Name ____________________________
AGRONOMY 375
EXAM II
November 4, 2011
There are 14 questions (plus a bonus question) worth a
total of up to 100 points possible. Please be concise.
4 pts.
1. What is indicated by a mottled appearance in the top 13 to 18 inches of a soil profile.
Please explain.
8 pts.
2. List four problems associated with poor soil drainage in a corn and soybean production
environment in Indiana.
a)
b)
c)
d)
3 pts.
3.
3 pts.
4 pts.
a) What is the typical depth of placement for pattern field tile lateral systems installed
for subsurface drainage in Indiana corn and soybean production systems?
b) Please describe one method by which surface drainage can be managed in corn and
soybean production systems.
4.
Herbicides are commonly used for the chemical control of weeds in crop systems.
However, crop systems also generally include cultural and mechanical controls for
weeds as well. Briefly give an example of a cultural weed control component of a corn
or soybean production system used either today or in the past.
2
9 pts
5. Please note three crop management strategies which may be used to lessen and/or slow the
development of herbicide resistant weeds within a corn / soybean production
environment.
a)
b)
c)
6 pts.
6. Note three ways by which pollination by specified parent lines is controlled in a hybrid
seed corn production field.
a)
b)
c)
6 pts. 7. Please describe two aspects of how upright leaf orientation contributes to improved yield
potential in today’s corn hybrids.
a)
b)
6 pts. 8.
Why is seed corn typically harvested at high moisture (e. g. at 30 %) and on the ear (vs.
shelled)? Please note two reasons.
a)
b)
2 pts. 9.
a) A corn hybrid is listed as 3000 GDD comparative relative maturity (CRM) from
planting to physiological maturity. How would this hybrid be listed in terms of days
comparative relative maturity? (please show your work for partial credit)
________ GDD comparative relative maturity
2 pts.
b) Please define “Full Season” as it pertains to the season length requirement of a corn
hybrid. Note: Your definition should work equally well independent of location.
3
The following information pertains to questions 10, 11, and 12. Please show your work.
Corn Yield Goal:
225 bu/acre
Previous Crop:
65 bu/acre soybeans
P1 Soil Test:
37 ppm available P/acre
K Soil Test:
128 ppm exchangeable K/acre
C.E.C. =
16 meq / 100 grams of soil
11-52-0 will be used to apply the P2O5 and a portion of the Nitrogen needed while
the remainder of the N fertilizer is to be applied as side dressed anhydrous ammonia
(NH3 at 82% N content) within the first 30 days after planting.
Please make the appropriate fertilizer recommendations for next year's corn crop
(include your calculations for credit). Hint: First calculate your 11-52-0 requirement for
question 11 and then solve question 10, keeping in mind that a portion of your applied
fertilizer N requirement is met by the application of 11-52-0.
7 pts.
10.
2 pts.
7 pts.
b) Pounds of anhydrous ammonia (NH3 at 82% N content) to be side-dressed per acre:
11.
2 pts.
7 pts.
2 pts.
a) Total pounds of commercial fertilizer N to be applied per acre as 11-52-0 plus
NH3. Use the yield-based equation to calculate total N to be applied.
Annual pounds P2O5 per acre:
Total annual pounds 11-52-0 per acre:
12.
Annual K2O (pounds per acre):
Total annual pounds 0-0-60 per acre.
4
12 pts.. 13.
Yield-based recommendations have been the historical norm in managing N fertilization
for corn in the eastern Corn Belt of the U.S. However, in some conditions, traditional
yield based N recommendations may err high or low relative to the actual economic
optimum N fertilizer recommendation. Briefly discuss four factors which may vary and
thereby result in the economic optimum N fertilizer being lower or higher in some
situations than otherwise recommended by a traditional yield-based N approach.
a)
b)
c)
d)
8 pts.
14.
Briefly describe four factors which contribute to increased yield and / or profit potential
for corn planted early (e.g. April 29 vs. May 15) in central Indiana.
a)
b)
c)
d)
5 pts. BONUS You have harvested an on-farm corn test strip which is 2250 feet long and 8 rows wide.
Row width is 30 inches so the overall width of the test area is 20 feet. Total grain
weight is measured at 11,500 pounds at 18% moisture. What is the grain yield for this
test strip (please show your work and report your answer as bushels per acre adjusted to
15.5% moisture)?