Exam 12: Soils

Explain cation exchange.

The most weathered and leached of all soils are the ________.

Which is NOT a main soil-forming factors?

The presence of humus in the soil lowers the density of the soil.

Most soil development takes place ________.

The productive wheat lands of parts of Washington, Oregon, and Idaho are underlain by soils incorporating volcanic ash and classified as ________.

Which of the following NOT a reason earthworms increase the fertility of the soils in which they reside?

Mollisols are relatively rare soils in the United States.

What can be learned from a soil triangle?

The unconsolidated parent materials beneath the level of roots is called the ________ horizon of soil.

Histosols are a soil order most common in world deserts.

On the standard pH scale, the number 10 indicates a ________ soil.

Globally, the influence of this soil-forming factor fades with time.

The measure of a soil's capacity to hold water and air is called ________.

The shallowest soils can be found in which regions?

________ is least available to plants because it is held in chemical combination with the minerals in the soil.

Mollisols and ________ are the two most agriculturally productive soil orders.

Which of the following is NOT true of soil air?

In semiarid climates, grass roots transport much ________ from the B horizon to the A horizon.

Briefly describe each of 5 of the 6 possible soil horizons.