Soil Geography /Global Distribution Of Soils

In this module, you will identify and explain the geographic distribution, patterns, and processes associated with Earth’s soils.

Note: Please refer to the GETTING STARTED lab module to learn tips on how to set up and maneuver through the Google Earth ( ) component of this lab.

KEY TERMS

The following is a list of important words and concepts used in this lab module:

Cation-exchange capacity (CEC)

Particle size –sand, silt, clay

Soil profile

CLORPT

Pedogenic processes

Soil structure

Diagnostic horizon

Pore space

Soil solution

Eluviation

Soil color – hue, value, chroma

Soil Taxonomy

Humus

Soil consistence

Soil texture

Illuviation

Soil horizons – O, A, E, B, C, R

Transpiration

Inorganic material (matter)

Soil moisture

Organic material (matter)

Soil pH

LAB MODULES LEARNING OBJECTIVES

After successfully completing this module, you should be able to:

· Identify the fundamental components of soil

· Explain the factors that influence the development of soil (CLORPT)

· Identify soil orders and soil series by diagnostic characteristics and location

· Explain soil profiles and soil horizons

· Recognize soils by texture and color

· Describe the geography of soils at various taxonomic levels

INTRODUCTION

This module examines the geography of soil. Topics include soil classifications, soil horizons, soil moisture, pH and color. While these topics may appear to be disparate, you will learn how they are inherently related.

The modules start with five opening topics, or vignettes, which are found in the accompanying Google Earth file. These vignettes introduce basic concepts of the geography of soil. Some of the vignettes have animations, videos, or short articles that will provide another perspective or visual explanation for the topic at hand. After reading the vignette and associated links, answer the following questions. Please note that some components of this lab may take a while to download or open, especially if you have a slow internet connection.

Expand SOIL GEOGRAPHY and then expand the INTRODUCTION folder.

Read Topic 1: The Earth’s Soils.

Question 1: Looking at the map, what is the soil moisture terminology used for regions with relatively humid climates and well-distributed rainfall, where water moves down through the soil via soil pores, like that of eastern USA, the United Kingdom, Norway, and eastern China?

a. Udic

b. Aridic

c. Ustic

d. Perudic

Read Topic 2: Soil Forming Factors

Question 2: Which factor – climate, organisms, relief, parent material, or time – would affect most universally the soils in mountainous areas?

a. climate

b. organisms

c. relief

d. parent material

e. time

Read Topic 3: Soil Characteristics

Question 3: How are colloids beneficial to plants (Hint: What can they do that helps plants)?

a. Colloids dissolve soil water for plant use

b. Colloids contain acid ions that leach nutrients from soil

c. Colloids harbor positively charged surfaces to attract nutrients

d. Colloids hold soil nutrients for plant use

Read Topic 4: Soil Horizons

Question 4: The photo image shows a massive horizon of accumulated clays, oxides, and organics. Does this soil profile show a massive O horizon, A horizon, E horizon, B horizon, or C horizon?

a. 0 horizon

b. A horizon

c. E horizon

d. B horizon

e. C horizon

Read Topic 5: Soil Degradation

Question 5: Reading the map, what is the global status of soil in South Africa, the internal region of Madagascar, and the majority of eastern China?

a. Very high severity

b. High severity

c. Moderate severity

d. Low severity

Collapse and uncheck INTRODUCTION

GLOBAL PERSPECTIVE

In this section, you will identify how soils are distributed at a global scale. Remember, scale is an important concept in geography, because some patterns can be seen only at the global (coarse) scale and not at the local (fine) scale.

Expand GLOBAL PERSPECTIVE and then click and select, Soil Taxonomy Map.

Soils are generally classified using their soil profiles and other physical, chemical, and biological characteristics. How they are classified, or grouped into categories, depends on the classification system used. There are many recognized soil classification systems in the world, including classification systems from Canada, Russia, China, Germany, Australia, the United States, and the internationally recognized FAO World Reference Base for Soil Resources (WRB). For this section, the soil order nomenclature (how soils are named) is based on the United States classification system known as the USDA Soil Taxonomy. The resultant map overlay shows particular geographic patterns of soil with climate and relief that are evident at the global scale.