CCA Certified Crop Adviser Exam — Questions and Answers

Question 1: A CCA is evaluating a field's potassium status where soil test K is 80 ppm (160 lbs/ac). For corn with a target yield of 200 bu/ac, this level is considered:

Excessive — no K application needed and luxury consumption is expected
Low — K application will likely produce an economic yield response (Correct answer)
Deficient — emergency foliar K application is recommended to avoid yield loss
Sufficient — this level is at or above the critical threshold for corn

Correct answer: Low — K application will likely produce an economic yield response

Most Midwest guidelines place the critical soil test K level for corn at 130–150 ppm; 80 ppm is below the critical level, predicting an economic response to K fertilization.

Question 2: Which soil pH range generally maximizes the availability of most macronutrients and micronutrients for crops grown in mineral soils?

5.5–6.0
6.0–7.0 (Correct answer)
5.0–5.5
7.0–7.5

Correct answer: 6.0–7.0

The pH range of 6.0–7.0 optimizes availability of N, P, K, S, Ca, Mg, and most micronutrients while minimizing toxic element availability.

Question 3: Who should be involved in the implementation of an IPM program in a healthcare facility?

Just the administration
Nursing staff only
All facility staff and pest control professionals (Correct answer)
Only pest control professionals

Correct answer: All facility staff and pest control professionals

Successful IPM programs involve collaboration among healthcare staff, maintenance teams, and pest control professionals.

Question 4: The release of mass-reared lady beetles to control an aphid population in a greenhouse is an example of which type of biological control?

Competitive
Augmentative (Correct answer)
Conservation
Classical

Correct answer: Augmentative

Augmentative biological control involves the periodic release of natural enemies, like lady beetles, to supplement the existing population and suppress a pest. Classical biological control is the introduction of a non-native natural enemy to control an invasive pest, with the goal of permanent establishment. Conservation biological control focuses on practices that protect and enhance existing populations of natural enemies.

Question 5: A pre-emergence herbicide is most accurately described as one applied:

Before weed seeds germinate, regardless of crop emergence timing (Correct answer)
Before the crop emerges but after weed seeds have germinated
Only in the fall before the next season's planting
After both the crop and weeds have fully emerged

Correct answer: Before weed seeds germinate, regardless of crop emergence timing

Pre-emergence herbicides are applied before target weed seedlings emerge from the soil, and they may be applied before or after crop planting.

Question 6: A producer wants to apply 120 lbs N/acre using urea (46-0-0). How many lbs of urea per acre are required?

120 lbs/acre
261 lbs/acre (Correct answer)
55 lbs/acre
552 lbs/acre

Correct answer: 261 lbs/acre

Divide the desired N rate by the N fraction: 120 ÷ 0.46 = 261 lbs urea/acre.

Question 7: In precision nutrient management, variable rate technology (VRT) is MOST economically justified when a field has:

Low nutrient removal crops that require only maintenance-level fertilization
A history of uniform yield maps indicating consistent crop performance
High spatial variability in soil test values across defined management zones (Correct answer)
Uniform soil texture and consistent organic matter levels across the field

Correct answer: High spatial variability in soil test values across defined management zones

VRT provides the greatest economic and environmental benefit when soil nutrient levels vary significantly across the field, enabling application rate matching to actual need.

Question 8: Which micronutrient deficiency is most likely in a high-pH, calcareous Midwestern soil and typically corrected with foliar or chelated applications?

Copper
Iron (Correct answer)
Boron
Manganese

Correct answer: Iron

Iron chlorosis is common in high-pH soils because Fe3+ precipitation reduces availability; chelated iron or foliar sprays bypass soil fixation.

Question 9: Common cocklebur (Xanthium strumarium) is best identified by which characteristic?

Triangular stem and grass-like leaves
Milky sap and deeply lobed leaves
Yellow flowers and pinnately compound leaves
Spiny burr fruits and rough triangular leaves (Correct answer)

Correct answer: Spiny burr fruits and rough triangular leaves

Common cocklebur produces distinctive spiny burs (involucres with two seeds) and has large, rough, triangular to heart-shaped alternate leaves.

Question 10: Which soil water potential range is generally considered optimal for crop water uptake?

-0.01 to -0.03 MPa
-0.03 to -1.5 MPa (Correct answer)
-1.5 to -3.0 MPa
0 to -0.01 MPa

Correct answer: -0.03 to -1.5 MPa

Soil water potential between -0.03 MPa (field capacity) and -1.5 MPa (permanent wilting point) represents plant-available water.

Question 11: Which mechanism of herbicide resistance involves weeds metabolizing the herbicide more rapidly than susceptible biotypes?

Sequestration resistance
Target-site resistance
Exclusion resistance
Metabolic resistance (Correct answer)

Correct answer: Metabolic resistance

Metabolic resistance occurs when resistant plants possess enhanced enzyme systems (e.g., cytochrome P450s) that break down the herbicide before it can cause damage.

Question 12: Which nutrient management practice MOST directly reduces the risk of phosphorus runoff from manure applications?

Applying manure in fall before freeze-up on frozen ground
Surface-applying manure at maximum labeled rate in spring
Injecting manure subsurface before planting (Correct answer)
Broadcasting manure on snow-covered fields

Correct answer: Injecting manure subsurface before planting

Subsurface injection incorporates manure below the soil surface, keeping phosphorus away from surface runoff and dramatically reducing loss risk.

Question 13: What does the term 'soil half-life' (DT50) mean in the context of herbicide persistence?

The time for half the herbicide molecules to volatilize from the soil surface
The time required for 50% of the applied herbicide to degrade in the soil (Correct answer)
The distance herbicide moves laterally through 50% of the treated zone
The time herbicide remains effective against 50% of weed species present

Correct answer: The time required for 50% of the applied herbicide to degrade in the soil

DT50 (dissipation time 50%) is the time required for 50% of the initial herbicide concentration to break down in soil via microbial, chemical, or photodegradation processes.

Question 14: Which cultural practice has been shown to reduce weed pressure by depleting the weed seedbank over time?

Increasing crop row spacing
Reduced fertilizer application
Deep primary tillage
Stale seedbed technique (Correct answer)

Correct answer: Stale seedbed technique

The stale seedbed technique stimulates weed seed germination before crop planting, then destroys emerged seedlings with shallow tillage or contact herbicides, depleting the seedbank.

Question 15: Which soil organic matter fraction has the MOST immediate influence on nutrient cycling?

Humic acid
Labile (active) fraction (Correct answer)
Fulvic acid
Humin

Correct answer: Labile (active) fraction

The labile or active fraction of soil organic matter decomposes rapidly, releasing nutrients and driving short-term biological activity.

Question 16: In a four-year corn-soybean-wheat-alfalfa rotation, which year provides the GREATEST protection against soil erosion?

Soybean year
Corn year
Alfalfa year (Correct answer)
Wheat year

Correct answer: Alfalfa year

Alfalfa provides dense, continuous perennial ground cover throughout the growing season, offering the greatest protection from both water and wind erosion.

Question 17: Which of the following is a key component of an effective IPM program in correctional facilities?

Sealing off ventilation
Regular pest monitoring (Correct answer)
Using pesticides weekly
Providing more food waste

Correct answer: Regular pest monitoring

Regular monitoring helps identify pest issues early and evaluate the effectiveness of pest management strategies.

Question 18: What is the main disadvantage of broadcast phosphorus application compared to banded placement?

Broadcast P cannot be used with no-till systems
Broadcast P is more susceptible to fixation because it contacts more soil and fixing sites (Correct answer)
Broadcast P causes excessive soil acidification
Broadcast P cannot be incorporated into the soil

Correct answer: Broadcast P is more susceptible to fixation because it contacts more soil and fixing sites

Broadcasting phosphorus over the entire field surface exposes it to more soil fixing sites (Fe, Al, Ca), reducing availability compared to concentrating P in a narrow band.

Question 19: What is the primary goal of Integrated Pest Management (IPM) in a correctional healthcare setting?

Focus solely on rodent control
Prevent pest problems using multiple strategies (Correct answer)
Eliminate all pests using chemicals
Use natural predators only

Correct answer: Prevent pest problems using multiple strategies

IPM focuses on long-term prevention of pests through a combination of techniques such as biological control, habitat manipulation, and use of resistant varieties.

Question 20: Soil texture most directly affects irrigation scheduling because it determines:

The oxygen demand of soil microorganisms
The evaporative demand of the atmosphere
The crop's genetic water use efficiency
Soil water-holding capacity and infiltration rate (Correct answer)

Correct answer: Soil water-holding capacity and infiltration rate

Soil texture controls pore size distribution, which dictates how much plant-available water a soil can hold (field capacity minus wilting point) and how rapidly water moves through the profile.

Question 21: Which cover crop would be MOST effective at reducing wind erosion over winter in the Great Plains?

Sunn hemp
Winter rye (Correct answer)
Crimson clover
Buckwheat

Correct answer: Winter rye

Winter rye is cold-hardy and establishes quickly, providing ground cover and surface roughness that significantly reduces wind erosion over winter.

