abiotic components of the soil environment. Manuel Delgado-Baquerizo, J. M., and colleagues conducted a global field survey in urban green areas and discovered that urban soils are important hotspots for soil bacterial, protist, and functional gene diversity. This gene diversity also preserves a globally uniform microbial soil community.

Soil ecosystem services

These services are the benefits that people can obtain from the ecosystem. Soil plays an important role in the provision of soil ecosystem services. Soil ecosystem services serve as a crucial aspect of human life and trigger the production of various ecosystem goods and services such as:

• Food and fiber
• Energy resource
• Purification and storage of water
• Filtration, neutralization, and purification of the contaminants
• Regulation of natural hazards
• Protection against natural calamities
• Temperature and climate regulation

These soil ecosystem services benefit not only humans but also other flora and fauna. These soil ecosystem services rely on the functioning and properties of the soil. Various kinds of healthy soil enrich the soil biodiversity that in turn guarantees the establishment of soil ecosystem services.

Soil food web

The soil food web constitutes a vast diversity of organisms. They include bacteria, fungus, algae, protozoa, earthworms, insects, and plants. The soil food web forms an integral part of landscape processes in various ways. The organic matter is decomposed by the soil organisms and prevents them from entering the water and turning into pollutants. Most of the organisms help in soil aggregation and porosity that further increase the infiltration process and reduce the chances of soil erosion.

Context and Applications

This subject is important in professional exams for both undergraduate and graduate levels, particularly in botany, plant physiology, agriculture, ecology, and so on.

Practice Problems

Question 1) Apart from biotic factors, what other factors does soil contain?

a. Abiotic
b. Semi-biotic
c. Biotic
d. Environmental
Answer- Option a.

Explanation- Abiotic factors such as minerals, water, and air are non-living components of an ecosystem that shape its environment.

Question 2) Which of the following is also a function of soil along with temperature regulation, water infiltration, waste decomposition?

a. Habitat
b. Water regulation
c. Water decomposition
d. Waterlogging
Answer- Option a.

Explanation- Soil provides a growing environment for plant seeds. It supplies necessary nutrients and minerals, as well as water, to assist nourish and support the growth of the plants.

Question 3) Which of the following factor(s) determines the amount of soil testing?

a. pH
b. Earthworms
c. Biotic and abiotic factors
d. Fungus
Answer- Option c.

Explanation- Various researchers do soil testing to determine the amount of biotic and abiotic elements present in the soil which helps to determine soil health. 

Question 4) Identify the soil ecosystem engineer from the following.

a. Fish
b. Ants
c. Nitrogen
d. Snakes
Answer- Option b.

Explanation- Ants stir the soil and aerate it, allowing water and oxygen to reach the roots of plants.

Question 5) What is the study of the interaction between the various microorganisms present in the soil and biotic and abiotic components of the soil environment known as?

a. Soil ecology
b. Ecology
c. Microbiology
d. Soil ecosystem
Answer- Option a.

Explanation- Soil ecology is the study of how diverse microorganisms in the soil interact with biotic and abiotic elements of the soil environment.

Common mistakes

Students frequently mix up the terms soil ecosystem and ecosystem. An ecosystem is made up of all living and non-living species found in a certain natural area. The most prevalent ecosystems are forests, grasslands, deserts, tundra, freshwater, and marine ecosystems. The soil ecosystem, on the other hand, has a significant impact on the health of all ecosystems.

Related Topics

• Soil science
• Soil chemistry
• Soil biology
• Soil ecosystem services