CCA Certified Crop Adviser Exam — Questions and Answers

Question 1: Luxury consumption of potassium is most commonly observed in which crop species?

Cotton
Corn
Soybeans
Alfalfa and small grains (Correct answer)

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 2: 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?

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

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

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

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

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

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 5: Which factor is most important when choosing crops for correctional institution farming?

Color of the crop
Ease of harvesting only
Compatibility with local climate (Correct answer)
Crop popularity

Correct answer: Compatibility with local climate

Climate compatibility ensures the crop can thrive in the local conditions, reducing failure and resource waste.

Question 6: Common ragweed (Ambrosia artemisiifolia) and giant ragweed (Ambrosia trifida) are best distinguished by:

Leaf shape — common ragweed has deeply pinnately lobed leaves while giant ragweed typically has three to five palmate lobes (Correct answer)
Flower color — common ragweed has yellow flowers while giant ragweed has white flowers
Stem pubescence — common ragweed has smooth stems while giant ragweed has hairy stems
Seed production — common ragweed produces burr-like seeds while giant ragweed has smooth seeds

Correct answer: Leaf shape — common ragweed has deeply pinnately lobed leaves while giant ragweed typically has three to five palmate lobes

Common ragweed leaves are deeply pinnately dissected (fern-like), while giant ragweed leaves are large with three to five distinct palmate lobes, making leaf morphology the easiest identifier.

Question 7: What distinguishes precision agriculture from conventional crop management?

It applies inputs at variable rates based on within-field spatial variability (Correct answer)
It eliminates the need for soil testing
It relies solely on drone imagery for all management decisions
It requires organic certification for implementation

Correct answer: It applies inputs at variable rates based on within-field spatial variability

Precision agriculture uses GPS, sensors, and data analytics to apply inputs only where and in amounts they are needed across variable field zones.

Question 8: What is the primary benefit of using a soil test before fertilization?

It increases crop yield directly
It determines existing nutrient levels (Correct answer)
It eliminates the need for fertilization
It reduces equipment wear

Correct answer: It determines existing nutrient levels

Soil testing identifies nutrient levels and pH, helping ensure that fertilizer recommendations are both efficient and environmentally responsible.

Question 9: A producer practicing no-till farming on a field with heavy residue cover is planting corn into cool, moist soils. Which of the following is the most significant potential benefit of using a starter fertilizer in a 2x2 band placement?

Increased germination rates due to seed-placed nutrients.
Reduced risk of soil compaction from fertilizer application equipment.
Complete elimination of the need for in-season nitrogen applications.
Enhanced early-season vigor and nutrient uptake in unfavorable conditions. (Correct answer)

Correct answer: Enhanced early-season vigor and nutrient uptake in unfavorable conditions.

In no-till systems with heavy residue, soils are often cooler and wetter in the spring, which can slow root development and reduce nutrient mineralization and availability. Placing a starter fertilizer 2 inches to the side and 2 inches below the seed (2x2 placement) provides a concentrated band of essential nutrients like nitrogen and phosphorus that are readily accessible to the seedling's developing root system. This promotes enhanced early-season growth and vigor, helping the crop overcome the stressful cool, wet conditions.

Question 10: Which practice is MOST effective at reducing evaporation losses from soil in a dryland farming system?

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

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 11: A wheat field shows patches of purple-colored plants with delayed maturity. Phosphorus deficiency is suspected. What soil condition most likely caused this?

Excess calcium competing with phosphorus
High organic matter tying up phosphorus
High soil pH reducing phosphorus availability
Low soil temperature reducing phosphorus uptake by roots (Correct answer)

Correct answer: Low soil temperature reducing phosphorus uptake by roots

Low soil temperatures reduce root metabolic activity and phosphorus diffusion rates, causing temporary deficiency even when soil phosphorus levels are adequate.

Question 12: In a nutrient management plan, 'crop removal values' are used to estimate nutrient budgets. Which nutrient has the HIGHEST typical removal rate (lbs/bu) in corn grain?

Phosphorus (P2O5)
Potassium (K2O)
Nitrogen (Correct answer)
Sulfur

Correct answer: Nitrogen

Nitrogen removal in corn grain is approximately 0.67 lbs N/bu, substantially higher than P2O5 (0.37 lbs/bu) or K2O (0.27 lbs/bu) removal rates.

