page11
11
Soil physical characteristics often dictate
the success or failure of an agricultural
project. If you do not work within the
physical characteristics of the soil, you
will find yourself fighting an uphill battle.
Management practices can help improve
desirable soil physical characteristics, such as
robust soil structure and ideal bulk densities,
but they can also have negative impacts on
a soil’s profile, such as creating a restrictive
layer that prevents water movement. Lastly,
management practices are unable to change
inherent physical characteristics, such as
texture; it is always necessary to work with
rather than against inherent characteristics
to ensure soil health improvements and the
success of agricultural operations.
Soil physical characteristics are often
likened to the building materials of a house,
which are put together to form its walls and
rooms, and overall architectural structure.
Analogously, soil physical characteristics
form “soil architecture.”
Brady & Weil, 2010
Soil texture and structure together give soil
its ability to convey water and air, hold soil
nutrients, and provide the space in which soil
chemistry and soil biology occur.
After completing this section
you will be able to:
•
Distinguish which soil characteristics
can and cannot change, based on
management of a given area within
a given amount of time
•
Describe the processes by which soil
is formed and lost
•
Describe how soil texture, structure,
and bulk density affect soil functions
•
Determine texture by settlement
and by the feel method
•
Determine soil bulk density
•
Compare water stable aggregates
from different soil types and
management regimes
•
Describe what impacts soil organic
matter has on soil structure
•
Describe how water is held and
flows within a soil and with respect
to plant availability
Learning Outcomes
2.1 Physical Characteristics
2. Soil Fundamentals