32
WALLACE H. FULLER
E. Micronutrients
66
F. Organic Matter
67
G. Salt
69
H. Radioactive Debris
71
VIII. Desert Soils and Microorganisms
71
A. Microbial Populations
71
B. Nitrogen Fixation and Transformation
73
C. Algae
73
D. Protozoa
75
E. Actinomycetes
75
F. Fungi
75
G. Specialized Organisms
76
IX. Soils of Individual World Deserts
77
A. Kalahari-Namib
77
B. Sahara
78
C. Somali-Chalbi
79
D. Arabian
80
E. Iranian
81
F. Thar
82
G. West Central Asia-Turkestan
83
H. Central Asia—Takla-Makan
84
I. East Central Asia—Gobi
85
J. Australian
86
K. Monte-Patagonian
88
L. Atacama-Peruvian
88
M. North American
89
X. Concluding Statement
93
References
94
In the desert path,
Raising puffs of alkali dust—
The roadrunner's bath.
W. H. Fuller, Roadrunner
I. Introduction
Through the action of physical, chemical, and biological agents of
weathering, parent geological materials are synthesized into soils with time.
Thus soils are a "genetic" product of their environment and represent a synthesizing living body as opposed to mere physical accumulation of degraded
material. Not all of the thin veneer of unconsolidated earth crust, however,
is considered to be soil, since some surface materials may not be developed
significantly from what they were when originally exposed or subdivided
in place or transported and deposited. Certain desert areas are characterized by surfaces on which well-developed soils have not formed. For exam-