Question 13: What is the primary function of the endosperm in a cereal grain?

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

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 14: Why is organic matter important in soil?

Improves soil structure and fertility (Correct answer)
Reduces microbial activity
Decreases water infiltration
Increases soil compaction

Correct answer: Improves soil structure and fertility

Organic matter improves soil structure, increases nutrient availability, and enhances water retention, making it vital for soil health and productivity.

Question 15: A pre-emergence herbicide is most accurately described as one applied:

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

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 16: The nitrogen use efficiency (NUE) of most cereal crops typically falls within which range?

95–100%
80–90%
20–50% (Correct answer)
60–75%

Correct answer: 20–50%

NUE for cereals is commonly 20–50%, meaning the majority of applied N is lost through leaching, volatilization, denitrification, or immobilization.

Question 17: Which maturity group of soybeans would be most appropriate for production in the northern Corn Belt (Minnesota/Wisconsin)?

Maturity groups VIII–X
Maturity groups IV–V
Maturity groups 00–I (Correct answer)
Maturity groups VI–VII

Correct answer: Maturity groups 00–I

Maturity groups 00–I are adapted to short growing seasons in the northern Corn Belt where early fall frosts limit the season.

Question 18: In a comprehensive nutrient management plan (CNMP), which of the following components is critical for protecting water quality in environmentally sensitive areas?

An emergency action plan for spills and accidental discharges. (Correct answer)
The schedule for equipment maintenance and calibration.
A list of all farm employees and their responsibilities.
The marketing plan for the crops to be grown.

Correct answer: An emergency action plan for spills and accidental discharges.

A key purpose of a nutrient management plan is to minimize environmental impact. Environmentally sensitive areas, such as those near streams, wells, or sinkholes, require special protection. An emergency action plan is a critical component that outlines procedures to contain and manage spills or unexpected runoff, thereby preventing or minimizing the contamination of water resources.

Question 19: Which cultural practice has been shown to reduce weed pressure by depleting the weed seedbank over time?

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

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 20: 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 21: When designing a terrace system, the vertical interval (VI) is primarily determined by:

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

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 22: Which soil amendment is most appropriate for reclaiming a high-pH sodic soil when free calcium carbonate (lime) is already present?

Elemental sulfur (S) (Correct answer)
Agricultural lime (CaCO₃)
Gypsum (CaSO₄·2H₂O)
Calcium chloride (CaCl₂)

Correct answer: Elemental sulfur (S)

Elemental sulfur is oxidized to sulfuric acid by soil bacteria, which dissolves native lime and releases calcium to displace sodium without adding excess calcium that lime already provides.

Question 23: Which fertilizer source provides the most readily plant-available form of phosphorus?

Monoammonium phosphate (MAP) (Correct answer)
Colloidal phosphate
Bone meal
Rock phosphate (PR)

Correct answer: Monoammonium phosphate (MAP)

MAP is a highly water-soluble, processed phosphate fertilizer where phosphorus is immediately available to plants, unlike rock phosphate which requires acidic conditions to dissolve slowly.

Question 24: A soybean field with a history of sudden death syndrome (SDS) would BEST benefit from which management strategy?

Applying foliar fungicides at R3 stage
Increasing plant population to compensate for losses
Planting earlier to maximize pod set
Selecting SDS-tolerant varieties and improving soil drainage (Correct answer)

Correct answer: Selecting SDS-tolerant varieties and improving soil drainage

SDS is driven by Fusarium virguliforme infection favored in wet, compacted soils, so varietal tolerance and drainage are the primary management tools.

Question 25: Common cocklebur (Xanthium strumarium) is best identified by which characteristic?

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

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 26: 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?

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

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 27: Enhanced efficiency fertilizers (EEFs) are best defined as products that:

Acidify calcareous soils to improve P availability
Eliminate the need for secondary macronutrient additions
Reduce nutrient losses to the environment through controlled release or inhibitor technology (Correct answer)
Increase fertilizer N content above standard grades

Correct answer: Reduce nutrient losses to the environment through controlled release or inhibitor technology

EEFs include polymer-coated slow-release fertilizers, nitrification inhibitors, and urease inhibitors, all designed to reduce N loss to air and water.

Question 28: A field shows wheel-track compaction restricting root growth to the top 6 inches. Which management practice most directly addresses subsoil compaction?

