Exam 2 Flashcards
0 bars
Saturation
-1/3 bars
Feild Capacity
-15 bars
Permanent Wilting Point
-31 bars
Hygroscopic Coefficient
-10,000 bars
Oven Dry
Leaching of anions out of the soil
Lower
Acid Precipitation
Lower
Nutrient Uptake
Lower
Decomposition of plant residues
Raise
Nitrogen fertilization
Lower
Adding Lime
Raise
Recycling of basic cations by deep rooted plants
Raise
Water classification where evaporation stops and the soil is said to be air-dry.
Hygroscopic Coefficient
Which of the water potential values indicates water that is held most tightly to soil?
-3100 kPa
Which increases evapotranspiration?
Increasing wind
Which of the following is NOT a device that measures soil moisture?
pressure plate apparatus
Which force moves free water in the soil out of the macropores?
gravitational
Irrigation can lead to the build up of too much
Nitrogen
Which of the following textural classes holds the least amount of PAW?
Sand
The water classification where drainage stops because the matric potential balances the gravitational pull and the macropores are empty is called:
Field Capacity
The movement of free water is dependent on the amount and continuity of
Macropores
This type of water is energetically available to plants (plants have enough energy to use it) but is NOT useable by plants because no oxygen is present.
Free/Gravitational water
How should a sandy soil be watered vs. a clay soil?
Sandy Soil more often with less water each time
Plant available water depends on or is a function of the soil’s _______________ and ____________ _____________ content.
Texture, Organic Matter
Bonding of water to another water molecule is called:
cohesion
Evapotranspiration is the loss of water by evaporation from the soil and transpiration through plant leaves.
True
Which of the following irrigation methods is the LEAST efficient in conserving water?
Flood
A portion of this water is energetically not availabe to plants.
Capillary Water
Bonding of water to the soil surface is called:
Adhesion
Is water held from -15 to -10,000 bar plant available?
No, Not Energetically Available
The entry of water downward through the soil surface is called:
infiltration
The attraction between water and soil surfaces is described by which component of water potential?
Matric
Is water held from 0 to -1/3 bar plant available?
No, No Oxygen
All of this water is energetically not available to plants (plants do not have enough energy to use it).
Hygroscopic Water
How should a sandy soil be watered vs. a clay soil?
Sandy Soil more often with less water each time
Cation exchange is an example of an
Adsorption process
The surface charge of most clays is negative.
True
The cation exchange sites (surfaces) of soil clays adsorb negatively charged particles.
False
CEC is the abbreviation for:
Cation Exchange Capacity
Which soil horizon would have the lowest CEC?
C
Attraction of ions to surface solids is the definition of
adsorption
check the four properties that cation exchange controls in soil
buffering of soil pH, leaching of cations, nutrient adsorption by plants, soil weathering
Which soil particle has the highest CEC?
Humus
The humus content in the soil is dependent on:
all of these answers influence humus content in soil
Colloidal properties are exhibited by which soil size separate:
Clay
Anion exchange occurs in some tropical areas and is when the soil is positively (+) charged and attracts negatively (-) charged ions called anions.
True
Normal range on pH scale:
0-14
Neutral soils
7 PH
Acid/Acidic PH
0 to 7
Basic PH
7 to 14
Which of the following is a cation?
K+
Cation Exchange Capacity is measured in
meq/ 100g