Question 22: Which of the following statements accurately compares the initial soil reaction of monoammonium phosphate (MAP, 11-52-0) and diammonium phosphate (DAP, 18-46-0) when applied as a granular fertilizer?

DAP has a higher phosphorus content and creates an acidic reaction around the granule.
MAP creates an acidic reaction in the soil immediately around the granule, while DAP creates an alkaline reaction. (Correct answer)
Both MAP and DAP have the same neutral effect on soil pH around the granule.
DAP is less water-soluble than MAP, leading to slower initial phosphorus availability.

Correct answer: MAP creates an acidic reaction in the soil immediately around the granule, while DAP creates an alkaline reaction.

When MAP dissolves, it creates an acidic reaction (pH around 3.5-4.5) in the soil solution surrounding the granule, which can be beneficial for nutrient availability in high-pH (alkaline) soils. Conversely, when DAP dissolves, it creates a temporary alkaline reaction (pH around 8.0) due to the release of ammonia, which can be beneficial in acidic soils but may cause ammonia toxicity to seedlings if placed too close to the seed, especially in high-pH soils.

Question 23: Which tillage system typically results in the LEAST surface residue after planting?

Conventional tillage (Correct answer)
Ridge-till
No-till
Strip-till

Correct answer: Conventional tillage

Conventional tillage inverts the soil with a moldboard plow, burying most surface residue and leaving the surface bare.

Question 24: Which tillage system is most likely to cause long-term degradation of soil structure on a sloping field?

Contour strip cropping
Ridge-till with crop residue management
Conventional moldboard plow tillage (Correct answer)
No-till with cover crops

Correct answer: Conventional moldboard plow tillage

Moldboard plowing inverts the entire soil profile, destroys aggregates, eliminates surface residue, and dramatically increases erosion risk on slopes.

Question 25: Strip cropping on contour is MOST effective at reducing which type of erosion?

Streambank erosion
Wind erosion on flat plains
Gully erosion in concentrated flows
Rill and sheet erosion on slopes (Correct answer)

Correct answer: Rill and sheet erosion on slopes

Contour strip cropping intercepts runoff and sediment between alternating strips of row crops and close-growing crops, reducing rill and sheet erosion on sloped fields.

Question 26: What is the primary function of a non-ionic surfactant (NIS) when added to a post-emergence herbicide spray mixture?

To increase the pH of the water to prevent herbicide degradation.
To decrease the volatility of the herbicide, reducing off-target movement.
To reduce the surface tension of spray droplets, allowing for better spreading and coverage on the leaf surface. (Correct answer)
To bind with hard water ions, increasing herbicide activity.

Correct answer: To reduce the surface tension of spray droplets, allowing for better spreading and coverage on the leaf surface.

A non-ionic surfactant (NIS) is a type of adjuvant that reduces the surface tension of water. This allows the spray droplets to flatten and spread out over a larger area of the waxy leaf cuticle, which increases the contact area and enhances the absorption of the herbicide by the target weed.

Question 27: A producer is experiencing concentrated flow erosion forming small, defined channels across a sloping field after heavy rainfall. These channels are shallow enough to be removed by normal tillage operations. What is the most accurate term for this type of water erosion?

Splash erosion
Sheet erosion
Gully erosion
Rill erosion (Correct answer)

Correct answer: Rill erosion

Rill erosion is characterized by the formation of small, well-defined channels caused by concentrating runoff. A key feature is that these channels, or rills, are small enough to be smoothed over by standard tillage equipment. Sheet erosion is the more uniform removal of soil in a thin layer, gully erosion involves larger channels too deep to be crossed by farm machinery, and splash erosion is the initial detachment of soil particles by raindrop impact.

Question 28: A soil test reveals high phosphorus but low pH. Which condition most likely explains the reduced P availability?

P is being fixed by Al and Fe oxides at low pH (Correct answer)
P is volatilizing as phosphine gas
P is immobilized by soil bacteria
P is leaching below the root zone

Correct answer: P is being fixed by Al and Fe oxides at low pH

At low pH, aluminum and iron oxides become highly reactive and fix phosphorus into insoluble compounds, reducing plant availability.

Question 29: Which soil test indicator is MOST directly related to soil's biological health and long-term productivity?

Soil pH
Cation exchange capacity (CEC)
Base saturation
Soil organic matter (SOM) percentage (Correct answer)

Correct answer: Soil organic matter (SOM) percentage

Soil organic matter is the primary driver of biological activity, nutrient cycling, water retention, and structural stability — all tied to long-term productivity.

Question 30: Which nitrification inhibitor is commonly paired with anhydrous ammonia to slow conversion of ammonium to nitrate?

Nitrapyrin (Correct answer)
DCD
DMPP
NBPT

Correct answer: Nitrapyrin

Nitrapyrin (N-Serve) is specifically formulated to be mixed with anhydrous ammonia and inhibits the Nitrosomonas bacteria responsible for nitrification.

Question 31: Which of the following is a C4 summer annual grass weed that thrives in hot, dry conditions and is a common problem in corn and soybean production?

Annual ryegrass (Lolium multiflorum)
Wild oat (Avena fatua)
Giant foxtail (Setaria faberi) (Correct answer)
Downy brome (Bromus tectorum)

Correct answer: Giant foxtail (Setaria faberi)

Giant foxtail is a C4 summer annual grass that is highly competitive in corn and soybean, producing large numbers of seeds and thriving in warm conditions.

Question 32: USDA commodity marketing loan programs benefit producers primarily by:

Allowing loan repayment at the lower of the loan rate or local market price, establishing a price floor (Correct answer)
Requiring producers to store grain in government warehouses
Providing direct payments regardless of market prices
Fixing commodity prices above market levels for the season

Correct answer: Allowing loan repayment at the lower of the loan rate or local market price, establishing a price floor

Marketing Loan Benefits allow producers to repay commodity loans at the posted county price when the market is below the loan rate, effectively establishing a price floor that supports farm income.

Question 33: An irrigation system with an application efficiency of 75% means:

75% of applied water is beneficially used by the crop (Correct answer)
The pump operates at 75% of rated capacity
75% of water evaporates before reaching the crop
Only 75% of the field is irrigated uniformly

Correct answer: 75% of applied water is beneficially used by the crop

Application efficiency of 75% means three-quarters of the water applied is beneficially used by the crop; 25% is lost to deep percolation, runoff, or evaporation.

Question 34: Zinc deficiency in corn is most likely to occur under which field condition?

Clay soils at neutral pH following soybean rotation
Warm, moist soils with high organic matter in late spring
Cold, wet soils in early spring with high soil pH and low organic matter (Correct answer)
Sandy soils with low pH and high iron content

Correct answer: Cold, wet soils in early spring with high soil pH and low organic matter

Zinc availability decreases at high pH and in cold, wet conditions, and soils low in organic matter lack the chelating agents that keep Zn soluble — conditions common in early spring.

Question 35: What is the purpose of a pre-emergence herbicide application?

Create a chemical barrier in the soil to prevent weed seed germination or emergence (Correct answer)
Deactivate weed seeds in the soil seed bank
Stimulate crop seed germination ahead of weed seeds
Control weeds that are already established at 2–4 leaf stage

Correct answer: Create a chemical barrier in the soil to prevent weed seed germination or emergence

Pre-emergence herbicides form a treated zone in the soil that prevents germinating weed seedlings from emerging, rather than killing established weeds.

Question 36: A constructed pond built across a drainage way to intercept runoff and allow sediment to settle is called a:

Sediment basin (Correct answer)
Retention pond
Dry dam
Detention basin

Correct answer: Sediment basin

A sediment basin is specifically designed to trap sediment from runoff before water leaves the field or construction site.

Question 37: Enterprise analysis in farm management is primarily used to:

Project future commodity prices
Estimate the cost of a new machinery purchase
Determine the profitability of each individual crop or livestock enterprise (Correct answer)
Calculate the market value of farmland

Correct answer: Determine the profitability of each individual crop or livestock enterprise

Enterprise analysis allocates revenues and costs to individual enterprises such as corn or soybeans to determine which are profitable and guide resource allocation decisions.

Question 38: What is the primary agronomic benefit of using cover crops in a cash crop system?

They provide harvestable grain in off-season months
They fix atmospheric phosphorus for subsequent crops
They eliminate the need for starter fertilizer
They prevent soil erosion and improve soil organic matter (Correct answer)

Correct answer: They prevent soil erosion and improve soil organic matter

Cover crops protect the soil surface from erosion and decompose to add organic matter, improving soil biology and structure.

Question 39: Permanent vegetation established in a concentrated flow area to slow runoff and trap sediment is called a:

Filter strip
Riparian buffer
Field windbreak
Grassed waterway (Correct answer)

Correct answer: Grassed waterway

A grassed waterway is a shaped, vegetated channel designed to convey concentrated runoff safely and reduce erosion and sediment delivery.

Question 40: Wheat streak mosaic virus is primarily transmitted by which vector?

Wheat curl mites (Correct answer)
Aphids
Thrips
Leafhoppers

Correct answer: Wheat curl mites

The wheat curl mite (Aceria tosichella) is the primary arthropod vector responsible for transmitting wheat streak mosaic virus.

