Download Bulk density

Unit
BULK DENSITY
OF SOIL
Objectives
1. Describe the concept and importance
of soil density.
2. Determine soil density.
3. Explain how to alter soil density.
4. Describe the effect of soil density on
erosion, water holding capacity and
flooding.
Terms
Bulk density
Consistence
Particle density
Structure
Texture
Describe the concept and
importance of soil density.
What is bulk density?
- Bulk density is a measurement
of how tightly soil particles are
pressed together.
- Density is the mass of an object
divided by the volume.
Bulk density
- Texture, the relative proportion of
soil separates in a soil, affects the
density, as different separates have
different masses and have
corresponding pore space.
Structure
- the arrangement of soil particles
into aggregates or peds, also
determines density because
various soil arrangements will
compact more easily than others.
Particle Density
- of the soil is the mass per unit
volume of soil particles
excluding the pore space.
-The soil consistence,
the soil’s response to pressure at
various moisture levels, can be
described as hardness, friability,
stickiness, and plasticity.
Determine soil density.
How can you determine soil
density?
- Soil density is the mass of
the soil particles divided by
volume.
- When removed from the earth’s crust
the soil contains air and water that will
affect the mass readings and do not
constitute soil density.
- The soil needs to be dried in
order to find the true density.
- Density is usually expressed in
grams per cubic centimeter.
Explain how to alter soil
density.
How can you change soil density?
- Soil density is affected by
tillage and non-tillage
systems.
- The working of the subsoil by a
subsoil tillage system can decrease
the density of the soil by encouraging
more pore space per volume.
B. Some seedbeds and fields have
too little soil density so rolling the
field or working the soil with a
finisher may provide better
seedbed density.
- At construction sites it is
important to have a compacted
subsoil so settling will not occur
once the building is completed.
Describe the effect of soil
density on erosion, water
holding capacity, and flooding.
What effect does soil density have
on various soil characteristics?
IV. Soil density affects soil
characteristics.
A. With higher the soil density the
amount of pore space decreases,
thus decreasing the water holding
capacity of the soil. This decrease in
water holding capacity is especially
significant in the larger pore spaces
that are readily available to hold water
which plants can utilize.
Erosion
-can also be affected by density,
as water will not infiltrate the soil
as readily
-will stay in contact with the topsoil
for a longer period of time.
Flooding
-Flooding will result from excessive
runoff and decreased infiltration in wet
years.
-Puddling can result from localized
compaction, as is the case in tractor tire
ruts.
Bulk Density Equation.
Bulk density =
oven - dry weight in grams
volume of cylinder in
cubic centimeters