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2.2 Chemical Characteristics
After completing this section
you will be able to:
•
Describe where soil pH comes from
and how it affects soils in New Mexico
and Colorado
•
Describe the nutrients essential for a
productive soil
•
Discuss how soil pH interacts with
nutrient availability
•
Understand the C:N (carbon to
nitrogen) ratio and what it means for
soil productivity
•
Describe where salts in soils come
from and the difference between
salinity and sodicity
Chemical characteristics include the ways
that different compounds in the soil react
with each other and cycle in and out of the
system. For example, you will learn that pH
can affect how easily a plant can access some
kinds of nutrients and thus be either well-
fertilized or deficient. Different conditions can
lead either to compounds dissolving in water
and washing away or to their accumulating as
solids in the soil, for example as a salt crust.
Chemical characteristics are tightly related to
the activity of living organisms. The building
blocks of life are primarily the elements
carbon, nitrogen, oxygen, hydrogen, sulfur
and phosphorus. In cells, these compounds
form molecules of proteins (structure and
metabolism), carbohydrates (structure and
energy), fats (energy and signaling), and
nucleic acids (genetic information). When
combined to form living organisms, chemicals
become biological. Microbial activity is
essential for breaking down and processing
raw or decomposing materials into forms
usable by other life forms, which we will
discuss further in the biological characteristics
section (page 51). Understanding the
availability of the different chemical elements
and compounds in soil is essential to
understanding soil productivity.
Learning Outcomes