SWS3022 UF EXAM 3 QUESTIONS
AND ANSWERS 100% PASS
Note the various forms of N - ✔✔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 - ✔✔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 - ✔✔it can be held on the exchange sites of soil colloids which makes it
available for plant uptake over a long period of
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,time.
Describe one reaction that leads to loss of N from the soil: - ✔✔Nitrate leaching into
ground
water.
symbiotic N2 fixation that occurs between legumes and rhizobium
species. - ✔✔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.
N2 fixation is a reduction reaction and happens in the nodule in a completely anaerobic
environment
inorganic P - ✔✔found in insoluble compounds in the soil
N is found in two forms: - ✔✔1) Ammonium (NH4+) - cation
2) Nitrate (NO3-) - anion
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, NH4 and NO3 in soil solution constitute about 1% of N in the soil. Again most of the N
in soils is in organic forms.
Due to rapid nitrification in soils, plants absorb predominately NO3.
Some plants prefer N in the NH4 form for example rice. Other plans that grow under
acidic conditions seem to prefer NH4 too.
ATP - ✔✔adenosine triphosphate (drives most energy-requiring biochemical processes
ex uptake of nutrient)
DNA - ✔✔DNA - Deoxyribonucleic acid (genetic inheritance)
RNA - ✔✔RNA - Ribonucleic acid (protein synthesis in plants and animals)
Finally P content in plants: - ✔✔0.1 - 0.4% in plant tissue depending on plant.
Plants' P uptake ranges between 6-26 kg/ha or 5-23 lbs/acre of P.
Please note that 1% = 10 000 ppm (mg/ kg) so 0.1% is = 1000 mg P/ kg of plant tissue
P deficiency - ✔✔1.Stunted growth; thin stemmed dark foliage (bluish green)
Katelyn Whitman, All Rights Reserved © 2025 3
AND ANSWERS 100% PASS
Note the various forms of N - ✔✔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 - ✔✔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 - ✔✔it can be held on the exchange sites of soil colloids which makes it
available for plant uptake over a long period of
Katelyn Whitman, All Rights Reserved © 2025 1
,time.
Describe one reaction that leads to loss of N from the soil: - ✔✔Nitrate leaching into
ground
water.
symbiotic N2 fixation that occurs between legumes and rhizobium
species. - ✔✔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.
N2 fixation is a reduction reaction and happens in the nodule in a completely anaerobic
environment
inorganic P - ✔✔found in insoluble compounds in the soil
N is found in two forms: - ✔✔1) Ammonium (NH4+) - cation
2) Nitrate (NO3-) - anion
Katelyn Whitman, All Rights Reserved © 2025 2
, NH4 and NO3 in soil solution constitute about 1% of N in the soil. Again most of the N
in soils is in organic forms.
Due to rapid nitrification in soils, plants absorb predominately NO3.
Some plants prefer N in the NH4 form for example rice. Other plans that grow under
acidic conditions seem to prefer NH4 too.
ATP - ✔✔adenosine triphosphate (drives most energy-requiring biochemical processes
ex uptake of nutrient)
DNA - ✔✔DNA - Deoxyribonucleic acid (genetic inheritance)
RNA - ✔✔RNA - Ribonucleic acid (protein synthesis in plants and animals)
Finally P content in plants: - ✔✔0.1 - 0.4% in plant tissue depending on plant.
Plants' P uptake ranges between 6-26 kg/ha or 5-23 lbs/acre of P.
Please note that 1% = 10 000 ppm (mg/ kg) so 0.1% is = 1000 mg P/ kg of plant tissue
P deficiency - ✔✔1.Stunted growth; thin stemmed dark foliage (bluish green)
Katelyn Whitman, All Rights Reserved © 2025 3
