Certified Crop Advisor Practice Exam

The stable form of soil organic matter is called?

1. Peat

2. Humus

3. Litter

4. Compost

The correct answer is: Humus

Humus refers to the stable form of soil organic matter that results from the decomposition of plant and animal material. Over time, as organic matter breaks down, it undergoes various processes that transform it into humus, which is dark, rich, and provides numerous benefits to soil health. This stable form helps improve soil structure, enhances moisture retention, and increases nutrient availability, making it vital for supporting plant life. Peat, litter, and compost represent different stages or types of organic matter. Peat is an accumulation of partially decayed plant material typical in wetland environments, while litter consists of fresh leaves, twigs, and other organic debris on the soil surface that has yet to decompose significantly. Compost is a controlled process of decomposing organic waste that is often used as a soil amendment but is not the stabilized end product like humus. Therefore, humus stands out as the essential, stable form of soil organic matter crucial for soil function and fertility.