Section 3 - Test 3 Flashcards by Brandon Holland

Which of the following is NOT one of the diagnostic techniques used to determine potential nutrient stress?

Soil analysis
Remote sensing
Yield potential
Visual deficiency symptoms of plants

Yield potential

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Which of the following is a postmortem analysis?

stem test
diagnosing plant deficiency symptoms
grain analysis
cell sap test

grain analysis

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Which of the following is NOT a characteristic of a visual nutrient-deficiency symptom of a plant?

chlorosis
lush
stunting
necrosis

lush

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It is not difficult to tell if a given plant is suffering from immobile plant nutrient because:

immobile nutrient deficiency symptoms show up at older and lower leaves.

immobile nutrient deficiency symptoms show up at younger and upper leaves.

immobile nutrient deficiency symptoms show up in lower and upper leaves.

immobile nutrients are also immobile in soil

immobile nutrient deficiency symptoms show up at younger and upper leaves.

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The numerical values of plant critical nutrient range (CNR) and critical nutrient concentration (CNC) are the same for N uptake of different plants under well-managed conditions.

True
False

False

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Most of the error in soil testing processes is due to:

soil sampling
errors of analytical instrumentation
computer error during data acquisition and output generation
interpretation of soil test results

soil sampling

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Soil extractants used in different soil test labs measure:

the concentration nutrient in soil
the total nutrient content in the soil
the potential plant available soil nutrient in the soil
the maximum amount of nutrient a soil can supply

the potential plant available soil nutrient in the soil

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Since soil testing is a science, if you send your sample to different labs to make a recommendation for a given soil nutrient and plant, you will get the same recommendation if you are in the same regions of the continental US.

True
False

False

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Maximum yield will always result in maximum profit no matter what crop you are producing.

True
False

False

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Plants selectively take the correct amount of the essential nutrients they need and they do not unnecessarily waste any.

True
False

False

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As the saying “Out of sight, out of mind” goes, plant nutrient deficiency impact is studied only for above-ground plant parts since roots rarely experience nutrient deficiency.

True
False

False

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The downside of using the nutrient balance in the soil as a tool for their availability is that the ratio may not indicate their potential availability to plants.

True
False

True

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Which of the following is a disadvantage of broadcast application?

Broadcast nutrients cannot be tilled into soil.
Broadcast application is expensive as it needs to be reapplied during fall and winter.
Broadcast, incorporated nutrients increase potential soil nutrient erosion.
Application of large amounts of fertilizer sometimes results in plant injury.

Broadcast, incorporated nutrients increase potential soil nutrient erosion.

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Which of the following is an advantage of foliar application?

The nutrient response can be high if the plant is severely deficient.
Solution concentration is generally small and reduces the need for repeated application.
Weather conditions do not influence the nutrient absorption rate
The nutrient applied will be highly compatible with pesticides.

The nutrient response can be high if the plant is severely deficient.

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A nutrient management plan is being developed for an agricultural field. In order to attain increased plant productivity (yield and quality) and profitability, which of the following should not be implemented?

Estimating nutrient needs through realistic yield expectations.
Recognizing specific plants with high requirements for certain nutrients.
Apply mobile nutrients just after the maximum uptake or growth period.
Review plant analysis information for areas with nutrient levels below or above their critical range.

Apply mobile nutrients just after the maximum uptake or growth period.

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It is highly recommended to apply plant nutrients at planting, a month after planting, and when seed formation is complete.

True
False

False

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Plant nutrient management is not affected by:

cloud cover
soil environment
BMPs
plant characterstics

cloud cover

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Fertilizer placement options generally involve surface applications before, after, and at planting.

True
False

True

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____________________ is an essential primary macronutrient that is taken up the most by plants under normal conditions.

N
Ca
P
Al

If most of your plant roots are restricted to the top 0-5 cm soil depth, the possible reasons could be:

too much P fixation in top 0-5 cm depth.
soil organic matter accumulation below 5 cm.
intensive microbial activity below 5 cm
soil compaction

soil compaction

In general, at least 50% of the foliar-applied nutrients are absorbed by plant leaves within seconds, minutes, and hours, and none will last more than a day.

