Soils Exam 2 Flashcards
When does run off occur
When accumulation exceeds rare if infiltration or soil storage capacity
Interception
Precipitation that never reaches soil due to vegetation
Material that reduces evaporation and controls weeds
Mulch
Eutrophication
Excess nutrients (phosphorus) that leads to excessive aquatic growth and ultimately oxygen depletion
Oxidation if pyrite produces extreme acidity and soluble iron and sulfur
Acid mine drainage
The ability if soils to bind chemical substances depends on these 3 things:
Chemical characteristics if substance
Characteristics if soil
Provides maximum opportunity for soils to bind chemicals:
Matrix flow
Greatly decreases the ability if a soil to bond chemicals
Macropore flow
Preferential or bypass flow
Transports chemicals to groundwater more rapidly via macro pores
Oxygen concentration does what as soil depth increases?
Decreases
High saturation levels does what to o2 content?
Lowers it
What are concentrations of co2 like beneath the soil surface.
It can be 10 to 100 times greater and be toxic
What can anaerobic conditions in soil lead to?
Production of reduced nitrogen gases, methane gases, hydrogen sulfide, ethylene
What 2 things regulate o2 availability?
Soil macro porosity and water content
What two ways does soul gas exchange?
Mass flow and diffusion
What is the more important form of soil gas exchange?
Diffusion
What is mass flow?
Physical movement if air due to fluctuations in moisture content
Why does diffusion occur?
Concentration gradients
What is the partial pressure gradient?
A difference in every potential of gas concentration
At what percentage air porosity dies microbial and root respiration cease?
10
What does water do to diffusion?
Slows it because it moves 10000 times slower
Loss of electrons in a substance
Oxidation
The gain of electrons
Reduction
What is the electron receptor for respiration?
Oxygen