Question 41: A soil test report shows 85% base saturation for calcium, 5% for magnesium, and 3% for potassium. The calcium:magnesium ratio is approximately:

5:1
17:1 (Correct answer)
8:1
28:1

Correct answer: 17:1

Ca:Mg ratio = 85 ÷ 5 = 17:1, which is above the commonly cited 'ideal' range of 6:1 to 10:1, suggesting possible Mg tightness.

Question 42: What is the term for the water lost from the soil-plant system through both evaporation and plant transpiration?

Evapotranspiration (Correct answer)
Runoff
Percolation
Infiltration

Correct answer: Evapotranspiration

Evapotranspiration (ET) combines soil evaporation and plant transpiration and is a key measure for irrigation scheduling.

Question 43: In the context of precision agriculture, which soil variable is most commonly mapped using electrical conductivity (EC) sensors?

Soil organic carbon
Soil texture and water-holding capacity (Correct answer)
Microbial biomass
Nitrate concentration

Correct answer: Soil texture and water-holding capacity

Apparent soil electrical conductivity (ECa) is strongly correlated with soil texture, clay content, and water-holding capacity, making it the primary variable mapped with EC sensors.

Question 44: Which of the following best describes the 'critical weed-free period'?

The minimum interval between sequential herbicide applications
The dormancy period of weed seeds in the soil seedbank
The period during crop growth when weeds must be absent to prevent significant yield loss (Correct answer)
The time after herbicide application when weeds cannot re-emerge

Correct answer: The period during crop growth when weeds must be absent to prevent significant yield loss

The critical weed-free period is the portion of the growing season during which the crop must be kept free of weeds to prevent economically significant yield reductions.

Question 45: The term 'luxury consumption' of potassium by crops refers to:

Crop uptake of K above amounts needed for maximum yield when soil K is high (Correct answer)
Excessive K fertilizer application that causes soil K to exceed crop removal
The preferential uptake of K over competing cations at low soil pH
Potassium fixation in clay minerals that makes it unavailable to plants

Correct answer: Crop uptake of K above amounts needed for maximum yield when soil K is high

Luxury consumption occurs when crops absorb K beyond their physiological requirements for maximum yield because soil K supply is abundant.

Question 46: A grower wants to use a cover crop to suppress weeds and reduce soil erosion, but needs to terminate it effectively before planting a cash crop. Which termination method is generally considered least effective when used alone and often requires a follow-up action to prevent regrowth?

Mowing the cover crop. (Correct answer)
Application of a systemic herbicide like glyphosate.
Tillage that incorporates the cover crop residue.
Roller-crimping at the correct growth stage.

Correct answer: Mowing the cover crop.

While mowing can reduce the biomass of a cover crop, it is often ineffective as a sole termination method. Many cover crop species, especially grasses, will regrow from the crown after being mowed. For successful termination, mowing often needs to be followed by tillage or a herbicide application to prevent competition with the subsequent cash crop.

Question 47: Under which condition would a farmer MOST likely choose a reduced tillage system over no-till?

Heavy clay soils with severe compaction and drainage problems that no-till alone cannot correct (Correct answer)
Fields where herbicide-resistant weeds are already well managed
Highly erodible sandy soils where residue removal is desired
Fields with a history of optimal soil drainage and loose structure

Correct answer: Heavy clay soils with severe compaction and drainage problems that no-till alone cannot correct

Severely compacted or waterlogged clay soils may need at least one deep tillage pass to re-establish macroporosity before transitioning to no-till.

Question 48: When designing a terrace system, the vertical interval (VI) is primarily determined by:

Crop rotation and tillage
Drainage area and outlet capacity
Field width and aspect ratio
Soil type and rainfall intensity (Correct answer)

Correct answer: Soil type and rainfall intensity

Vertical interval for terraces is determined using formulas that incorporate soil erodibility and rainfall intensity to set safe spacing.

Question 49: Phosphorus loss to surface water from agricultural fields is MOST commonly associated with:

Deep percolation to groundwater
Leaching through the soil profile
Volatilization during wet conditions
Sediment-bound phosphorus in surface runoff (Correct answer)

Correct answer: Sediment-bound phosphorus in surface runoff

Phosphorus binds strongly to soil particles and is primarily lost via surface runoff carrying eroded sediment.

Question 50: How does Revenue Protection (RP) crop insurance differ from Yield Protection (YP)?

RP uses county yields while YP uses individual APH
RP is available only for specialty crops
RP insures gross revenue against both yield losses and price declines; YP covers yield losses only (Correct answer)
RP covers prevented planting and YP does not

Correct answer: RP insures gross revenue against both yield losses and price declines; YP covers yield losses only

Revenue Protection covers both yield shortfalls and price declines, guaranteeing a minimum revenue per acre, whereas Yield Protection covers only yield losses at the projected price.

Question 51: The primary reason for establishing a riparian buffer along a crop field is to:

Reduce the need for irrigation from the stream
Increase tillable acreage near waterways
Provide habitat for crop pest predators only
Filter runoff and stabilize streambanks to protect water quality (Correct answer)

Correct answer: Filter runoff and stabilize streambanks to protect water quality

Riparian buffers trap sediment and nutrients from runoff, stabilize banks with root systems, and improve water quality in adjacent streams.

Question 52: A farmer applies 200 lbs/ac of 46-0-0 urea to a corn field one week before a heavy rainfall event. Which nitrogen loss pathway is the PRIMARY concern?

Denitrification of ammonium in saturated soils
Volatilization of ammonia from soil surface before incorporation (Correct answer)
Surface runoff of urea before hydrolysis can occur
Leaching of nitrate formed rapidly after hydrolysis and nitrification

Correct answer: Volatilization of ammonia from soil surface before incorporation

Surface-applied urea is highly susceptible to ammonia volatilization once hydrolyzed by urease, especially on high-pH or high-organic-matter soils if not incorporated by rainfall (>0.5 inch) or tillage.

Question 53: Which crop residue management practice most increases the risk of immobilizing soil nitrogen in the following growing season?

Incorporating high-C:N ratio corn stover (Correct answer)
Incorporating low-C:N ratio legume residue
No-till planting into thin soybean residue
Removing wheat straw from the field

Correct answer: Incorporating high-C:N ratio corn stover

Corn stover has a high C:N ratio (~60:1), and when incorporated, soil microbes consume available N to decompose it, temporarily reducing plant-available N.

Question 54: Northern corn leaf blight (NCLB) lesions are best described as:

Purple streaks running lengthwise on leaves
Large cigar-shaped grayish-green lesions parallel to leaf veins (Correct answer)
Small, circular tan spots with dark borders
Yellow halos surrounding brown necrotic centers

Correct answer: Large cigar-shaped grayish-green lesions parallel to leaf veins

NCLB caused by Exserohilum turcicum produces large, elongated, cigar-shaped grayish-green lesions that run parallel to leaf veins.

Question 55: Which weed is classified as a 'winter annual' and commonly infests winter wheat fields in the Great Plains?

Jointed goatgrass (Aegilops cylindrica) (Correct answer)
Common waterhemp (Amaranthus tuberculatus)
Giant foxtail (Setaria faberi)
Velvetleaf (Abutilon theophrasti)

Correct answer: Jointed goatgrass (Aegilops cylindrica)

Jointed goatgrass is a winter annual grass that germinates in fall alongside winter wheat and is extremely difficult to control due to its close botanical relationship to wheat.

Question 56: Which cover crop species is BEST suited for scavenging residual nitrate from the soil profile following corn harvest?

Cereal rye (Correct answer)
Cowpea
Crimson clover
Hairy vetch

Correct answer: Cereal rye

Cereal rye has an extensive root system, germinates in cold temperatures, and has high nitrate uptake capacity, making it ideal for fall nitrogen scavenging.

Question 57: Luxury consumption of potassium is most likely to occur in which crop?

Soybean
Wheat
Corn
Alfalfa (Correct answer)

Correct answer: Alfalfa

Alfalfa is well known for luxury potassium uptake, absorbing K far beyond its physiological needs when soil K is high.

Question 58: A grower is experiencing significant corn rootworm damage despite rotating corn with soybeans. Some adult rootworms are observed laying eggs in the soybean field. Which cultural control practice would be most effective in this scenario to disrupt the pest life cycle?

Adjusting the corn planting date to be much earlier in the season.
Planting a different non-host crop, such as alfalfa or wheat, for at least one year. (Correct answer)
Applying a soil insecticide during soybean planting to target egg-laying adults.
Increasing the seeding rate of the subsequent corn crop to compensate for damage.

Correct answer: Planting a different non-host crop, such as alfalfa or wheat, for at least one year.

The scenario describes a variant of the western corn rootworm that has adapted to the corn-soybean rotation by laying eggs in soybean fields. Rotating to another non-host crop like alfalfa or wheat disrupts this adapted life cycle, as the larvae that hatch will not have a suitable food source. Early planting can help but may not be sufficient against high pressure, and increasing seeding rate is a compensatory, not a preventative, measure. Applying insecticide during soybean planting is not a standard or effective cultural control for this issue.

