Exam 12: Soils

Soil structure is usually determined by clumps called ________.

Organic material generally comprises less than 5 percent of the total soil volume.

Which of the following is NOT true of soil air?

Soil is considered to include dead and decaying organic matter.

The A horizon or combined O/A horizons of the soil are known as the ________.

The highest rated soils for overall agricultural productivity are the ________.

Oxisols are common in the tropics and occur in Hawaii but are absent from the rest of the United States.

A dense layer, often forming in the B horizon under calcification is ________.

The soils characterized by plentiful partly decayed plant material are ________.

________ is a measure of the ease with which water moves through the soil.

The deposition of finer particles at a lower level in the soil is illuviation.

Three-quarters of the soil's metabolic activity is generated by ________.

Spodosols are among the most fertile soils on the Earth.

The unconsolidated parent material beyond the reach of most roots is ________.

Of the following, which covers the least area on Earth's surface?

The existence of a B horizon is an indication of a(n) ________ soil.

Soil water is sometimes added to from the groundwater.

Permafrost and minimal profile development are most closely associated with which soil order?

The ________ is a diagram commonly used to illustrate the relative percentages of sand, silt, and clay in soil.

Humus is associated with ________.