Which layer consists of decomposing plant parts at the soil surface of turfgrass?

The correct choice relates to thatch, which is a layer of organic material that accumulates on the soil surface of turfgrass as a result of the buildup of decomposing plant parts, such as grass clippings and root debris. Thatch plays a vital role in the health of turf because it can influence moisture retention, soil temperature, and overall soil fertility. If thatch becomes too thick, it can prevent water and nutrients from penetrating to the soil below, potentially leading to turf health issues.

In contrast, topsoil is the uppermost layer of the soil profile that contains a mixture of organic matter, minerals, and nutrients, but it is not specifically the decomposing plant matter at the surface. Humus is well-decomposed organic material that enriches soil and improves its structure but is found deeper in the soil profile rather than at the surface. Compost refers to organic matter that has been processed to create a product that can enhance soil fertility but is not inherently the same as thatch.