Question

Decomposing matter in soil is called a. clay c. silt b. humus d. sand

Short answer

b. Humus

Step-by-step solution

Identify Key Terms

Identify the key term in the question which is 'Decomposing matter in soil.' This term refers to the organic component of soil formed by the decomposition of leaves and other plant material by soil microorganisms.

Understand Options

Understand each option provided in relation to soil: - a. Clay: A type of fine-grained natural soil material. - b. Humus: The organic component of soil, formed by the decomposition of plant material. - c. Silt: A granular material between sand and clay in size. - d. Sand: Large, coarse particles of soil.

Match Key Term to Correct Option

Match the key term 'Decomposing matter in soil' to the correct option. 'Humus' is the term that matches as it is formed by the decomposition process in soil, unlike clay, silt, or sand, which are mineral components.

Key concepts

Decomposition

Decomposition is an essential natural process in which organic substances are broken down into simpler organic or inorganic matter. This process is predominantly carried out by microorganisms, including bacteria and fungi, which play a vital role in recycling nutrients.
During decomposition, materials such as leaves, wood, and dead organisms are transformed. This transformation is crucial for the sustainability of ecosystems, as it allows for the release and recycling of essential nutrients like nitrogen and phosphorus.

• Role of Decomposition: It assists in reducing dead matter, thus maintaining the cycle of energy and nutrients in nature.

Without decomposition, the world would be overrun with organic waste, and nutrients would be locked away in dead organisms, unavailable to living plants and animals.

Humus

Humus is the rich, dark organic material formed in soil when plant and animal matter decays. It is an essential component of soil that significantly contributes to its fertility and structure.
This spongy material is a key element of topsoil, supplying plants with crucial nutrients and enhancing water retention and air permeability.

• Benefits of Humus: Improving soil structure and fertility.
• Nutrient Supply: Releasing nutrients over time, allowing plants to absorb them efficiently.
• Water Retention: Its ability to hold moisture benefits plant growth, particularly in drier climates.

Overall, humus is vital because it maintains soil health and productivity, supporting sustainable plant life.

Soil Microorganisms

Soil microorganisms are microscopic organisms living in the soil. They are fundamental to the process of decomposition and nutrient cycling, making them indispensable to ecosystem health.
These microorganisms include bacteria, fungi, protozoa, and some algae. Bacteria and fungi are the most active in breaking down dead organic matter, a process that directs the flow of nutrients through the ecosystem.

• Role of Bacteria: They decompose organic material and fix nitrogen from the atmosphere, making it available to plants.
• Role of Fungi: They help decompose complex organic substances, such as cellulose and lignin, which are found in wood and plant fibers.
• Protozoa and Algae: While less involved in decomposition, they play roles in nutrient cycling and forming soil structure.

These microorganisms ensure the availability of nutrients necessary for plant growth and have a profound impact on soil fertility and health.