Texas FFA Nursery Landscape Practice Exam

A layer of partially decomposed stems, roots, and leaves of grass that develops above the soil's surface in the lawn is called?

1. Mulch

2. Thatch

3. Inorganic matter

4. Mineral matter

The correct answer is: Thatch

The correct answer is thatch, which refers specifically to the layer of partially decomposed organic material that accumulates on the surface of the soil in a lawn. Thatch consists mainly of grass stems, roots, and leaves that are not fully decomposed. While a certain amount of thatch can be beneficial, providing nutrients and protecting the soil, excessive thatch can lead to problems such as limiting water and nutrient absorption by the grass. Mulch, while similar in being made of organic materials, is typically applied to the surface of the soil intentionally by gardeners to suppress weeds, retain moisture, and enhance soil health, rather than being a natural accumulation like thatch. Inorganic matter refers to non-organic components found in soil, such as sand, silt, and clay, which do not include decomposed plant material. Mineral matter is a broader term that encompasses all of the inorganic components in the soil, making it distinct from the organic nature of thatch. Thus, thatch is the term that captures the specific nature and characteristics of the layer mentioned in the question.