Surface application of compost
Chisel plowing to 10 inches
Increasing nitrogen fertilizer rate
Subsoiling or deep ripping below the compacted layer (Correct answer)

Correct answer: Subsoiling or deep ripping below the compacted layer

Subsoiling or deep ripping mechanically fractures compacted layers below normal tillage depth, restoring root channels and water infiltration.

Question 29: Which environmental condition most consistently favors infection by foliar fungal pathogens?

Hot, dry days above 95°F
High UV radiation and low humidity
Cool to moderate temperatures with extended leaf wetness (Correct answer)
Freezing overnight temperatures followed by warm days

Correct answer: Cool to moderate temperatures with extended leaf wetness

Most foliar fungal pathogens require free moisture on leaf surfaces for spore germination and penetration, making cool to moderate temperatures with extended leaf wetness most conducive to infection.

Question 30: Split nitrogen applications for corn are primarily recommended to:

Increase soil pH uniformly across the field
Reduce phosphorus tie-up in the root zone
Maximize ammonia volatilization from the soil surface
Improve synchrony between N supply and crop N demand, reducing losses (Correct answer)

Correct answer: Improve synchrony between N supply and crop N demand, reducing losses

Splitting N applications aligns nutrient availability with peak crop uptake periods (V5–VT), reducing leaching and denitrification losses compared to a single pre-plant application.

Question 31: In the context of crop rotation, what is the main agronomic benefit of including a legume in the rotation?

Legumes produce allelopathic compounds that suppress weeds
Legumes release potassium from soil minerals
Legumes fix atmospheric nitrogen, reducing fertilizer needs for the following crop (Correct answer)
Legumes increase soil bulk density

Correct answer: Legumes fix atmospheric nitrogen, reducing fertilizer needs for the following crop

Legumes hosting rhizobium bacteria fix atmospheric nitrogen into plant-available forms, reducing nitrogen fertilizer requirements for subsequent crops.

Question 32: Which of the following best describes 'rill erosion'?

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

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 33: In wheat, the Zadoks scale stage Z65 (anthesis) is critical for yield because:

Maximum leaf area index is achieved at this stage
Fertilization of florets determines the number of kernels per spike (Correct answer)
Root development peaks at anthesis
Tiller death reduces plant density at this stage

Correct answer: Fertilization of florets determines the number of kernels per spike

At anthesis, pollen release and fertilization determine the number of kernels set per spike, a primary yield component in wheat.

Question 34: Which weed produces seeds with a pappus (feathery plume) that enables long-distance wind dispersal, making it a major challenge in perennial crops and roadsides?

Common lambsquarters
Canada thistle (Cirsium arvense) (Correct answer)
Common waterhemp (Amaranthus tuberculatus)
Velvetleaf (Abutilon theophrasti)

Correct answer: Canada thistle (Cirsium arvense)

Canada thistle seeds have a feathery pappus that allows them to travel miles on the wind, making containment difficult and spread into new areas common.

Question 35: What is the agronomic role of a nitrogen credit when corn follows soybeans in rotation?

Corn after soybeans requires more nitrogen than continuous corn due to residue competition
The rotation credit only applies in fields with sandy soils
Soybeans physically deposit nitrogen granules into the soil for corn roots to absorb
Soybean residue decomposition releases symbiotically fixed nitrogen that reduces corn's fertilizer requirement (Correct answer)

Correct answer: Soybean residue decomposition releases symbiotically fixed nitrogen that reduces corn's fertilizer requirement

Soybean residue contains high-N compounds from biological fixation that mineralize during decomposition, providing plant-available N for the following corn crop.

Question 36: The crop coefficient (Kc) used in reference ET-based irrigation scheduling primarily accounts for:

Differences in water use between a reference crop and the actual crop at various growth stages (Correct answer)
The efficiency of the irrigation delivery system
Soil water-holding capacity differences across fields
Precipitation probability during the growing season

Correct answer: Differences in water use between a reference crop and the actual crop at various growth stages

Kc adjusts reference ET (ETo) for a specific crop and growth stage, reflecting differences in canopy cover, root depth, and plant physiology compared to the reference (typically grass or alfalfa).

Question 37: When computing a nitrogen budget using the maximum return to nitrogen (MRTN) approach, the primary economic inputs are:

Soil nitrate test and irrigation history
Soil organic matter percentage and clay content
Yield goal and previous crop type only
Corn price and nitrogen fertilizer cost (Correct answer)

Correct answer: Corn price and nitrogen fertilizer cost

MRTN calculations identify the N rate that maximizes profit by comparing the cost of N fertilizer against the value of the resulting yield response.

