Soil Orders
This unit is comprised of two or more pedons.
Polypedon
If the SBD is the same between a sandy soil and a clay soil, this one is easier for roots to penetrate through.
Sandy
Soil with high pore space have this level of bulk density.
Low bulk density (less particles mean less weight).
The part of the soil that is not the organic fraction is what?
Mineral fraction
This is a macropore created by roots, earthworms or other organisms.
Aerobic decomposition occurs in the presence of what? So then, what is anaerobic decomposition?
There are this many soil orders.
12
This is the mass per unit volume of soil solids (and does not include pore space).
Particle density
These are the ideal proportions (%) of a solid, liquid and gas phases in a soil.
50% solid, 25% liquid, 25% gas
These three elements are the building blocks of all carbohydrates.
Carbon, Hydrogen, Oxygen
This plant tissue decomposes most quickly.
Glucose (sugar/carbs) as opposed to cellulose or lignin.
This type of organism breaks down dead tree material fastest.
Fungi, saprophytic fungi
What are the two most prominent soil orders found in Texas?
Mollisols and Vertisols
This is the total mass per volume of soil.
Soil bulk density.
Dense or brittle pan subsurface layer that owes its hardness mainly to extreme density or compactness rather than high clay content.
Fragipan
An autotroph performs this function.
This plant tissue takes the longest to decompose.
Lignin
This is the original source of soil organic matter.
Plant tissue
This is the upper part of the soil, darkened by organic matter, the upper eluvial horizons, or both.
Epiphedon.
These are two factors that affect the ability for plant roots to penetrate the soil.
What is soil water content, soil texture or land use management.
Name the two types of soil compaction
Surface compaction and Subsurface compaction.
SOM has this effect of soil compaction.
resists soil compaction, "spongy" material
These are two reasons that residues incorporated into the soil decompose faster than residues sitting on the surface.
They are within the reach of most soil organisms, they are not subject to moisture or extreme temperatures.
This is the reason that CO2 is present in higher proportions in the soil than above the soil
Aerobic organisms exhale CO2 as they break down carbon sources within the soil and it becomes trapped there.
Green plant tissue above ground lowers CO2 and adds O2.
This soil order has high shrink-swell properties, which form cracks in the soil surface into which water and other granules collect to essentially invert the soil (also known as a 24 hour soil).
Vertisols
Describe how long term, intense tillage, affects soil bulk density and why.
Creates micropores from compaction and breaking up of soil aggregates.
These are three reasons that soils located deep in the soil profile have a high bulk density.
Low SOM, less aggregation, fewer roots and other soil dwelling organisms, compaction cause by weight of overlying soil layers
These are three contributions SOM gives to the health of a soil.
These are the two basic steps of enzymatic degradation.
Long chains are broken into shorter chains by specialized organisms, then into individual glucose molecules.
WILDCARD: A loam is defined as a mixture of sand, silt and clay particles that exhibit the properties of those separates in nearly equal proportions. Does this mean that the sand, silt and clay effects are present in nearly equal amounts? Why or why not?
Clay has very dominant characteristics, so even a small amount in the soil will exhibit the properties of clay over sand and silt.