Agriculture Reference
In-Depth Information
thus increased oxidative conditions. The use of adjectives such as “strong” in
describing soil structure such as in the soil profile descriptions in Figures 1.1
and 1.5 indicates ped formation that is strong enough to resist breakdown
under wet conditions, thus leading to pores that drain well even when wet.
Strong structure favors oxidation of soil constituents as long as the soil does
not have a high water table.
1.7.
CONCLUSIONS
Soils develop by the action of the soil forming factors on soil parent materi-
als, including material transported by different agents. The result of these soil
forming factors is the formation of soil horizons, different colors, and peds.
Each of these factors has a pronounced effect on a soil's chemistry. Knowl-
edge of the soil type and profile description can provide the soil chemist,
analyst, or researcher with valuable information about the characteristics of
soil relevant to the development of extraction, analytical, and instrumental
analytical procedures. It also is the place to start when investigating the failure
of a procedure.
PROBLEMS
1.1.
Describe how horizons form in soil. How would knowing the horizon
help a soil chemist understand differences in extractability of a soil
component?
1.2.
List three major horizon designations and three subordination designa-
tions and explain what information they reveal about the horizon.
1.3.
What common soil characteristics are indicated by soil color? Explain
how a soil's color is described.
1.4.
Name two major different types of soil structure. How does soil structure
relate to a soil's oxidative or reductive conditions?
1.5.
Which major soil types have high salt and pH levels? Which have low
levels?
1.6.
Describe the effect of small pores on the chemistry of a soil and what
types of compounds are likely to be found.
BIBLIOGRAPHY
Bradey NC, Weil RR.
The Nature and Properties of Soils
, 12th ed. Upper Saddle River,
NJ: Prentice-Hall, 1999.
Dent D, Young A.
Soil Survey and Land Evaluation
. Boston: George Allen & Unwin,
1981.