Question 38: Which tillage system is most likely to cause long-term degradation of soil structure on a sloping field?

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

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 39: Denitrification is most likely to accelerate under which combination of conditions?

Warm, saturated soil with available carbon (Correct answer)
Warm, dry soil at field capacity
Cool, dry, well-aerated soil
Cold, flooded soil with low organic matter

Correct answer: Warm, saturated soil with available carbon

Denitrifying bacteria thrive when soils are warm, anaerobic (saturated), and have readily available carbon as an energy source.

Question 40: What is the purpose of integrated weed management?

To increase pesticide usage
To promote natural weed growth
To control weeds using multiple strategies (Correct answer)
To delay harvest time

Correct answer: To control weeds using multiple strategies

Integrated weed management combines mechanical, chemical, and cultural methods to effectively control weeds and protect crop yields.

Question 41: A corn crop yielding 200 bu/acre removes approximately how many pounds of nitrogen in the grain?

200 lbs N/acre
80 lbs N/acre
160 lbs N/acre (Correct answer)
120 lbs N/acre

Correct answer: 160 lbs N/acre

Corn grain contains roughly 0.8 lb N per bushel, so 200 bu × 0.8 = 160 lbs N removed in grain at harvest.

Question 42: A producer wants to apply 120 lbs N/acre using urea (46-0-0). How many lbs of urea per acre are required?

261 lbs/acre (Correct answer)
120 lbs/acre
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 43: Which herbicide class is best suited for POST-emergence control of grass weeds in broadleaf crops such as soybeans?

Graminicides — ACCase inhibitors (Group 1) (Correct answer)
Triazines (Group 5)
ALS inhibitors (Group 2)
Synthetic auxins (Group 4)

Correct answer: Graminicides — ACCase inhibitors (Group 1)

Graminicides (ACCase inhibitors) such as clethodim and sethoxydim selectively control grass weeds in broadleaf crops without injuring the crop.

Question 44: Biological nitrogen fixation in legume crops is carried out by:

Rhizobium bacteria living symbiotically in root nodules (Correct answer)
Mycorrhizal fungi that convert N2 to ammonium in the rhizosphere
Free-living cyanobacteria in the bulk soil solution
The crop plant itself using specialized leaf enzymes

Correct answer: Rhizobium bacteria living symbiotically in root nodules

Rhizobium and related genera form root nodules in legumes and convert atmospheric N2 to ammonia using the enzyme nitrogenase in a symbiotic exchange.

Question 45: What is the most common cause of 'salt burn' injury when starter fertilizer is placed too close to the seed?

High pH of the fertilizer solution
Toxic ammonia release from ammonium fertilizers
Rapid acidification of the soil around the seed
Osmotic stress as high fertilizer salt concentration draws water away from the seed (Correct answer)

Correct answer: Osmotic stress as high fertilizer salt concentration draws water away from the seed

High salt concentration from nearby fertilizer lowers the soil water potential, pulling water out of the germinating seed and root tissue through osmosis, causing injury.

Question 46: A producer using minimum-till practices observes an increase in winter annual weed pressure. The most likely reason is:

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

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

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

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 48: A farmer wants to reduce soybean cyst nematode (SCN) populations. Which practice is most effective long-term?

Apply nematicide every year
Increase seeding rate by 20%
Apply potassium fertilizer at high rates
Plant SCN-resistant varieties in rotation with non-host crops (Correct answer)

Correct answer: Plant SCN-resistant varieties in rotation with non-host crops

Rotating SCN-resistant varieties with non-host crops (e.g., corn) is the most sustainable and cost-effective long-term management strategy.

Question 49: Which of the following best describes the 'cation exchange capacity' (CEC) concept as it relates to fertilizer management?

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

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 50: 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?

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

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

Injecting manure subsurface before planting (Correct answer)
Surface-applying manure at maximum labeled rate in spring
Applying manure in fall before freeze-up on frozen ground
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 52: When writing a nutrient management plan under USDA NRCS Practice Standard 590, the plan must address which of the following?

Only nitrogen and phosphorus applications from commercial fertilizer sources
All plant nutrients applied from all sources including manure, biosolids, and fertilizer (Correct answer)
Nitrogen management only in fields designated as vulnerable groundwater areas
Phosphorus management only in fields adjacent to surface water bodies

Correct answer: All plant nutrients applied from all sources including manure, biosolids, and fertilizer

NRCS 590 requires that nutrient management plans address all nutrients from all sources—commercial fertilizers, manure, biosolids, and other amendments—to protect water quality.

Question 53: Which soil organic matter fraction has the MOST immediate influence on nutrient cycling?

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

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 54: Nitrogen in urea-ammonium nitrate (UAN) solution is present in which three forms?

Nitrate, nitrite, and ammonium
Urea, ammonium, and nitrate (Correct answer)
Urea, nitrate, and nitrite
Ammonium, nitrite, and organic N

Correct answer: Urea, ammonium, and nitrate

UAN solution contains urea-N (~50%), ammonium-N (~25%), and nitrate-N (~25%), giving it a blend of fast- and slower-release nitrogen fractions.

Question 55: Cation exchange capacity (CEC) is primarily influenced by soil texture and organic matter because both contribute:

Anion exchange capacity
Positively charged exchange sites
Neutral exchange buffering
Negatively charged exchange sites (Correct answer)

Correct answer: Negatively charged exchange sites

Clay minerals and organic matter carry net negative surface charges that attract and hold cations such as Ca²⁺, K⁺, and NH₄⁺.

Question 56: In precision nutrient management, variable rate technology (VRT) is MOST economically justified when a field has:

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

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

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

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

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

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 59: 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?

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

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 60: Which of the following is NOT considered a fundamental component of an Integrated Pest Management (IPM) program?

Use of economic thresholds to guide control decisions.
Integration of multiple control tactics (cultural, biological, chemical).
Scheduled, calendar-based pesticide applications. (Correct answer)
Regular monitoring and scouting of pest populations.

Correct answer: Scheduled, calendar-based pesticide applications.

A core principle of IPM is to move away from preventative, calendar-based spraying. Instead, actions are taken based on monitoring and economic thresholds, ensuring that controls are applied only when necessary. The other options are all essential elements of a robust IPM program.

Question 61: The '4R' nutrient stewardship framework stands for right source, right rate, right time, and:

Right place (Correct answer)
Right region
Right residue
Right rainfall

Correct answer: Right place

The 4R framework stands for Right Source, Right Rate, Right Time, and Right Place—collectively improving nutrient use efficiency and environmental stewardship.

Question 62: What is a major benefit of using crop rotation in correctional facility agriculture programs?

Increases pesticide resistance
Encourages monoculture
Prevents use of compost
Reduces pests and improves soil health (Correct answer)

Correct answer: Reduces pests and improves soil health

Crop rotation improves soil fertility and disrupts pest and disease cycles, promoting long-term crop productivity.

Question 63: Which of the following crops is classified as a C4 plant with higher photosynthetic efficiency under hot, dry conditions?

Corn (maize) (Correct answer)
Alfalfa
Soybean
Wheat

Correct answer: Corn (maize)

Corn is a C4 plant that uses a more efficient carbon fixation pathway, giving it a competitive advantage in hot, sunny, and water-limited environments.

Question 64: Which mechanism of herbicide resistance involves weeds metabolizing the herbicide more rapidly than susceptible biotypes?

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

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 65: Secondary macronutrient deficiency symptoms in crops often appear first on older leaves. Which of the following nutrients is MOST mobile in the phloem and therefore shows deficiency symptoms on older tissue?

Magnesium (Correct answer)
Calcium
Boron
Sulfur

Correct answer: Magnesium

Magnesium is highly mobile in the phloem and is reallocated from older to younger leaves under deficiency, causing interveinal chlorosis on lower leaves first.

Question 66: Which tillage system typically results in the LEAST surface residue after planting?

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

Correct answer: Conventional tillage

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

Question 67: To fulfill Koch's postulates and confirm that a microorganism causes a specific disease, which sequence of steps is required?

Culture on agar, spray on field, record results
Isolate, identify, inoculate healthy host, reisolate and re-identify the same organism (Correct answer)
Sequence DNA and compare to databases only
Observe, treat, and evaluate recovery

Correct answer: Isolate, identify, inoculate healthy host, reisolate and re-identify the same organism

Koch's postulates require isolating the putative pathogen, inoculating a healthy susceptible host to reproduce symptoms, then reisolating and confirming the same organism from the inoculated plant.