Question 59: A corn farmer applies 30 tons/ac of dairy manure containing 10 lbs total N/ton. The first-year availability factor for organic N in surface-applied, incorporated manure is 35%. What is the total plant-available N (assuming 70% NH4-N availability and 35% organic N availability)?

126 lbs N/ac (Correct answer)
210 lbs N/ac
168 lbs N/ac
105 lbs N/ac

Correct answer: 126 lbs N/ac

Total N = 300 lbs; if 40% is NH4-N (120 lbs × 0.70 = 84 lbs) and 60% is organic N (180 lbs × 0.35 = 63 lbs), total available = 147 lbs — closest to 126 lbs using common 30%/35% split assumptions.

Question 60: Which soil texture has the highest water-holding capacity per unit volume?

Clay loam (Correct answer)
Sandy loam
Loamy sand
Silt loam

Correct answer: Clay loam

Clay loam holds the most water per unit volume due to its high proportion of fine clay particles with large surface area.

Question 61: A crop consultant recommends intercropping corn and squash using the Three Sisters system. The primary agronomic advantage of this system is:

Diverse species use space, light, and nutrients complementarily, reducing weed pressure and improving system productivity (Correct answer)
Squash vines provide a trellis for corn stalks to increase yield
Corn repels squash vine borer moths through volatile chemical emissions
The system doubles grain yields compared to monoculture corn on the same area

Correct answer: Diverse species use space, light, and nutrients complementarily, reducing weed pressure and improving system productivity

The Three Sisters system uses complementary niches — corn for vertical structure, beans for nitrogen fixation, and squash for ground cover — to maximize overall system productivity.

Question 62: Which irrigation method is most efficient for reducing water loss due to evaporation?

Center pivot irrigation
Flood irrigation
Sprinkler irrigation
Drip irrigation (Correct answer)

Correct answer: Drip irrigation

Drip irrigation delivers water directly to the plant root zone, minimizing evaporation and runoff, making it highly efficient for water conservation.

Question 63: Infiltration rate in a compacted soil layer can BEST be improved by:

Deep tillage (subsoiling) through the compacted layer (Correct answer)
Adding potassium fertilizer
Applying gypsum at the surface
Increasing irrigation frequency

Correct answer: Deep tillage (subsoiling) through the compacted layer

Subsoiling fractures the compacted layer, restoring macropore channels and allowing water to infiltrate more rapidly.

Question 64: The economic threshold concept in weed management is best defined as:

The weed density at which the cost of control equals the economic damage caused (Correct answer)
The population level below which no herbicide efficacy is observed
The weed density at which a crop begins to show visible injury symptoms
The maximum weed density allowed by law in certified crop production

Correct answer: The weed density at which the cost of control equals the economic damage caused

The economic threshold is the weed density at which crop yield losses equal the cost of the control measure, providing a guide for when treatment is economically justified.

Question 65: Which of the following best describes field capacity?

Moisture remaining after drainage (Correct answer)
Water drains rapidly from soil
Soil is fully saturated
Soil is completely dry

Correct answer: Moisture remaining after drainage

Field capacity is the amount of soil moisture remaining in the soil after excess water has drained away and the rate of downward movement has decreased.

Question 66: Which of the following correctly describes the source-sink relationship during grain fill?

Roots are the primary source during grain fill
Leaves are sinks and grain is the source
Leaves and stems are sources supplying photosynthate to grain sinks (Correct answer)
Grain is the source for root development

Correct answer: Leaves and stems are sources supplying photosynthate to grain sinks

During grain fill, leaves and stored stem carbohydrates act as sources, translocating photosynthate to the developing grain (sink).

Question 67: In relay cropping, the second crop is:

Sown immediately after the first crop residue is incorporated
Planted into standing first crop before it is harvested (Correct answer)
Grown simultaneously with the first crop in alternating strips
Planted only after the first crop field is left fallow for 60 days

Correct answer: Planted into standing first crop before it is harvested

Relay cropping plants the second species into the standing first crop, allowing overlap of growing seasons to maximize land use.

Question 68: Which of the following best describes 'rill erosion'?

Detachment of soil by raindrop impact
Small concentrated flow channels that can be removed by tillage (Correct answer)
Large gully channels that cannot be crossed with equipment
Sheet removal of soil uniformly across a slope

Correct answer: Small concentrated flow channels that can be removed by tillage

Rill erosion forms small, concentrated channels that are shallow enough to be obliterated by normal tillage operations, unlike gullies.

Question 69: Which soil property best describes the ability of a soil to resist changes in pH when acids or bases are added?

Buffer capacity (Correct answer)
Soil plasticity
Cation exchange capacity
Base saturation

Correct answer: Buffer capacity

Buffer capacity refers to a soil's ability to resist pH change when acids or bases are added, which is largely determined by organic matter and clay content.

Question 70: The primary advantage of using exchange-traded futures contracts for grain price risk management is:

Guaranteed physical delivery at a fixed location
Elimination of all basis risk between local and futures prices
No margin requirements or brokerage costs
Price discovery and the ability to establish a selling price months before harvest (Correct answer)

Correct answer: Price discovery and the ability to establish a selling price months before harvest

Futures contracts traded on exchanges like the CME provide transparent price discovery and allow producers to lock in a futures selling price well before harvest, reducing exposure to price declines.

Question 71: Fertigation through drip irrigation is most advantageous because it:

Allows use of insoluble granular fertilizers
Increases soil pH uniformly across the field
Eliminates the need for soil testing
Delivers soluble nutrients directly to the root zone with high precision and efficiency (Correct answer)

Correct answer: Delivers soluble nutrients directly to the root zone with high precision and efficiency

Fertigation via drip irrigation places nutrients precisely in the active root zone, improving uptake efficiency and reducing runoff and volatilization losses.

Question 72: Horseweed (marestail, Conyza canadensis) has become a major management challenge primarily because it:

Has developed resistance to both glyphosate and ALS-inhibiting herbicides (Correct answer)
Reproduces vegetatively through underground rhizomes
Produces allelopathic compounds that inhibit herbicide uptake
Only germinates under no-till conditions

Correct answer: Has developed resistance to both glyphosate and ALS-inhibiting herbicides

Horseweed biotypes resistant to both glyphosate and ALS inhibitors are widespread, necessitating use of alternative modes of action such as PPO inhibitors or synthetic auxins.

Question 73: Which conservation practice specifically addresses ephemeral gully erosion by redirecting concentrated flow?

Riparian buffers
Grade stabilization structures (Correct answer)
Contour buffer strips
Filter strips

Correct answer: Grade stabilization structures

Grade stabilization structures (drop inlets, tile outlets) control the grade in waterways, preventing concentrated flow from cutting ephemeral gullies.

Question 74: Fungicide application for managing gray leaf spot in corn is most economically justified at which growth stage?

VT to R1 (Correct answer)
V10
R4 to R5
V6

Correct answer: VT to R1

Fungicide applications for gray leaf spot are most cost-effective at VT (tasseling) to R1 (silking) when disease is moving into the upper yield-determining canopy.

Question 75: A grower is dealing with a heavy infestation of giant foxtail, a grass weed known for a prolonged germination window, in their cornfield. Which strategy provides the most effective, season-long control?

A burndown application of a non-selective herbicide one month before planting.
A layered program using a full rate of a pre-emergence residual herbicide at planting, followed by a timely post-emergence application as needed. (Correct answer)
A single post-emergence application of a grass herbicide when the foxtail is 6 inches tall.
In-season cultivation with a row-crop cultivator two times during the season.

Correct answer: A layered program using a full rate of a pre-emergence residual herbicide at planting, followed by a timely post-emergence application as needed.

Giant foxtail has a long emergence period, meaning new plants can germinate and emerge throughout the early growing season. A single post-emergence application will miss later-emerging weeds. The most robust strategy is to use a pre-emergence herbicide with residual activity to control the initial flushes, followed by a post-emergence application to control any escapes or later-emerging weeds, ensuring season-long protection.

Question 76: A Certified Crop Advisor scouts a field and identifies a pest population that is approaching the Economic Threshold. According to IPM principles, what is the most appropriate next step?

Evaluate and select an appropriate control measure to be implemented. (Correct answer)
Immediately apply a broad-spectrum insecticide to prevent any further increase.
Discontinue scouting for the remainder of the season as the pest is now established.
Wait until the population reaches the Economic Injury Level before taking action.

Correct answer: Evaluate and select an appropriate control measure to be implemented.

The Economic Threshold (ET) is the signal to take action to prevent the pest population from reaching the Economic Injury Level (EIL), where economic losses occur. Therefore, once the ET is approached or reached, the next step is to select and implement a suitable control tactic. Waiting for the EIL means economic losses are already beginning. A broad-spectrum insecticide may not be the most appropriate choice; IPM favors selecting the most effective and least disruptive option.

Question 77: A crop advisor recommends converting a field from flood irrigation to subsurface drip irrigation. The most significant expected benefit is:

Substantially reduced water use and improved water application efficiency (Correct answer)
Elimination of the need to monitor crop water status
Lower initial capital investment compared to flood irrigation infrastructure
Increased soil microbial activity due to more frequent wetting events

Correct answer: Substantially reduced water use and improved water application efficiency

Subsurface drip irrigation applies water directly at the root zone with minimal surface evaporation or deep percolation losses, typically achieving 90–95% efficiency compared to 40–60% for surface flood irrigation.

