Midterm review Flashcards
What is the pH of sodic soils?
> 8.5
Why are sodic soils high pH?
Sodium-clay, bicarbonate, and carbonate react with water to form hydroxyls.
What is the ESP of saline-sodic soils?
> 15%
What is the pH of saline-sodic soils?
<8.5
What is the EC of saline-sodic soils?
EC>4
How do you manage sodic soils?
Gypsum, sulfur, and irrigation.
What is the ESP of sodic soils?
> 15%
How do you manage saline soils?
Gypsum and irrigation.
What lime particle size is best to manage the pH of a highly buffered soil for 3 to 5 years?
Coarse particles will release slowly, resulting in a longer term change in pH, while finer textured particles could achieve immediate pH changes.
What is the EC of saline soils?
> 4
What is tortuosity?
A parameter defining the “twistedness” of a path; relating to soil nutrient diffusion, it specifies how indirect of a path a nutrient must take to diffuse.
Do sandy or clayey soils have higher tortuosity?
Sand, due to larger particle size and less contact between water films on particles.
What is the fastest moving nutrient in soil?
Nitrate
Between 1:1, 2:1, and OM, which requires the most fertilization to reach a certain nutrient concentration in the soil solution?
OM, because of the high buffering capacity.
How do you manage saline-sodic soils?
Gypsum and irrigation.
What is the pH of saline soils?
<8.5
What defines a saline-sodic soil?
EC>4
pH<8.5
ESP>15%
How does tortuosity affect diffusion rates?
Increasing tortuosity slows diffusion rates.
What is the difference between mass flow and diffusion?
Mass flow is driven by transpiration, diffusion by concentration gradients.
What is the slowest moving nutrient in soil?
Phosphorous
What is the EC of sodic soils?
<4
What is the ESP of saline soils?
<15%
(Monocots/Dicots) have higher CEC per root length.
Dicots
What defines a sodic soil?
EC<4
pH>8.5
ESP>15%
How does excess sodium affect pH?
Increases
What defines a saline soil?
EC>4
pH<8.5
ESP<15%
Liming reaction:
____+____<–>____+____+____
a)CaCO3
b)H2O
c)CO2
d)2H
e)Ca
a,d,e,c,b
