SCSC 301 TAMU Exam 2 Howe(100%
Correct!!)
Which of the following is NOT a carbon-containing compound that is involved in the cycling of carbon
associated with most plant/animal life forms? - ANSWERCalcium carbonate
Which organic matter property affects the availability of nutrients to plants? - ANSWERCation
exchange capacity
Complete degradation of residues (complete oxidation) results in - ANSWERCO2
Which of the answers below represents an immobilized form of N? - ANSWERProtein in a bacterial
cell
Which is true when comparing aerobic vs anaerobic organic matter decomposition? -
ANSWERAnaerobic degradation is much slower than aerobic and results in compounds that are
partially decomposed
Soil organic matter degradation will be greatest when - ANSWERThere is sufficient soil moisture and
aeration at neutral pH and relatively warm temperatures to degrade residue with high levels of N
Organic matter tends to decrease the ___ of soils. - ANSWERBulk density
___ is the element in residue that has the greatest effect on the rate of residue decomposition. -
ANSWERNitrogen
The organic matter content of soils tends to decrease with increasing frequency of: -
ANSWERCultivation
If you had to guess, which environment would likely have the greatest soil organic matter? -
ANSWERNortheast US
Available water in soils is water held between the wilting coefficient and - ANSWERField capacity
, Water that drains downward in a soil consists of water moving in response to differences in -
ANSWERPrimarily gravitational potentials
Water enters a very clayey subsoil from a sandy surface soil - ANSWERAs soon as the wetting front
reaches it
In a soil containing large holes or channels that are closed at the surface, water enters these large
holes - ANSWERonly after the surrounding soil is saturated
A soil with C/N ratio of 600:1 could be a material such as - ANSWERSawdust or leaves that have a low
N content and a high potential for N immobilization
Poorly defined organic substances that are complex, resistant to decay, and polymeric are -
ANSWERHumic substances
Which of the following could be used to improve soil organic matter in a cropping system? -
ANSWERReduce the plant materials that are harvested and return any residues back to the field
Water moves downward in a profile from the B horizon (clay loam) into gravel layer - ANSWEROnly
after the B horizon is saturated
As water is adsorbed by a dry soil, the soil matric potential of the dry soil - ANSWERIncreases
Water moves downward in a profile from the A horizon (sandy loam) to the B horizon (loam) -
ANSWERAs soon as the wetting front reaches the B horizon
Evaporation losses of water from soils may be reduced by - ANSWERCrop residue on the surface
Water is moving upward from an aquifer. The surface is clayey and the subsurface is a mix of coarse
sand and gravel. Which is true about movement of water from the coarse-textured subsurface to the
fine-textured surface? - ANSWERWater will not move from the coarse texture until it is saturated
Correct!!)
Which of the following is NOT a carbon-containing compound that is involved in the cycling of carbon
associated with most plant/animal life forms? - ANSWERCalcium carbonate
Which organic matter property affects the availability of nutrients to plants? - ANSWERCation
exchange capacity
Complete degradation of residues (complete oxidation) results in - ANSWERCO2
Which of the answers below represents an immobilized form of N? - ANSWERProtein in a bacterial
cell
Which is true when comparing aerobic vs anaerobic organic matter decomposition? -
ANSWERAnaerobic degradation is much slower than aerobic and results in compounds that are
partially decomposed
Soil organic matter degradation will be greatest when - ANSWERThere is sufficient soil moisture and
aeration at neutral pH and relatively warm temperatures to degrade residue with high levels of N
Organic matter tends to decrease the ___ of soils. - ANSWERBulk density
___ is the element in residue that has the greatest effect on the rate of residue decomposition. -
ANSWERNitrogen
The organic matter content of soils tends to decrease with increasing frequency of: -
ANSWERCultivation
If you had to guess, which environment would likely have the greatest soil organic matter? -
ANSWERNortheast US
Available water in soils is water held between the wilting coefficient and - ANSWERField capacity
, Water that drains downward in a soil consists of water moving in response to differences in -
ANSWERPrimarily gravitational potentials
Water enters a very clayey subsoil from a sandy surface soil - ANSWERAs soon as the wetting front
reaches it
In a soil containing large holes or channels that are closed at the surface, water enters these large
holes - ANSWERonly after the surrounding soil is saturated
A soil with C/N ratio of 600:1 could be a material such as - ANSWERSawdust or leaves that have a low
N content and a high potential for N immobilization
Poorly defined organic substances that are complex, resistant to decay, and polymeric are -
ANSWERHumic substances
Which of the following could be used to improve soil organic matter in a cropping system? -
ANSWERReduce the plant materials that are harvested and return any residues back to the field
Water moves downward in a profile from the B horizon (clay loam) into gravel layer - ANSWEROnly
after the B horizon is saturated
As water is adsorbed by a dry soil, the soil matric potential of the dry soil - ANSWERIncreases
Water moves downward in a profile from the A horizon (sandy loam) to the B horizon (loam) -
ANSWERAs soon as the wetting front reaches the B horizon
Evaporation losses of water from soils may be reduced by - ANSWERCrop residue on the surface
Water is moving upward from an aquifer. The surface is clayey and the subsurface is a mix of coarse
sand and gravel. Which is true about movement of water from the coarse-textured subsurface to the
fine-textured surface? - ANSWERWater will not move from the coarse texture until it is saturated