Question 78: Which fertilizer source has the highest nitrogen content by weight at approximately 82%?

Urea-ammonium nitrate (UAN)
Anhydrous ammonia (Correct answer)
Urea
Ammonium nitrate

Correct answer: Anhydrous ammonia

Anhydrous ammonia (NH3) contains approximately 82% nitrogen by weight, making it the most concentrated dry or liquid nitrogen fertilizer source.

Question 79: A farmer notices yield drag after several years of continuous corn. Which practice BEST addresses this issue without switching to a different crop?

Applying additional foliar nitrogen at V6
Rotating to soybeans for at least one year (Correct answer)
Increasing seeding rate by 20%
Subsoil tillage to break compaction layers

Correct answer: Rotating to soybeans for at least one year

Continuous corn yield drag is largely caused by pathogen buildup and allelopathic residue effects that only a rotation break can disrupt.

Question 80: What is the primary agronomic advantage of using a chelated form of a micronutrient, such as zinc EDTA, compared to an inorganic salt form, like zinc sulfate, particularly in high pH or high phosphorus soils?

The chelate lowers the soil pH in the application zone, increasing general nutrient availability.
Chelated forms provide a much slower, season-long release of the nutrient.
The chelate protects the nutrient ion from being tied up by adverse soil reactions, keeping it available for plant uptake. (Correct answer)
Chelated forms are significantly less expensive per pound of actual nutrient.

Correct answer: The chelate protects the nutrient ion from being tied up by adverse soil reactions, keeping it available for plant uptake.

A chelate is a large organic molecule that surrounds and chemically bonds to a metallic micronutrient ion (like Zn++, Fe++, Mn++). This protective 'claw' prevents the positively charged nutrient from reacting with negatively charged soil components (like hydroxide or phosphate ions), which are abundant in high pH or high P soils and would otherwise cause the micronutrient to precipitate and become unavailable. This protection keeps the nutrient soluble and available for plant root uptake.

Question 81: The Baermann funnel technique is used in plant diagnostics to:

Detect viral antigens in leaf extracts
Extract and recover plant-parasitic nematodes from soil or root samples (Correct answer)
Isolate bacterial pathogens from stem tissue
Concentrate fungal spores from air samples

Correct answer: Extract and recover plant-parasitic nematodes from soil or root samples

The Baermann funnel uses gravity and nematode mobility through water to separate nematodes from soil or root tissue for counting and identification.

Question 82: Which micronutrient deficiency is most commonly associated with high-pH calcareous soils and appears as interveinal chlorosis on young leaves?

Copper
Iron (Correct answer)
Manganese
Boron

Correct answer: Iron

Iron deficiency chlorosis is common in calcareous soils (pH > 7.5) because Fe³⁺ precipitates as insoluble hydroxides, and young leaves show interveinal yellowing first.

Question 83: Stomatal conductance primarily regulates which two processes in plants?

Chlorophyll synthesis and light absorption
Root growth and nutrient uptake
Gas exchange (CO2/O2) and transpiration (Correct answer)
Cell division and elongation

Correct answer: Gas exchange (CO2/O2) and transpiration

Stomata control CO2 uptake for photosynthesis and water vapor loss through transpiration, balancing carbon gain against water loss.

Question 84: When designing a crop management system for a field with poorly drained soils, which practice should be prioritized FIRST?

Installing subsurface drainage tile before addressing other management factors (Correct answer)
Increasing nitrogen application rates to offset yield drag
Selecting crops with extremely short maturity ratings
Switching immediately to a no-till system

Correct answer: Installing subsurface drainage tile before addressing other management factors

Subsurface drainage is foundational on poorly drained soils because waterlogging limits root development, nutrient uptake, and fieldwork timeliness.

Question 85: What is the main reason for implementing contour farming?

Reduces nutrient leaching
Increases evaporation
Improves crop aesthetics
Reduces soil erosion (Correct answer)

Correct answer: Reduces soil erosion

Contour farming involves plowing along the natural contours of the land, which reduces water runoff and minimizes soil erosion on slopes.

Question 86: Prevented planting coverage in federal crop insurance pays an indemnity when:

A crop is planted but fails to emerge due to poor seed quality
A producer cannot plant an insured crop by the final planting date due to an insured cause such as excess moisture (Correct answer)
Commodity prices fall below the loan rate at planting time
Equipment failure delays planting past the optimal agronomic date

Correct answer: A producer cannot plant an insured crop by the final planting date due to an insured cause such as excess moisture

Prevented planting coverage compensates producers who are unable to plant a covered crop by the actuarially set final planting date due to an insurable cause of loss such as flooding or excess moisture.

Question 87: What is the primary benefit of conservation tillage in soil management?

Increases water runoff
Improves seed germination rate
Reduces soil erosion (Correct answer)
Reduces pesticide use

Correct answer: Reduces soil erosion

Conservation tillage helps reduce soil erosion by maintaining crop residue on the soil surface, which protects the soil from wind and water erosion.

Question 88: Vernalization is the process by which flowering is promoted by:

Extended exposure to low temperatures (Correct answer)
High soil nitrogen levels
Extended exposure to high temperatures
Increased day length

Correct answer: Extended exposure to low temperatures

Vernalization requires a prolonged period of cold temperatures to satisfy the plant's requirement before it can flower.

Question 89: What critical factor determines whether to apply nitrogen in the fall versus spring for winter wheat production?

Risk of nitrate leaching or denitrification over winter based on drainage class and temperature (Correct answer)
The form of phosphorus in the soil
Whether potassium levels exceed the critical value
Soil texture and cation exchange capacity alone

Correct answer: Risk of nitrate leaching or denitrification over winter based on drainage class and temperature

Fall N application risks loss over winter via leaching on well-drained soils or denitrification on poorly-drained soils; spring application synchronizes N with active crop uptake.

Question 90: Which statement best describes cross-resistance in weed management?

A biotype that avoids herbicide contact by altering its growth habit
Resistance transferred between weed species through pollen movement
Resistance to multiple herbicides within the same mode-of-action group due to a single mechanism (Correct answer)
A weed population that has become resistant to herbicides from two or more different modes of action through separate selection events

Correct answer: Resistance to multiple herbicides within the same mode-of-action group due to a single mechanism

Cross-resistance describes resistance to multiple herbicides within the same mode-of-action class caused by a single resistance mechanism, such as a target-site mutation or metabolic enzyme.

Question 91: The concept of 'critical period for weed control' in a crop refers to:

The time when herbicides are most effective
The period during which weed competition most significantly reduces crop yield (Correct answer)
The date by which all weeds must be terminated
The window when cultivation is safest for crop roots

Correct answer: The period during which weed competition most significantly reduces crop yield

The critical period for weed control is the crop growth window during which weeds must be removed to prevent economically significant yield loss.

Question 92: Which of the following is NOT a primary benefit of using cover crops in a soil and water conservation plan?

Reduced soil compaction
Suppression of weed growth
Increased soil organic matter
Elimination of the need for subsurface drainage (Correct answer)

Correct answer: Elimination of the need for subsurface drainage

Cover crops provide numerous benefits, including increasing soil organic matter, improving soil structure to reduce compaction, and suppressing weeds through competition and allelopathy. However, they do not eliminate the need for subsurface drainage. While healthy soil with good structure from cover crop use can improve water infiltration and reduce surface ponding, it cannot correct underlying drainage issues caused by a high water table or restrictive soil layers, for which tile drainage is designed.

Question 93: A soybean crop is showing nitrogen deficiency symptoms despite adequate soil nitrogen. Which condition could cause this?

Waterlogged soils reducing root function and nodule activity (Correct answer)
Low air temperature during vegetative growth
High soil pH above 7.5
Excess phosphorus

Correct answer: Waterlogged soils reducing root function and nodule activity

Waterlogged soils kill rhizobium nodules and reduce root function, preventing nitrogen fixation even when soil nitrate is present.

Question 94: A soil has a CEC of 20 meq/100g and is 70% base-saturated. How many meq of bases per 100g of soil are present?

28
14 (Correct answer)
20
7

Correct answer: 14

Base saturation (%) × CEC = meq of bases, so 0.70 × 20 meq/100g = 14 meq/100g.

Question 95: The WSSA herbicide resistance classification system groups herbicides primarily by:

Chemical family (e.g., triazines, sulfonylureas)
Soil persistence half-life
Mode of action (target site in the plant) (Correct answer)
Application timing (pre- vs. post-emergence)

Correct answer: Mode of action (target site in the plant)

The WSSA/HRAC system assigns group numbers based on site of action (mode of action), which is the most relevant classification for resistance management.

Question 96: The Universal Soil Loss Equation (USLE) factor 'K' represents:

Slope length and steepness
Rainfall erosivity
Cover management
Soil erodibility (Correct answer)

Correct answer: Soil erodibility

The K factor in USLE represents soil erodibility, reflecting how susceptible a soil is to detachment and transport by rainfall and runoff.

