Name ___________________________
Circle
the one best answer (2 point each)
1. Which form of S in soils is thought to be
the most important source for S that will be mineralized during the growing
season?
a. ester
sulfate
b. carbon-bounded
S
c. calcium
carbonate-sulfates
d. FeS
2. Why is elemental S not directly available
to plants in an aerobic soil?
a. Forms
insoluble S compounds
b. Is
reduced to S2-
c. Forms
H2S which needs
to be oxidized first.
d. Must
first be oxidized to form SO42-
3. Which micronutrient increases in
availability with increasing pH?
a. Cu b.
Mo c. Zn d. Mn e.
None of these
4. Soil solution K:
a. is
unavailable for plants
b. is
slowly available to plants
c. is
available to plants
d. is
the same as exchangeable K
5. Which of the following would be the
condition and explanation for a toxicity of Mn on plants?
a. alkaline (> pH 7.5)/aerobic soil and
precipitation of Mn to insoluble precipitates
b. Acid (< pH 5.2)/anaerobic soil where Mn 4+
is converted to Mn 2+
c. Alkaline (> pH 7.5)/anaerobic soil and
reduction of Fe3+ to Fe2+
d.
Acid (< pH 5.2)/aerobic soil where
Al interferes with Mn uptake by plants
Underline
the term(s) that correctly completes the sentence (-1 point for each incorrect
answer up to zero)
(4) 6. Ammonium
polyphosphate: is normally a (solid, liquid, prill) fertilizer; can be used for
(multi nutrient, pesticide) mixes; and must (react with organic matter, be
hydrolyzed, sorbed) before it can be taken up by plants.
8. Match terms with the most appropriate response (you can use a response more than once) (1 point each)
_____ Rock phosphate a. Requires pressurized equipment _____ monoammonium phosphate b. Composting with manure can increase its availability _____ ordinary orthophosphate c. Starter or pop up fertilizer _____ chelate d. Formerly an important source of S _____ potassium e. Used with B to make it more avialable f. Manufactured by density separation of nutrient from impurities in mined material g. Used with Fe to keep it soluble h. When used with a micronutrient higher rates are needed
(8) 9.
The soil test for K is pretty good for predicting K deficiencies or
adequacy for crop production but S is not very good in many soils/environments. (a) What is measured for K and S in soil
tests? (b) Contrast the pools and cycling of K and S and explain why these 2
soil tests do not have the same effectiveness to make fertilizer
recommendations.
(3) 10. Give
a general reaction for Fe3+ in alkaline soils and indicate how this
affects Fe availability to plants
(5) 11. Write
your own question and answer on either Mg or Ca (2 pts. for questions and 3 for
answer). Put some thought into this –
if you ask a simple question and give a simple answer, even if correct, you
will not get full credit.