OBJECTIVE FORESTRY

Detailed explanation-1: -It is a process in which the top fertile layer of soil is lost. Due to soil erosion, the soil becomes less fertile. The top layer of soil is very light which is easily carried away by wind and water. The removal of topsoil by the natural forces is known as soil erosion.

Detailed explanation-2: -The surface soil, or topsoil layer (O and A horizon in Figure 1–2), usually contains less clay, but more organic matter and air, than the lower soil layers. Topsoil is usually more fertile than the other layers and has the greatest concentration of plant roots.

Detailed explanation-3: -Topsoil contains large amounts of organic matter due to its high concentration of dead plants, leaves, dead insects, fungi, and high numbers of microorganisms. Most topsoil is a mixture of sand, silt, clay, and humus (decomposed leaves, plants, twigs, insects, and other organisms).

Detailed explanation-4: -Soil is usually layered. The uppermost layer is called topsoil and this layer contains humus, plant roots, and living creatures. The more humus found in topsoil, the more nutrient rich the topsoil and the better the conditions for growing plants. The middle layer is called subsoil.