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Forage Crops - HCS412
Mid-term Exam
8:00-9:00 am 2 May 2002 or 10:00-11:00 am 3 May 2002
Instructions:
Complete Question #1 (required for everyone), and 9 others from the remaining
12.
All questions are worth the same: 10 points per question.
Show all computational work and units where applicable.
You have 48 minutes to complete the test.
Question
1 (required)
For your favorite
forage species, state:
a) Common name (0)
b) Latin/Scientific Name (1):
c) A variety of your species (1):
Write one key point on each of the following:
d) Most distinguishing
morphological feature to identify the species (2)
e) Main advantage or benefit of this species (3):
f) Biggest disadvantage or limitation of this species (3):
Question 2
For the species that you identified in Question 1, write 5 bullet-style points
describing additional aspects of the species not mentioned in Question 1.
One might think of sensitivity/tolerance to the environment, drought/freeze
tolerance, grazing suitability, insect/disease tolerance, feed quality, fertilizer
requirements, or other details.
Question 3
In either of the following diagrams of two forages, label a:
a) tiller b) stolon c) meristem d) lamina e) petiole f) rooted node
g) sheath (or pseudostem) h) ligule i) flower j) rhizome
Question 4
Complete the sentence with the most appropriate keyword from the list provided
a) The photoreduction process that converts radiant energy to chemical energy within the chloroplast of plants is … Photosynthesis
b) Most (>50%) of the protein in leaves is ……… Rubisco
c) Cool-season species have a temperature optimum for growth around 20oC,
but
…Warm-season ….. grasses have a temperature
optimum around 30-35oC
d) The cation-exchange capacity of soil results from the dissociation of
… Hydrogen ions …… from soil particles,
leaving areas of localized negative charge which can attract soil cations.
e) Excessive application of CaCO3 lime can result in displacement of … Magnesium ions … from the soil by calcium. This can be prevented by using dolomitic lime.
(Photosynthesis, Anions, Magnesium ions, Hydrogen ions, Rubisco, Warm-season,
Endophyte)
Question 5
a) List 2 sources of nitrogen input to the soil (2)
fertilizer, N-fixation, atmospheric deposition (pollution),
release from organic matter
b) List 2 losses of nitrogen from in the soil (2)
Plant and animal products, leaching, volatization
c) Define soil fertility (2)
The ability of the soil to provide the nutrients required
for plant growth
d) Write 2-3 sentences on why is soil fertility important (include mention
of the main components of soil fertility) (4)
Soil fertility is the basis for plant and animal production
The chemical composition provides nutrients
The physcial structure allows rooting, water movement and oxygen diffusion
Biological activity
Question 6
What effect does lime have on the soil? (5)
Increases pH, OH removes H+, increases CEC, adds Ca
which can displace Mg, improves soil structure
Why is liming important for forages? (5)
Many processes acidify the soil, liming establishes
the optimum pH, promotes earthworm activity
Increasing CEC increases nutrient availability
Good soil structure allows rooting, water infiltration and water holding capacity
Dolomitic lime adds essential Mg
Question 7
An alfalfa hayfield produces 5 ton/ac/year
a) If the harvested hay contains 2.5% K, how many pounds of K are removed
from an acre in one year? (2)
10,000 lbs hay/ac/yr x 0.025 lb K/lb hay = 250 lbK/ac/yr
b) On that same acre, how many pounds of 19-19-19 fertilizer would be required
to replace the K lost by crop removal? (4)
250 lb K/ac/yr / 0.83 lb K/lb
K20 / 0.19 lb K20/lb
fert = 1585 lb fert/ac/yr
c) Three fertilizers have the following characteristics. For each fertilizer
calculate the cost per unit K2O ($/lb K2O)
(3)
| Fertilizer form | %K2O | $/ton | $/lb K2O |
| 19-19-19 | 19% | $209.05 | a) 209.05/2000/0.19 = 0.55 $/lb K2O |
| 6-15-40 | 40% | $170.38 | b) 170.38/2000/0.40 = 0.21 $/lb K2O *** |
| 12-31-20 | 20% | $199.62 | c) 199.62/2000/0.20 = 0.50 $/lb K2O |
d) which fertilizer is the cheapest source of potash? (1)
6-15-40
Question 8 - multi-choice. Circle
the only correct answer
8.1 A stolon is:
a) An under-ground (burrowing) stem
b) An above-ground (creeping) stem
c) Part of all grass plants
d) Part of all legumes
8.2 The Latin name for perennial ryegrass is:
a) Lolium multiflorum
b) Lolium hybridium
c) Lolium perenne
d) none of the above
8.3 Compared to C3 species, warm season grasses are