True
False

False

The best way to optimize yield and profit is by applying variable rates of plant nutrients to a specific location according to its needs through precision farming.

True
False

True

Plant root length and root density do not impact nutrient uptake quantity since most plant nutrients reside in the top few centimeters of the topsoil.

True
False

False

For high potential yield, high amounts of N-P-K need to be applied but even doing this will not overcome the eventual natural limitations to increase yield indefinitely.

True
False

True

Advantages of efficient nutrient management does not include: resource conservation, especially P eutrophication potential maximum profit potential maximum yield

eutrophication

Caution must be exercised in the interpretation of plant nutrient concentrations and ratios since 400 ppm Ca and 40 ppm Mg will have the same ratio as 0.4 ppm Ca and 0.04 Mg in soil solution or on soil colloid. True False

True

Which of the following is not important to consider when purchasing a fertilizer item? color potential explosion during storage and/or application potential acidity potential salt index

color

The four Rs of fertilizer nutrient stewardships do not include: right time right soil test right amount right source

right soil test

In a corn-soybean rotation and corn monocropping systems, if you apply the same amount of fertilizers to both practices, you will attain the same maximum and profitable yields during a normal crop year. True False

False

______________________ represents the yield level where the last unit of input pays for itself and is less than the maximum yield. Minimum economic yield Maximum economic yield The first derivation of the quadratic equation relating yield to nutrient applied. Minimum quadratic yield

Maximum economic yield

Which of the following is a crop factor that influences nutrient responses? soil tillage row spacing Plant available water compaction

row spacing

Which of the following soil nutrients is most immobile in soil and is most advantegeous when placed near the roots? P N Zn K

____________________ represents crop yield per unit of water used from soil, precipitation, and irrigation. WUE NUE/WUE NUE NPK

WUE

Which of the following defines the low of diminishing returns? Adding one nutrient, while holding all others constant, will after a point show no per-unit response to the nutrient. Adding more than one nutrient, while holding all others constant, will at some point reduce the per-unit response of another nutrient. Adding more of the nutrient, while holding all others constant, will at some point yield a lower per-unit response to the nutrients than realized earlier. Adding more of one nutrient, while holding all others constant, will at some point rapidly decline the per-unit response to the nutrient than realized earlier.

Adding more of the nutrient, while holding all others constant, will at some point yield a lower per-unit response to the nutrients than realized earlier.

A corn farm is fertilized with NPK fertilizers and the residual values of P and N after two years are found to be 26% and 45%, respectively. Which of the following is an appropriate conclusion? Soil has high P-fixing capacity Soil has low P-fixing capacity The rate of application of P has been increased for 2 years. The crop uptake of N has exceeded P.

Soil has high P-fixing capacity

If a plant yield is 130 bu/a at zero Zn rate and high P rate, but 120 bu/a high Zn and zero P rate, this is a good illustration of a negative interaction between Zn and P. True False

True

The yield response to N in NPK fertilizers applied to a rice farm is represented as Y= 75.4 + 0.45X -0.0040X2 where Y yield in bu/a and X is N lb/a. What would be the amount of the N rate for maximum yield? 56. 2 55. 3 46. 2 75. 2

56.2

Which of the following is the cheapest buy based on its unit price ($/lb P2O5)? A = $650/ton of 0-30-0 B= $300/ton of 0-12-0 C= $ 400/ton of 0-47-0 D= $ 700/ton 0-35-0

C= $ 400/ton of 0-47-0

There are three types of nutrient interactions, negative, neutral, and quadratic. True False

False

The Green Revolution that significantly increased food production in developing countries did not utilize : revolutionary political theory fertilizers BMPs hybrid varieties

revolutionary political theory

In a greenhouse experiment, you collected 2000 lb of soil and you wanted to apply NH4NO3 (34% N), TSP (46% P2O5), and muriate of potash (60% K2O) at 100-100-100 lb/a rate. How many lb of each fertilizer do you have to weigh and mix with your 2000 lb soil? (Assume an acre weighs 2 million lb.)

