SWS3022 UF Exam 3 Questions with Correct Answers
The very high pH (>8.5) levels found in some arid regions are most likely due to the high levels of exchangeable_______: - Answer-Na
Sodic soils generally have a poor physical condition. To what is this most likely due? - Answer-Dispersion of ...
SWS3022 UF Exam 3 Questions
with Correct Answers
The very high pH (>8.5) levels found in some arid regions are most likely due to the high
levels of exchangeable_______: - Answer-Na
Sodic soils generally have a poor physical condition. To what is this most likely due? -
Answer-Dispersion of the Na-saturated soil colloids
Which of the following human activities is most apt to result in long term increase in soil
PH? - Answer-irrigation with high salt water
Which of the following is (are) greenhouse gas(es) contributed to the atmosphere by
soils? - Answer-nitrous oxide
carbon dioxide
methane
plants obtain nitrogen from soil solution by taking up - Answer-nitrate and ammonium
the exchange complexes of strongly acid mineral soils are characterized best by an
abundance of - Answer-exchangeable Al ions
the following soils had the same pH (5.0), which one will need the higher amounts of
lime to be added to bring the pH to 7.0? - Answer-a clay soil
The H+ ion concentration in solution is 0.001 M. What is the pH? - Answer-0.001 M.=
10-3m
PH=3
the pH of a soil is 6.0. what is the h+ ion concentration - Answer-10-6m or o.ooooo1 m
In many soils, the exchange sites often are dominated by 4 cations: calcium,
magnesium, potassium, and sodium. - Answer-t
To increase the pH of a soil, it would be necessary to add more limestone than would
be indicated by a measurement of the active acidity. - Answer-t
Aluminum is acidic in soils because it removes H+ from solution by hydrolysis. -
Answer-f
Soils often resist changes in pH due to exchangeable forms of acidity. - Answer-t
, You have two soils, A and B, which have the same cation exchange capacity. Soil A has
a pH of 4.0 and soil B has a pH of 8.0. Which soil likely will have the higher % base
saturation? - Answer-soil B
Hydrolysis is the splitting of water. - Answer-t
A common material used to raise the pH of soils is calcium chloride - Answer-t
It is easy to increase the pH of a soil with a high CEC and a low base saturation. -
Answer-f
The two ions considered acidic in soils are hydrogen and -----. - Answer-Al
A soil has a CEC of 100 cmol/kg. The exchange sites are occupied only by Na+, K+,
and H+. The concentration of Na+ on the exchange sites is 10 cmol/kg. The
concentration of K+ on the exchange sites is 30 cmol/kg. What is the % base saturation
of the soil? - Answer-40%
Note the various forms of N - Answer-1. Ammonium (NH4+) cation in the soil solution
and fixed in secondary clays
2. Nitrate (NO3-) anion in the soil solution
3. Organic N in the soil
4. Ammonia (NH3) gas (released to atmosphere)
5. NO, N2O, N2 gases (released to atmosphere)
anion- nitrogen - Answer-it is not held by soil colloids and can be lost from the soil
through leaching. However in well aerated soils (plenty of oxygen), most of the NH4+-N
(applied for example as fertilizer) changes to the NO3--N form by a process called
nitrification
cation-nitrogen - Answer-it can be held on the exchange sites of soil colloids which
makes it available for plant uptake over a long period of
time.
A soil has a thick black A horizon, base saturation greater than 50%, and a granular
structure. In which order is it most likely classed? - Answer-Mollisol
Describe one reaction that leads to loss of N from the soil: - Answer-Nitrate leaching
into ground
water.
symbiotic N2 fixation that occurs between legumes and rhizobium
species. - Answer-Host plant supplies the N fixing organisms with fixed C
(photosynthate which is used for respiration and N2 fixation), and the host plant benefits
from the fixed N.
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