What is Soil & how many types of soil is out there? Meaning and definition -Soil is a thin upper layer of material on the Earth's surface where plants have their roots. It is made over a long period of time with weathered rocks and decayed plants and animals.A scientist who studies the soil is known as pedologist. There are three (3) major types of soil -Sandy,Clay and Loam . As for as soil profile is concerned, soil is made of different layers, these layers of soil are called soil horizons.Each layer has its own distinct characteristics.The upper layers are rich in organic matter,humus and other nutrients and are good for plants.The lower layers are rocky.Upper layer is called topsoil whereas lower level layers are known as subsoil and bedrock.