Exam 15: Global Soils

The key factor in determining how the soils of a region support vegetation and crops is the:

Define humus, explain where it is found, and explain how it affects soil color.

The alteration of material within soil layers is called:

The alfisols have a low base status.

Accumulation in a lower soil layer of materials brought down from upper layers is:

On the illustration, the soil at O is:

The proportion of particle sizes that make up the soil is its structure.

Prairie soils are usually ash-gray in color.

The soil type without horizon development is the:

Explain how soil texture is determined and named.

The descriptive property of the mineral portion of soil based on varying proportions of sand, silt, and clay is the soil:

The inorganic material base from which soil forms is called:

The temperature at which most root growth and germination begins is:

On the illustration, the letter that represents silt-sized particles is:

Adding organic and inorganic matter to the soil is:

The fertility of the soilwater solution for plants is based on the ability of the soil to hold and exchange cations, which is called:

The number of soil orders used in the United States Soil Conservation System as presented in this text is:

Distinctive layers of soil, roughly horizontal, set apart from other layers by differences in physical or chemical composition are called:

A high humus content makes soil appear:

The finely divided, partially decomposed organic matter in the soil is called: