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Lecture Exam 2
Odom Soil Science
25
Agriculture
Undergraduate 2
05/02/2012

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Cards

Term
About 21% of the Earth's atmosphere is ____________
Definition
Oxygen
Term
When a soil is waterlogged, the oxygen content of the soil's air tends to _____________
Definition
go down
Term
Molecules of gas move by diffusion down a __________ gradient
Definition
concentration
Term
B Horizons tend to be ___________ aerated than A horizons.
Definition
less well
Term
Sandy soils have _________ large pored than clay soils.
Definition
more
Term
An acre furrow slice of soil weighs about ______________.
Definition
2 million pounds
Term
The boundary between two watersheds is a _____________.
Definition
divide
Term
Water will flow out of the ___________ into a hole.
Definition
zone of saturation
Term
To have a flowing artesian well, the recharge area for the aquifer must be __________ than the top of the well.
Definition
higher
Term
The Darcy's law conductivity of a soil __________ with drying.
Definition
decreases
Term
Water tends to flow __________.
Definition
down
Term
Water tends to flow _________
Definition
from larger to smaller pores.
Term
At the permanent wilting point of a soil, the relative humidity of the soil air is ___________
Definition
above 95%
Term
A lone silicon-oxygen tetrahedron carries a charge of _________
Definition
-4
Term
Apatite is a non-silicate mineral that supplies _____________ to plants as it weathers.
Definition
phosphorous
Term
Isomorphous substitution in clay minerals results in a net __________ charge
Definition
negative
Term
Kaolinite is a ______________ layer silicate
Definition
1:1
Term
Cation exchange in the soil _____________ the loss of cations from the soil by leaching.
Definition
slows
Term
The charge on the soil sesquioxides _____________ as the pH increases.
Definition
becomes more negative
Term
Aluminum ions are more _________ held than calcium ion by the soil colloids.
Definition
tightly
Term
Application of ground limestone ___________ the soil pH.
Definition
increases
Term
Sodic soils have high levels of ____________
Definition
sodium
Term
Humans are __________ mammals
Definition
placental
Term
Nitrification makes the soil _________acid.
Definition
more
Term
If the C/N ratio of a substrate being decayed is greater then 20, the decay microbes will __________.
Definition
take N from the soil
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