Amount needed to make 100 lb/a for each nutrient: NH4NO3 = 100/0.34=294.1 lb/a TSP= 100/0.46=217.3 lb/a Muriate of potash= 100/0.60=166.6 lb/a Since an acre 2,000,000 lb, amount needed for 2,000 would be: NH4NO3 = 294.1/2000000*2000 = 0.294 lb TSP = 217.3/2000000*2000 = 0.217 lb Muriate of potash =166.6/2000000*2000 = 0.166 lb

How many lb of N-P-K do you need to weigh and mix from 10-46-0, 0-0-28, and 0-0-60 to make 10,000 lb of 5-5-5 grade?

Start with 10-46-0 first since it has both N and P Need 5% of each nutrient so 10000 * 0.05 = 500 lbs of each N, P, and K P2O5 = 500 lbs / 0.46 = 1086.96 lbs 10-46-0 for 500 lbs of P N in 1086.96 * 0.10 = 108.7 lbs N from the 10-46-0. So need 500-108.7 = 391.3 more lbs N 391.3 / 0.28 =1397.5 lbs 28-0-0 for 391.3 lbs N K2O = 500/.60 = 833.33 lbs 0-0-60 for 500 of K2O Total = 1086.96 + 1397.5 + 833.33 = 3317.79 lbs fertilizer. Filler needed would 10000-3317.79 = 6682.21 lbs.

Broadcast applied N usually is less efficient than subsurface applied N in high surface residue cropping systems. Using the following data to calculate the % fertilizer N recovery for each system. What caused the difference? Broadcast N Subsurface N Unfertilized N rate 100 lb N/a 100 lb N/a 0 lb N/a Grain yield 100 bu/a 120 bu/a 50 bu/a Test Weight 56 lb/bu 56 lb/bu 56 lb/bu % Grain N 2.1% 2.4% 1.8%

Unfertilized N uptake = 50*56*0.018/100 = 50.4 lb/a Subsurface N uptake = 120*56*2.4/100 = 161.28 lb/a Broadcast N uptake = 100*56*2.1/100 = 117.6 lb/a % N Recovery = (N application of N uptake - N in unfertilized)*100/N applied % N recovery for subsurface = (161.28 - 50.4/100)*100 = 110.88% % N recovery for broadcast = (117.6 - 50.4/100)*100. =. 67.2 % The subsurface banding if way more efficient than broadcastings due to less loss to volatilization and runoff. Having the nutrients at the root zone helps the plant take up more nitrogen more efficiently.

The AU Soil Testing lab analyzed a soil sample from your 1500 ft2 area lawn and gave you two recommendations as 120 lb N/a and 2.75 lb N/1000 ft2. (a) Are these two recommendations the same? (b) how many lb N do you need to apply to your lawn using urea (46-0-0) for 120 lb N/a and 2.57 lb N/1000 ft2? (Assume the area of an acre is 43,560 ft2 and an acre weighs 2 million lbs.)

(a) 1000 ft2/ 43560 ft2= 0.023 acres Recommendation = 120 lbs N/acre x 0.023 = 2.75 lbs Thus, they are the same!!! (b) Lawn recom. = (2.75/0.46) x 1500 ft2/1000 ft2) = 8.97 lbs 46-0-0 using 120 lbs N/a = (120 lbs x 1/0.46) x 1500 ft2/43560 ft2) = 8.98 lb of 46-0-0

A soil testing lab is transitioning from the traditional lb/a to ppm and, also from reporting N-P2O5-K2O to N(%), P(%), and K(%). Your traditional recommendation was 100-80-120 lb/a. What would be this new recommendation in ppm and in elemental forms of N, P, and K percentages?

``` (lb/a)/2 = ppm N 100/2 = 50 ppm P2O5 80/2 = 40 ppm K2O 120/2 = 60 ppm Recommendation (ppm) = 50-40-60 ppm/10,000 = % % N = 50/10,000 = 0.005 % P = 40 * 0.44/10,000 = 0.00176 %K = 60 ppm* 0.83/10,000 = 0.00498 ```