Topsoil is the upper, outermost layer of soil, usually the top 5–10 inches (13–25 cm). It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.
Topsoil is ideal for filling in low spots in lawns or along walks and patios. Adding a few inches of topsoil gives lawn grass a better chance than subsoil or clay. When planting trees and shrubs, replacing the existing soil with topsoil can help plants grow better.
Limestone has numerous uses: as a building material, an essential component of concrete (Portland cement), as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, as a chemical feedstock for the production of lime, as a soil conditioner, and as a popular decorative