Soil Formation

solid layer of rock beneath the soil; once exposed bedrock gradually weathers in smaller particles that are the basic material of soil

• bedrock

• soil

• topsoil

• horizon

dark colored substance in soil from decayed organic material

• bedrock

• topsoil

• humus

• C horizon

measure of how well soil supports plant growth

• topsoil

• humus

• plant health scale

• fertility

soil that is made up of equal parts of clay, sand, and silt best for growing most types of plants

• decomposers

• organic

• soil

• loam

the "A" horizon or the op layer is crumbly, dark brown mixture of humus, clay and other material

• subsoil

• soil horizon

• topsoil

• "C" horizon

farmers plow their fields along the curves of the slope to help slow runoff of excess rainfall, which may wash away the soil

• contour plowing

• conservation plowing

• crop rotation

• soil

farmers leave dead weeds and stalks of previous year's crops to all return nutrients to the soil, retain moisture and hold the soil in place

• contour plowing

• conservation plowing

• crop rotation

farmer plants different crops in a field each year

• contour plowing

• conservation plowing

• crop rotation