6.E.2 Soil

What is the source of organic material needed for most fertile soils?

• moving water

• eroded sand

• decaying plants

• weathered bedrock

The composition of soil influences the soil's ability to retain and transmit water and air. What soil type would be best for planting a productive garden?

• Sandy soils because they provide high silica content.

• Loamy soils because they contain sand and clay.

• Slightly rocky soils because they provide needed materials.

• Clay soils because they are heavy soils and repair water.

When microorganisms deplete the oxygen in soil through respiration, the soil becomes

• humus

• anaerobic

• compost

• aerobic

The iron in iron-rich red soils may not be in a form that can be taken up by tree roots. As a result, leaves and needles may look yellow. Some trees release acids that convert iron in soil to a usable form. The change in soil chemistry is a type of which process?

• deposition

• weathering

• precipitation

• photosynthesis

Humus is an organic material that makes up soil. Which characteristic best indicates that soil has a high humus content?

• the color of the sample

• the mass of the sample

• the amount of the clay in the sample

• the amount of rock in the sample

The finest grained soils are richest in

• sand

• humus

• clay

• iron

How cam the type of bedrock under soil affect the characteristics of the soil?

• by preventing soil erosion

• by absorbing excessive rainwater

• by contributing small rock particles to the soil

• by providing surface area for nutrient accumulation

Which is an example of a mixture?

• oxygen

• ice

• soil

• silver

Which is considered a property of soil?

• streak

• fracture

• texture

• luster

What should be added to soil to increase its water retention?

• pebbles

• sand

• rocks

• clay