topsoil

Everyday

Topsoil is the top layer of soil, usually dark, rich and full of nutrients, where most plants grow their roots. tree →

In the lessons

In science and geography lessons, topsoil lies over subsoil and rock; it contains humus from rotting plants, worms and tiny living things. Farmers and gardeners protect topsoil because wind and rain can wash it away (erosion). Phrases: a layer of topsoil, topsoil erosion, buy topsoil.

Examples

• Most plants grow their roots in the topsoil. tree →
• Worms mix rotting leaves into the topsoil. tree →
• Heavy rain can wash away the topsoil. tree →
• We bought 3 bags of topsoil for the vegetable patch. tree →
• Topsoil is darker than the subsoil below it. tree →
• Trees help stop the topsoil from blowing away. tree →
• It can take hundreds of years to form a few centimetres of topsoil. tree →

Note

Uncountable noun: «some topsoil», «a bag of topsoil». One word. The layer below is «subsoil», then «bedrock».