Question

why is top of soil more useful to us?

Answer 1

Topsoil is the upper, outermost layer of soil, usually the top 5 inches (13 cm) to 10 inches (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 composed of mineral particles, organic matter, water, and air. Organic matter varies in quantity on different soils. The strength of soil structure decreases with the presence of organic matter, creating weak bearing capacities. Organic matter condenses and settles in different ways under certain conditions, such as roadbeds and foundations. The structure becomes affected once the soil is dewatered. The soil's volume substantially decreases. It decomposes and suffers wind erosion.[1]

Answer 2

Importance. Plants generally concentrate their roots in and obtainmost of their vital nutrients from this layer. Actual depth of the topsoil layer can be measured as the depth from the surface to the first densely packedsoil layer known as subsoil.