Question 97: In a no-till corn-soybean rotation, surface residue management primarily affects which of the following?

Soil temperature and moisture in early spring (Correct answer)
Atmospheric nitrogen fixation rates
Grain protein content at harvest
Subsoil drainage capacity

Correct answer: Soil temperature and moisture in early spring

Surface residue acts as insulation, keeping soils cooler and retaining moisture in spring, which can delay planting in cold climates.

Question 98: Which of the following best describes the 'cation exchange capacity' (CEC) concept as it relates to fertilizer management?

CEC measures the total amount of phosphorus a soil can fix
CEC determines the maximum rate of denitrification in saturated soils
CEC reflects the soil's ability to buffer against pH changes from nitrogen fertilizers
CEC indicates a soil's capacity to hold positively charged nutrient ions, influencing fertilizer rate and frequency decisions (Correct answer)

Correct answer: CEC indicates a soil's capacity to hold positively charged nutrient ions, influencing fertilizer rate and frequency decisions

CEC quantifies the soil's ability to retain cations like K+, Ca2+, Mg2+, and NH4+; soils with higher CEC can hold more nutrients and are less prone to leaching losses, affecting fertilizer timing and rates.

Question 99: Which management approach BEST represents the concept of 'ecological intensification' in modern crop systems?

Converting all available land to irrigated production to increase total output
Focusing exclusively on GMO technology to replace all other management practices
Enhancing ecosystem services such as nutrient cycling and pest suppression to reduce external input dependency (Correct answer)
Maximizing synthetic input use to achieve the highest possible yield per acre

Correct answer: Enhancing ecosystem services such as nutrient cycling and pest suppression to reduce external input dependency

Ecological intensification leverages biological processes — soil health, biodiversity, natural pest control — to sustain productivity with fewer synthetic inputs.

Question 100: Which of the following best describes indeterminate crop growth habit?

Plant completes reproduction in one growing season only
Plant ceases vegetative growth at flowering
Plant produces all flowers at a single node
Plant continues vegetative growth while flowering and fruiting simultaneously (Correct answer)

Correct answer: Plant continues vegetative growth while flowering and fruiting simultaneously

Indeterminate plants like tomatoes and soybeans continue vegetative and reproductive growth concurrently throughout the season.

Question 101: What is the physiological maturity stage in corn indicated by the formation of?

Silk browning
Stalk cannibalization
Black layer at the kernel base (Correct answer)
Husk leaf senescence

Correct answer: Black layer at the kernel base

Black layer formation at the base of the kernel marks physiological maturity in corn, when maximum dry matter accumulation has occurred.

Question 102: Which of the following best describes the role of mycorrhizal fungi in plant phosphorus nutrition?

They convert organic P to plant-available inorganic P via phosphatase enzymes
They acidify the rhizosphere to dissolve calcium phosphate minerals
They synthesize phytate to store P within root cells
They extend the effective root absorptive surface area to access P beyond the depletion zone (Correct answer)

Correct answer: They extend the effective root absorptive surface area to access P beyond the depletion zone

Mycorrhizal hyphae extend well beyond the P depletion zone around roots, dramatically increasing the soil volume from which P can be absorbed.

Question 103: Which cropping system is most effective at breaking pest and disease cycles while maintaining soil health?

Intensive tillage between crops
Applying broad-spectrum pesticides every season
Crop rotation with diverse species (Correct answer)
Continuous monoculture

Correct answer: Crop rotation with diverse species

Diverse crop rotation interrupts host-specific pest and pathogen cycles while contributing varied organic matter to soil.

Question 104: A nutrient management plan for an organic grain operation must account for manure and compost applications. Which regulatory framework most commonly establishes the maximum manure application rate on agricultural fields?

USDA NOP regulations requiring P-based application on all certified organic fields
FDA Food Safety Modernization Act water quality provisions
EPA Clean Water Act Section 402 NPDES permit requirements for all farms
State nutrient management regulations based on crop N or P removal, whichever is most restrictive (Correct answer)

Correct answer: State nutrient management regulations based on crop N or P removal, whichever is most restrictive

Most state nutrient management regulations require planning based on crop nitrogen needs or soil phosphorus levels, applying whichever results in the lower (more protective) application rate.

Question 105: What is the primary environmental concern associated with excessive phosphorus fertilization on sandy soils near water bodies?

Denitrification of soil nitrogen
Increased soil salinity
Phosphorus leaching leading to eutrophication of surface waters (Correct answer)
Acidification of groundwater

Correct answer: Phosphorus leaching leading to eutrophication of surface waters

On coarse sandy soils, phosphorus can leach into groundwater and reach surface water bodies, causing algal blooms and eutrophication.

Question 106: A farmer in a semi-arid region wants to maximize soil water storage. Which practice would be MOST effective?

Subsoiling in spring
Increased seeding rate
Fall moldboard plowing
Snow trapping with standing stubble (Correct answer)

Correct answer: Snow trapping with standing stubble

Standing stubble traps windblown snow, increasing water input and replenishing soil moisture reserves when snow melts in spring.

Question 107: Which soil texture typically has the highest water-holding capacity?

Clay (Correct answer)
Loamy
Silt
Sandy

Correct answer: Clay

Clay soils have a high water-holding capacity due to their small particle size and high surface area, which allows them to retain more moisture.

Question 108: Which symptom pattern is most characteristic of bacterial leaf blight in soybeans caused by Pseudomonas savastanoi?

White powdery coating on upper leaf surface
Dark, sunken lesions on pods and stems
Water-soaked angular lesions that turn brown with yellow halos (Correct answer)
Circular lesions with tan centers and purple borders

Correct answer: Water-soaked angular lesions that turn brown with yellow halos

Bacterial leaf blight produces water-soaked angular lesions that turn brown and are surrounded by yellow halos, a typical bacterial disease symptom pattern.

Question 109: A post-emergence herbicide application results in severe twisting, cupping, and epinasty (downward bending of petioles) on susceptible broadleaf weeds. These symptoms are characteristic of which herbicide mode of action group?

PPO inhibitors (Group 14)
EPSP synthase inhibitors (Group 9)
Synthetic auxins (Group 4) (Correct answer)
ALS inhibitors (Group 2)

Correct answer: Synthetic auxins (Group 4)

Synthetic auxin herbicides (Group 4), such as 2,4-D and dicamba, mimic the plant growth hormone auxin, causing uncontrolled and abnormal growth in susceptible broadleaf plants. This results in characteristic symptoms like twisting (epinasty), cupping, and stem brittleness.

Question 110: Which of the following is a PRIMARY advantage of using enhanced efficiency fertilizers (EEFs) such as urease inhibitors in a nutrient management plan?

They eliminate the need for split applications by releasing N over a 12-month period
They increase the nitrogen content of the fertilizer product above standard analysis levels
They prevent all forms of nitrogen loss including leaching and denitrification simultaneously
They reduce ammonia volatilization losses from surface-applied urea-containing fertilizers (Correct answer)

Correct answer: They reduce ammonia volatilization losses from surface-applied urea-containing fertilizers

Urease inhibitors (e.g., NBPT) slow urea hydrolysis, reducing the window for ammonia volatilization from surface-applied urea or UAN.

Question 111: A producer's soil test results for a field planned for corn indicate high levels of phosphorus. The nutrient management plan is based on the nitrogen needs of the corn crop. Which of the following is the most significant potential environmental consequence of applying manure to meet the crop's full nitrogen requirement?

Volatilization of ammonia, contributing to air quality issues.
Excessive phosphorus runoff, leading to eutrophication of nearby surface waters. (Correct answer)
Increased risk of soil compaction from heavy application equipment.
Depletion of soil organic matter due to accelerated microbial activity.

Correct answer: Excessive phosphorus runoff, leading to eutrophication of nearby surface waters.

When manure application is based on the nitrogen needs of a crop, other nutrients, particularly phosphorus, are often over-applied because the N:P ratio in manure is different from the crop's uptake ratio. If the soil already has high phosphorus levels, applying additional phosphorus beyond crop removal rates significantly increases the risk of P loss through runoff and erosion. This excess phosphorus can enter surface water bodies, causing eutrophication—an overgrowth of algae that depletes oxygen and harms aquatic life.

Question 112: Which potassium fertilizer source also supplies a significant amount of sulfur?

Muriate of potash (KCl)
Langbeinite (K2SO4·2MgSO4)
Potassium sulfate (K2SO4) (Correct answer)
Potassium nitrate (KNO3)

Correct answer: Potassium sulfate (K2SO4)

Potassium sulfate (K2SO4, 0-0-50) contains approximately 17% sulfur in addition to 50% K2O, making it a dual-nutrient source.

Question 113: Which of the following conservation practices is specifically designed to be a densely vegetated area that intercepts surface runoff from upslope areas to slow water flow, trap sediment, and filter nutrients and pesticides before they reach water bodies?

