Name: ___________________________
AGRONOMY 354
Test 4
November 18, 2015
INDICATE THE ONE BEST RESPONSE. Please cover your answers when not writing.
1.
The lower leaves of a corn plant have turned a yellowish brown color beginning at the tips and
progressing along the midribs. The expected deficiency is:
a) Ca. b) K. c) N. d) P. e) Zn.
2.
The cation exchange capacity of plant roots give legumes a competitive advantage over grasses
for:
a) absorbing Ca2+.
b) absorbing H2O.
c) absorbing K+.
d) eliminating CO2.
e) absorbing Fe3+.
3.
This micronutrient is deficient in more soils of the world than any other micronutrient.
a) zinc b) copper c) iron d) boron e) molybdenum
4.
The highest percentage N fertilizer in the solid form one can buy commercially is:
a) ammonium nitrate.
b) urea.
c) potassium nitrate.
d) ammonium chloride.
e) anhydrous ammonia.
5.
Iron and manganese deficiency symptoms show more in _______ than chlorosis resulting from
nitrogen, potassium, or magnesium deficiency.
a) older leaves
b) young leaves
c) stems
d) vascular tissue
e) stomates
6.
Sulfur in surface soils occurs mainly as:
a) SO42-.
b) H2S.
c) organic S.
d) gaseous S.
e) S2O3.
7.
Industrial production of N fertilizers today:
a) comes mainly from the cyanamide process.
b) is based on an electrical discharge forming nitrogen oxide.
c) is mainly in the form of ammonium nitrate.
d) comes mainly from synthetic ammonia.
e) comes mainly from biological nitrogen fixation.
8.
Identify the correct statement concerning K in Iowa soils.
a) exchangeable K often exceeds K found in primary minerals
b) soluble K in an acre root zone often exceeds 50 lbs
c) surface soil is expected to contain about 1.5% K
d) up to 40% of the K is expected to be in secondary minerals
e) the K found in primary minerals is equal in availability to that in secondary minerals
9.
According to your reading, urea formaldehyde is used:
a) to control denitrification.
b) to provide both N and K.
c) as a slow release N source.
d) to reduce ammonium fixation.
e) to provide both ammonium and nitrate.
10.
You have forgotten the percentage of N in (NH4)2SO4 but are not worried because you can
calculate it from atomic weights (N=14, S= 32, O=16, H=1). It is ____% N.
a) 11 b) 14 c) 21 d) 28 e) 32
11.
This essential nutrient may be deficient for plant growth even when the soil contains several
thousand pounds of it per acre furrow-slice.
a) boron b) calcium c) iron d) zinc e) aluminum
12.
One nitrogen fertilizer is called “milorganite” and it:
a) contains approximately 25% nitrogen.
b) is a slow release fertilizer.
c) was the first inorganic nitrogen carrier.
d) should be used with a urease inhibitor to get full benefit of the nitrogen.
e) is commonly used in Third-world countries.
13.
Fifty pounds per acre of available boron present in the soil would probably:
a) be toxic to animals but not to plants.
b) be toxic to plants.
c) indicate a need to apply borax as a fertilizer.
d) produce a good crop.
14.
Under which of these soil conditions would you most likely expect sulfur deficiencies in plants.
a) sandy, high rainfall
b) clayey, high rainfall
c) sandy, low rainfall
d) clayey, low rainfall
e) unrelated to soil texture and rainfall
15.
Chelates are likely to be the best form of fertilizer to apply to soil to overcome plant nutrient
deficiencies of:
a) aluminum. b) boron. c) calcium. d) potassium. e) zinc.
16.
Potassium tests for fertilizer recommendations are usually designed to measure exchangeable K
because exchangeable K is:
a) a sizable reserve of available K that can be replenished from other sources.
b) the most abundant form of K in the soil.
c) the most readily available form of K in the soil.
d) the only form of K that is convenient to measure.
17.
As discussed in lecture, the EPA limits of nitrate in drinking water, when expressed as NO3 and not
NO3-N, is:
a) 5 ppm NO3.
b) 10 ppm NO3.
c) 45 ppm NO3.
d) 75 ppm NO3.
e) 100 ppm NO3.
18.
Which fertilizer must necessarily be injected into a soil rather than applied at the surface?
a) anhydrous ammonia
b) ammonium nitrate
c) potassium chloride
d) potassium nitrate
e) urea
2
19.
Identify the true statement concerning micronutrients.
a) all crops require very similar quantities
b) the availability of all but one micronutrient increases at higher pH
c) there is usually little problem if more than required amounts are applied
d) verify the need for micronutrients before applying
20.
Per unit of N, which of these fertilizers would cause the most reduction of soil pH?
a) urea b) NH3 c) (NH4)2SO4 d) NH4NO3 e) all are expected to be equal
21.
According to your reading, the inhibitory action of poor aeration on nutrient uptake is most
pronounced with _______.
a) K b) N c) P d) both P and K e) equally across all three macronutrients
22.
In an experiment on a heavy-textured soil, North Dakota wheat gave a greater positive response
with spring-applied K than with fall-applied K. What is the best explanation?
a) the spring-applied K was not converted to unavailable forms
b) the K leached from the soil during the winter months
c) microbes oxidized the K into an unavailable form with the fall application
d) less volatile losses occurred with the spring application
23.
Surface application of _____ on a moist, alkaline soil is likely to result in a large loss of N by NH3
volatilization.
a) ammonium nitrate
b) ammonium phosphate
c) ammonium sulfate
d) potassium nitrate
e) urea
24.
An application of 5 tons/acre of wet cattle manure before planting corn is expected to:
a) have negligible effect (<5%) on the need for N fertilizer.
b) reduce the N fertilizer need by a significant fraction.
c) supply most if not all of the N needed.
d) supply excessive amounts of N.
25.
Most of the potassium absorbed by growing plants in Iowa reaches the plant roots by:
a) diffusion from zones within 1/2" to 1" from the roots.
b) diffusion from zones within 1/4" to the roots.
c) mass movement in water flowing to the roots.
d) roots interception as the roots grow.
3
POSSIBLE POINTS ARE INDICATED IN THE LEFT-HAND COLUMN.
26. Briefly describe how potassium fertilizers are produced, from the raw materials to the finished
product.
(5)
27.
Indicate to a University of Iowa graduate the main functions of micronutrients and why they are
needed for plant growth only in small amounts.
(5)
28.
(5)
Why do we predict that sulfur deficiencies will increase in future years?
29.
(5)
What is the ‘blue baby syndrome’ and why is it a concern?
Part 1 _______
Part 2 _______
Total _______
4