Soil

1. types

1.1. desert

1.1.1. grassland

1.1.1.1. forest

1.1.1.1.1. tropical grassland

2. 3 main things in the soil

2.1. nitrogen

2.1.1. phosphorus

2.1.1.1. potassium

3. is made of

3.1. weathered rocks

3.1.1. sand

3.1.2. silt

3.1.3. clay

3.2. organic matter

3.2.1. definition

3.2.1.1. Decomposed material that goes into soil

3.3. made of

3.3.1. nutrients

4. layers

4.1. topsoil

4.1.1. subsoil

4.1.1.1. parent material

4.1.1.1.1. bedrock