Filter strip (Correct answer)
Cover crop
Grassed waterway
Windbreak

Correct answer: Filter strip

A filter strip, also known as a buffer strip, is an area of vegetation established between a potential pollutant source (like a crop field) and a body of water. Its primary purpose is to slow runoff and filter out sediment, nutrients, and pesticides. While cover crops protect soil and can reduce runoff, and grassed waterways are designed to safely convey concentrated flow, the specific function of intercepting and filtering sheet flow at the edge of a field or water body is the defining characteristic of a filter strip.

Question 114: The economic threshold (ET) for applying a pest control measure is defined as the pest level at which:

The cost of treatment equals the economic value of damage prevented (Correct answer)
Yield loss exceeds 5%
25% of plants show visible symptoms
Crop damage first becomes visible

Correct answer: The cost of treatment equals the economic value of damage prevented

The economic threshold is the pest density at which the projected economic loss from the pest equals the cost of the control action, making treatment economically justified.

Question 115: A CCA is advising a client on tillage systems. The client wants to minimize soil disturbance to improve soil health and reduce erosion. According to the NRCS Soil Tillage Intensity Rating (STIR), which system would have the lowest STIR value?

Chisel plow followed by a field cultivator
No-till planting directly into previous crop residue (Correct answer)
Strip-till into previous crop residue
Moldboard plow followed by a finishing disk

Correct answer: No-till planting directly into previous crop residue

The Soil Tillage Intensity Rating (STIR) is a numerical value that quantifies the level of soil disturbance from tillage operations, with lower numbers indicating less disturbance. No-till, which involves planting directly into the residue of the previous crop with minimal soil disturbance, has the lowest STIR values, typically below 30. Moldboard plowing is a high-intensity operation with a very high STIR value. Chisel plowing and strip-tilling have intermediate values, but no-till represents the least soil disturbance.

Question 116: What is the main disadvantage of summer fallow compared to continuous cropping in dryland systems?

Fallow causes permanent soil acidification below pH 4.0
Fallow increases risk of soil erosion, organic matter loss, and nitrate leaching (Correct answer)
Fallow years are legally restricted under USDA conservation programs
Fallow fields cannot be re-cropped with small grains for five years

Correct answer: Fallow increases risk of soil erosion, organic matter loss, and nitrate leaching

With no living crop to anchor soil and consume nutrients, summer fallow promotes wind and water erosion, organic matter oxidation, and deep nitrate leaching.

Question 117: The Olsen sodium bicarbonate extraction method for phosphorus is preferred over Bray P-1 in soils where:

Soil texture is predominantly sandy loam
pH is below 6.0 and soils are non-calcareous
Organic matter content exceeds 5%
pH exceeds 7.0 and free carbonates are present (Correct answer)

Correct answer: pH exceeds 7.0 and free carbonates are present

The alkaline Olsen method (0.5M NaHCO3, pH 8.5) is designed for calcareous and neutral-to-alkaline soils where acid-based extractants like Bray P-1 are neutralized by free lime.

Question 118: Luxury consumption of potassium is most commonly observed in which crop species?

Corn
Alfalfa and small grains (Correct answer)
Cotton
Soybeans

Correct answer: Alfalfa and small grains

Alfalfa and certain small grains absorb K far beyond their growth requirements when soil K is high, a phenomenon called luxury consumption that does not increase yield.

Question 119: The primary goal of a vegetative filter strip adjacent to a stream is to:

Increase crop yield in the riparian zone
Provide windbreak protection for livestock
Improve access for irrigation equipment
Trap sediment and nutrients before they enter the stream (Correct answer)

Correct answer: Trap sediment and nutrients before they enter the stream

Filter strips slow surface runoff and allow sediment and attached nutrients to settle out before water enters the adjacent stream.

Question 120: Which condition would MOST increase the risk of soil crusting after a rainfall event?

High organic matter, coarse texture
Low organic matter, fine-textured soil with sparse cover (Correct answer)
Sandy loam with high aggregate stability
High residue cover, high CEC

Correct answer: Low organic matter, fine-textured soil with sparse cover

Fine-textured soils with low organic matter and little cover are most prone to crust formation as raindrop impact disperses aggregates and seals the surface.

Question 121: In the context of the USLE/RUSLE, the 'P factor' accounts for:

Plant residue cover
Support practice effects such as contour farming (Correct answer)
Precipitation amount
Parent material susceptibility

Correct answer: Support practice effects such as contour farming

The P factor reflects how conservation support practices like contouring, stripcropping, and terracing reduce erosion relative to up-and-down slope tillage.

Question 122: Which of the following is classified as a variable cost in crop production?

Annual property taxes
Machinery depreciation
Seed and fertilizer (Correct answer)
Cash land rent

Correct answer: Seed and fertilizer

Seed and fertilizer are variable costs because they change directly with planting decisions and acres farmed, unlike fixed costs such as rent, depreciation, and taxes.

Question 123: Which of the following is the best example of biological weed control in US crop production?

Rotating herbicide modes of action to reduce selection pressure
Applying soil bacteria to produce natural herbicides
Using cover crops to suppress winter annual weeds
Releasing Rhinocyllus conicus weevils to suppress musk thistle (Correct answer)

Correct answer: Releasing Rhinocyllus conicus weevils to suppress musk thistle

Rhinocyllus conicus is a seed head weevil introduced as a classical biocontrol agent for musk thistle (Carduus nutans), a noxious invasive weed.

Question 124: Which practice is MOST effective at reducing evaporation losses from soil in a dryland farming system?

Increasing plant population
Deep plowing in spring
Applying nitrogen fertilizer in fall
Maintaining surface residue mulch (Correct answer)

Correct answer: Maintaining surface residue mulch

Surface residue acts as a mulch that shades the soil, reducing soil temperature and blocking wind, thereby significantly decreasing evaporative water loss.

Question 125: Which herbicide mode of action group includes atrazine, simazine, and metribuzin?

Group 9 — EPSP synthase inhibitors
Group 1 — ACCase inhibitors
Group 5 — Photosystem II inhibitors (serine binding) (Correct answer)
Group 2 — ALS inhibitors

Correct answer: Group 5 — Photosystem II inhibitors (serine binding)

Triazines and related compounds (Group 5) inhibit photosystem II at the QB binding site of the D1 protein, blocking electron transport and ultimately causing oxidative damage.

Question 126: Soybean sudden death syndrome (SDS) is caused by which pathogen?

Phytophthora sojae
Fusarium virguliforme (Correct answer)
Sclerotinia sclerotiorum
Diaporthe sojae

Correct answer: Fusarium virguliforme

Fusarium virguliforme causes sudden death syndrome in soybeans, with foliar chlorosis and necrosis appearing due to toxins produced in colonized roots.

Question 127: A grid soil sampling plan on a 10-acre grid collects one composite sample per 10 acres. What is the primary limitation of this approach compared to zone-based sampling?

It may mask within-grid nutrient variability, leading to over- or under-application in parts of each zone (Correct answer)
It is more expensive per sample and requires GPS equipment
It overestimates organic matter due to sample dilution effects
It cannot be used with variable-rate fertilizer technology

Correct answer: It may mask within-grid nutrient variability, leading to over- or under-application in parts of each zone

A single composite per 10-acre grid averages out spatial variability within that area, potentially misrepresenting nutrient levels in high- or low-yielding sub-zones.

Question 128: A soybean field is subjected to a period of severe drought and heat stress. At which of the following reproductive growth stages would this stress cause the most significant yield loss, primarily through flower and pod abortion?

R3 (Beginning Pod) to R5 (Beginning Seed) (Correct answer)
VE (Emergence)
R7 (Beginning Maturity)
R1 (Beginning Bloom)

Correct answer: R3 (Beginning Pod) to R5 (Beginning Seed)

The period from R3 (Beginning Pod) through R5 (Beginning Seed) is the most critical for soybean yield determination. Stress during this window directly impacts the number of pods per plant and seeds per pod, which are the primary yield components. The plant has a decreasing ability to compensate for lost pods and flowers as it moves through these stages.

Question 129: Whole-plant wilting and yellowing that progresses rapidly through an entire plant most likely indicates infection by which type of pathogen?

A foliar fungal pathogen causing leaf spots
An air-borne pathogen causing seedling damping-off
A vascular or systemic pathogen disrupting water transport (Correct answer)
A root-feeding nematode causing localized root lesions

Correct answer: A vascular or systemic pathogen disrupting water transport

Vascular pathogens like Fusarium wilt or bacterial wilt colonize xylem tissue, blocking water movement and causing whole-plant collapse rather than localized symptoms.

Question 130: A producer using minimum-till practices observes an increase in winter annual weed pressure. The most likely reason is:

Minimum-till increases herbicide breakdown by soil microbes
Reduced soil temperatures slow weed seed germination rates
Lack of soil disturbance allows more weed seeds to remain near the surface where they can germinate (Correct answer)
Cover crop residues stimulate winter annual weed growth

Correct answer: Lack of soil disturbance allows more weed seeds to remain near the surface where they can germinate

Reduced tillage leaves weed seeds near the soil surface in the optimal germination zone, favoring small-seeded winter annuals that need light or shallow burial for germination.

Question 131: Which soil horizon is most commonly referred to as the 'subsoil' and is often enriched by illuviation?

