| A | B |
|---|
| Soil | loose, weathered material on Earth's surface in which plants can grow. |
| Bedrock | solid layer of rock beneath the soil |
| Humus | dark-colored substance that forms as plant and animal remains decay |
| Soil is a mixture of: | rock particles, minerals, decayed organic material, water, and air |
| Where do minerals in soil come from? | weathering of rock since rocks are made up of minerals |
| fertility | soil is a measure of how well the soil supports plant growth |
| loam | Soil that is made up of equal parts of clay, sand, and silt |
| Best soil for growing plants | Loam |
| pH scale | meansures acidity |
| soil horizon | layer of soil that differs in color, texture, and composition from the layers above or below it |
| topsoil | crumbly, dark brown soil that is a mixture of humus, clay and other minerals |
| subsoil | clay and other particles of rock but has little humus |
| decomposers | the organisms that break the remains of dead organisms into smaller pieces and digest them with chemicals |
