What is soil erosion?

Soil erosion refers to the removal of the topsoil layer, which is the uppermost layer of soil rich in organic matter and nutrients essential for plant growth. This process can occur due to various factors, including water, wind, and human activities such as farming and construction. The topsoil is critical because it contains the majority of soil's biological and chemical activity that supports vegetation. When this layer is eroded, the land becomes less productive, leading to decreased agricultural yields and affected ecosystems.

The other options do not correctly define soil erosion. The natural formation of soil layers describes soil development over time, while the process of soil becoming more fertile refers to the accumulation of nutrients and organic materials, which contrasts with the degradation caused by erosion. The washing away of nutrients may be a consequence of erosion, but it does not fully encompass the primary concept of soil erosion itself. Overall, understanding soil erosion is vital for effective land management and conservation practices.