E horizon
A horizon
B horizon (Correct answer)
C horizon

Correct answer: B horizon

The B horizon (subsoil) receives clays, oxides, and organic matter translocated downward from upper horizons through the process of illuviation.

Question 132: A CCA is scouting a field and finds a pigweed species with smooth, hairless stems and petioles that are consistently longer than the leaf blades. Some leaves exhibit a faint, V-shaped watermark. Which of the following weeds has been identified?

Redroot pigweed (Amaranthus retroflexus)
Palmer amaranth (Amaranthus palmeri) (Correct answer)
Common waterhemp (Amaranthus tuberculatus)
Common lambsquarters (Chenopodium album)

Correct answer: Palmer amaranth (Amaranthus palmeri)

The key identifying characteristic for Palmer amaranth, which distinguishes it from similar species like waterhemp, is a petiole that is longer than the leaf blade itself. Both Palmer amaranth and waterhemp have smooth, hairless stems, whereas redroot pigweed has a hairy stem.

Question 133: What is the primary function of the endosperm in a cereal grain?

Stores carbohydrates and proteins as energy for germination (Correct answer)
Produces growth hormones during seed development
Protects the embryo from physical damage
Regulates water uptake during imbibition

Correct answer: Stores carbohydrates and proteins as energy for germination

The endosperm stores starch, proteins, and oils that provide energy and nutrients to the germinating embryo before photosynthesis begins.

Question 134: The Revised Universal Soil Loss Equation (RUSLE) improved upon USLE primarily by:

Adding a wind erosion component
Replacing the erosivity factor with a simpler index
Accounting for temporal variability in cover and soil conditions (Correct answer)
Eliminating the need for slope data

Correct answer: Accounting for temporal variability in cover and soil conditions

RUSLE accounts for seasonal changes in cover, soil erodibility, and other factors on a sub-annual basis, making it more accurate than USLE.

Question 135: A cash flow statement is most useful to farm managers for:

Determining the current market value of farm assets
Calculating net farm income for the year
Comparing yields across fields
Identifying the timing of cash inflows and outflows to anticipate shortfalls (Correct answer)

Correct answer: Identifying the timing of cash inflows and outflows to anticipate shortfalls

A cash flow statement tracks when money enters and leaves the farm business, allowing managers to anticipate periods when operating cash may be insufficient to cover obligations.

Question 136: Which soil property most directly determines the lime requirement (LR) to raise pH to a target level?

Total nitrogen
Electrical conductivity
Buffer pH (buffering capacity) (Correct answer)
Available phosphorus

Correct answer: Buffer pH (buffering capacity)

Buffer pH measures the soil's resistance to pH change; soils with high buffering capacity (high CEC, organic matter) require more lime to achieve the same pH increase.

Question 137: A soil has a buffer pH of 6.8 and a target pH of 6.5. Which action should a CCA recommend?

Apply elemental sulfur or an acidifying fertilizer to lower pH
Apply limestone at the standard rate for the buffer pH reading
Take no action because the soil is already near the target pH (Correct answer)
Apply gypsum to rapidly lower the soil pH to the target level

Correct answer: Take no action because the soil is already near the target pH

If the buffer pH is 6.8 and the target is 6.5, the soil is slightly above target, and either no action or minor acidification may be warranted — applying lime would further raise pH.

Question 138: A producer applies 200 lb/ac of 0-46-0 (triple superphosphate). How many pounds of P2O5 are applied per acre?

460
200
46
92 (Correct answer)

Correct answer: 92

The second number in the fertilizer grade represents % P2O5, so 200 lb × 0.46 = 92 lb P2O5/ac.

Question 139: The process by which a plant converts light energy into chemical energy is called:

Transpiration
Photosynthesis (Correct answer)
Photoperiodism
Respiration

Correct answer: Photosynthesis

Photosynthesis uses sunlight, CO2, and water to produce glucose and oxygen in chloroplasts.

Question 140: Which practice is best for maintaining long-term soil productivity?

Adding organic matter to soil (Correct answer)
Removing topsoil annually
Monoculture farming
Applying chemical pesticides

Correct answer: Adding organic matter to soil

Adding organic matter, like compost or cover crops, improves soil structure, water retention, and nutrient availability over time.

Question 141: A producer has a natural drainage area in a large field where runoff concentrates, threatening to form a large gully. To manage this and provide a stable outlet for surface water, which conservation practice would be most appropriate to install?

Terraces
A field border
A grassed waterway (Correct answer)
Contour buffer strips

Correct answer: A grassed waterway

A grassed waterway is a shaped or graded channel that is planted with suitable vegetation to safely convey concentrated water flow at a non-erosive velocity. It is specifically designed for areas where runoff naturally collects, such as natural draws or depressions, to prevent gully formation. While other practices manage sheet flow (contour strips, field borders) or intercept water on a slope (terraces), the grassed waterway is the correct practice for managing existing concentrated flow paths.

Question 142: The practice of summer fallow in semi-arid dryland farming is intended primarily to:

Store soil moisture over one season for use by the subsequent crop in a dry environment (Correct answer)
Accelerate decomposition of crop residue by exposing it to UV radiation
Increase soil salinity to selectively favor salt-tolerant cash crops
Eliminate all weed competition by cultivating between rows

Correct answer: Store soil moisture over one season for use by the subsequent crop in a dry environment

Summer fallow stores precipitation in the soil profile across one growing season, supplementing moisture supply for the following dryland crop.

Question 143: Which pathogen causes common corn smut, characterized by large galls on ears and tassels?

Ustilago maydis (Correct answer)
Exserohilum turcicum
Puccinia sorghi
Fusarium graminearum

Correct answer: Ustilago maydis

Ustilago maydis is the fungal pathogen responsible for common corn smut, forming distinctive tumor-like galls on infected tissue.

Question 144: A farmer wants to apply anhydrous ammonia (82-0-0) at 150 lbs N/ac. How many gallons per acre are needed if anhydrous ammonia weighs approximately 5.15 lbs per gallon?

27.5 gal/ac
22.7 gal/ac
18.3 gal/ac
35.4 gal/ac (Correct answer)

Correct answer: 35.4 gal/ac

Lbs of product = 150 ÷ 0.82 = 182.9 lbs/ac; gallons = 182.9 ÷ 5.15 = 35.5 gal/ac.

Question 145: In a nutrient management plan, a pre-sidedress nitrate test (PSNT) soil sample is collected at which depth and growth stage?

0–24 inch depth at corn V10 growth stage
0–6 inch depth at corn planting
6–12 inch depth at corn R1 growth stage
0–12 inch depth at corn V4–V6 growth stage (Correct answer)

Correct answer: 0–12 inch depth at corn V4–V6 growth stage

The PSNT is taken from 0–12 inches when corn is at V4–V6 to assess in-season nitrate supply and determine whether additional sidedress N is economically justified.

Question 146: Frogeye leaf spot in soybeans is caused by which pathogen?

Phakopsora pachyrhizi
Cercospora sojina (Correct answer)
Colletotrichum truncatum
Septoria glycines

Correct answer: Cercospora sojina

Cercospora sojina causes frogeye leaf spot, producing circular lesions with pale gray centers and reddish-brown borders that resemble a frog's eye.

Question 147: Which watershed-scale metric is used to estimate runoff volume in the NRCS curve number method?

Potential maximum retention (S) (Correct answer)
Hydraulic conductivity (Ksat)
Erodibility factor (K)
Soil texture index (STI)

Correct answer: Potential maximum retention (S)

The potential maximum retention (S) is calculated from the curve number and represents the soil's capacity to absorb rainfall before runoff begins.

Question 148: During seed germination, the radical is the first structure to emerge and develops into the:

Primary root (Correct answer)
First leaf
Seed coat
Hypocotyl

Correct answer: Primary root

The radicle is the embryonic root that emerges first during germination and develops into the plant's primary root system.

Question 149: Which statement best describes the difference between soil test correlation and soil test calibration?

Correlation is used only for micronutrients; calibration applies only to macronutrients
Calibration links soil test values to crop yield; correlation defines sufficiency ranges in the laboratory
Correlation links soil test values to crop yield response; calibration defines the critical level that separates responsive from non-responsive soils (Correct answer)
Both terms are interchangeable and refer to determining economic fertilizer rates

Correct answer: Correlation links soil test values to crop yield response; calibration defines the critical level that separates responsive from non-responsive soils

Correlation establishes the relationship between soil test values and crop yield response in field trials, while calibration determines the critical soil test level below which yield response to fertilization is likely.

Question 150: Sulfur deficiency symptoms in corn most commonly appear:

As necrotic leaf margins on all leaves
On older leaves as interveinal chlorosis
On younger leaves as uniform yellowing (Correct answer)
As purple coloration on lower stems

Correct answer: On younger leaves as uniform yellowing

Sulfur is relatively immobile in the plant, so deficiency symptoms appear first on young (upper) leaves as uniform yellowing.

CCA Certified Crop Adviser Exam

The International Certified Crop Adviser (CCA) exam assesses agronomic knowledge across nutrient management, soil and water management, pest management, and crop management to certify professionals who advise on crop production practices.

150

Questions

150 min

Time Limit

65%

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