a) more tolerant of dry conditions and low CO2
concentrations
b) less tolerant of dry conditions and low CO2 concentrations
c) more drought tolerant, but less tolerant of high temperatures (30oC)
d) less drought tolerant, but more tolerant of high temperatures (30oC)
8.4 The most important reserve for initial growth of forages in early-spring
is:
a) stored protein
b) stored carbohydrates
c) lignin
d) photosynthesis
8.5 The most water soluble (and volatile) nutrient is:
a) NO3-
b) SO4=
c) PO43-
d) Ca++
8.6 One important loss of PO43- from soil is:
a) Volatilization into the atmosphere
b) Leaching in drainage water
c) Adhering to soil particles that are lost into
waterways
d) All of the above
8.7 A fertilizer which has the specifications 6-15-40
has
a) 6% K
b) 40% K20
c) 40% K+
d) 15% K20
8.8 Endophyte fungi are found in the following forages
a) all grasses
b) orchardgrass, ryegrass and alfalfa
c) ryegrass and tall fescue
d) tall fescue and Kentucky bluegrass
8.9 Freezing tolerance and winter survival in alfalfa is improved by:
a) application of N fertilizer to promote fall growth
b) application of K fertilizer to enhance osmoprotection
c) close cutting before winter sets in
d) none of the above
8.10 Kentucky-31 is a common variety of:
a) white clover
b) crimson clover
c) kentucky bluegrass
d) tall fescue
Question 9
A productive legume can fix 200 lbN/ac/yr.
a) name 3 legume species that can fix this amount of N (3)
alfalfa, red clover, white clover
b) nitrogen is fixed by a symbiotic association with which bacteria? (1)
Rhizobia
c) how much urea would need to be applied to equal this rate of N fixation?
(2)
(urea = 46-0-0)
200/0.46 = 434.78 lb fert/ac/yr
d) What would this cost if it had to be applied as fertilizer? (2)
(urea = $186/ton)
434.78 x 186/2000 = $40.43/ac/yr
e) Urea application suppresses nitrogen fixation by 1 lb N-fixed/2 lb of
fert-N. If a farmer applied 100 lbN/acre/year, what would the resultant rate
of nitrogen fixation? (2)
Resultant rate = initial rate - suppression = 200 -
100/2 = 150 lbN fixed/ac/yr
Question 10
a) The red:far-red ratio determines many aspects of forage growth and development.
What is one effect of red light on forages? (2)
Photosynthesis, tiller initiation, short inter-nodes
in clover
b) What is one effect of far-red light on forages? (2)
Etiolation, tiller suppression, increased internodes
c) Why are forages (and all plants) green? (2)
Green light is reflected or transmitted
d) What is vernalization? (2)
Cold (freezing) period required that is required before
flowering can occur
e) What is meant when plants are categorized as "long-day plants"?
(2)
They require long days (short nights) to flower
Question 11
a) What is endophyte? (2)
Intercellular fungus
b) Name one forage species that can be infected with endophyte (1)
Ryegrass or fescue (or others)
c) Name one forage species that does not have endophyte (1)
All legumes, orchardgrass, Kentucky bluegrass
d) What are two animal symptoms of endophyte toxicity? (2)
Slowed growth, elevated temperature, fescue foot, staggers
e) Currently there is an emphasis to have endophyte-free forage. What are
two sources of contamination in "clean" forage. (2)
Contaminated seed, buried seed, hay, seed in manure,
plants surviving cultivation
f) What are novel endophytes? (2)
Endophytes with different alkaloid profiles (e.g. no
ergovaline)
Question 12
Sustainability means different things to different people, and is virtually
impossible to define. However, there are some important themes that are implied
in sustainability. Name 4 of these. (4)
a) ecosystem services e.g. food production and resource
protection
b) economics
c) social goals (e.g. lifestyle, community)
d) plant and animal diversity
Give 6 ways that forage-based farming systems might be more sustainable than traditional cropping systems (6)
a) less fertilizer
b) less compaction
c) N-fixation
d) lower costs
e) less fossil fuel
f) less labor
Question 13
Nitrogen, sulphur and phosphorous are all anions with contrasting chemistry
that influences their importance in agriculture.
a) Which is the most important in determining the short-term (1-2 month) growth
of forages? (2)
N
b) Which is the most important in determining the long-term (1-2 year) growth
of forages? (2)
P
c) Which is the least limiting to forage growth in USA? (2)
S
d) Which is the most soluble and volatile? (2)
N
e) Which has the greatest potential to accumulate in soil? (2)
P
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