Which of the following is NOT a type of mulch?

The correct answer is that plastic sheets are not considered a type of mulch. Mulch is generally defined as a layer of material spread over the surface of the soil to retain moisture, suppress weeds, and enhance the aesthetic appeal of a garden or landscape.

Wood fiber, paper fiber, and straw/hay are all organic or fibrous materials that fit the definition of mulch. They decompose over time, enriching the soil with organic matter. Additionally, these materials contribute to moisture retention and help regulate soil temperature, further benefiting plant health.

In contrast, plastic sheets serve a different function. They are typically used for weed control and soil temperature regulation by creating a barrier that prevents water infiltration and maintains moisture levels below the sheet. Although they can suppress weeds and manage soil temperatures, they do not enrich the soil like organic mulches do. Therefore, plastic sheets do not meet the criteria to be classified as mulch, making them the correct choice in this context.