Decaying organic material creates which soil component?

• A. Loam
• B. Clay
• C. Humus
• D. Limestone

Answer: (C)

Decaying organic material creates humus, the stable organic matter that remains in soil after decomposition. Microbes breakdown plant and animal residues and, through humification, transform them into humus. This material is intimately bound to mineral particles, giving soil better structure, more porosity, and greater water and nutrient retention. Humus isn’t a mineral particle like loam, clay, or limestone; loam is a balanced mix of mineral particles, clay is a fine mineral component, and limestone is a carbonate rock. Humus is the organic component that results from decomposition and is key to soil fertility.