|The decayed remains of dead plants and animals in soil.
|The layer of bits of rocks and humus found on Earth's crust.
|A type of soil with very small grains and small spaces between them.
|The top layer of soil.
|Rich soil with lots of humus.
|A material found in nature that living things use.
|Saving resources by using them carefully.
|Planting strips of different crops next to each other.
|Planting rows of crops around hills instead of up and down their sides.