Question 68: The '4R' nutrient stewardship framework stands for applying the right nutrient at the right:

Rate, release, range, and record
Rate, runoff, row, and season
Rate, time, place, and source (Correct answer)
Rate, ratio, row, and residue

Correct answer: Rate, time, place, and source

The 4Rs are: right source, right rate, right time, and right place, forming the foundation of responsible nutrient management.

Question 69: When tank-mixing herbicides to broaden the weed control spectrum, which of the following compatibility concerns should always be checked first?

Whether both products are in the same herbicide resistance group
Whether both products require the same nozzle type for application
Whether both herbicides have identical soil half-lives
Physical and chemical compatibility between products, plus label-mandated jar tests (Correct answer)

Correct answer: Physical and chemical compatibility between products, plus label-mandated jar tests

Physical compatibility (e.g., precipitation, separation) and chemical antagonism or synergism should be evaluated via a jar test before field application; the label is the law for tank-mix guidance.

Question 70: 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)?

105 lbs N/ac
168 lbs N/ac
126 lbs N/ac (Correct answer)
210 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 71: What is the primary benefit of conservation tillage in soil management?

Reduces soil erosion (Correct answer)
Increases water runoff
Improves seed germination rate
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 72: Which of the following best defines the Economic Threshold (ET) in an Integrated Pest Management (IPM) program?

The lowest pest population density that will cause economic damage.
The maximum pest population that can be tolerated without any yield loss.
The pest density at which control measures should be applied to prevent the pest population from reaching the Economic Injury Level. (Correct answer)
The point at which pest damage is visible in the field, justifying the cost of scouting.

Correct answer: The pest density at which control measures should be applied to prevent the pest population from reaching the Economic Injury Level.

The Economic Threshold (ET), also known as the Action Threshold, is the point at which a pest population is projected to reach the Economic Injury Level (EIL) if no management action is taken. Therefore, it is the trigger point for implementing control measures to prevent economic loss.

Question 73: Which nutrient deficiency typically causes interveinal chlorosis in the young, newly emerging leaves of a crop?

Iron (Fe) deficiency (Correct answer)
Nitrogen (N) deficiency
Potassium (K) deficiency
Magnesium (Mg) deficiency

Correct answer: Iron (Fe) deficiency

Iron deficiency causes interveinal chlorosis in young leaves because Fe is immobile in the plant and cannot be remobilized from older tissues.

Question 74: What does the term 'soil half-life' (DT50) mean in the context of herbicide persistence?

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 for half the herbicide molecules to volatilize from the soil surface
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 75: 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
Detention basin
Dry dam

Correct answer: Sediment basin

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

Question 76: Which laboratory methods are commonly used to detect plant viruses in submitted samples?

Koch's postulates and agar plating
ELISA and PCR (Correct answer)
Nematode centrifugation
Baermann funnel extraction

Correct answer: ELISA and PCR

ELISA detects viral coat proteins immunologically while PCR amplifies viral nucleic acids; both are standard diagnostic tools for plant virus identification.

Question 77: Palmer amaranth (Amaranthus palmeri) is distinguished from other pigweeds primarily by:

Presence of spiny stems and alternate leaf arrangement
Its inability to develop herbicide resistance
Extremely rapid growth rate and petioles longer than the leaf blade (Correct answer)
Its preference for wet, poorly-drained soils

Correct answer: Extremely rapid growth rate and petioles longer than the leaf blade

Palmer amaranth can grow over 2 inches per day under ideal conditions and has characteristically long petioles that often exceed the length of the leaf blade.

Question 78: A farmer is transitioning a field from conventional tillage to a long-term no-till system. Which of the following is a key soil health benefit they can expect to see over time?

Increased soil bulk density in the upper soil profile.
A rapid decrease in soil pH requiring immediate lime application.
Reduced water infiltration rates due to surface crusting.
An accumulation of soil organic matter and improved soil structure. (Correct answer)

Correct answer: An accumulation of soil organic matter and improved soil structure.

No-till farming eliminates soil disturbance, allowing crop residues to remain on the surface. This leads to a gradual increase in soil organic matter as the residue decomposes. The lack of tillage also allows for the development of stable soil aggregates, macropores from root channels and earthworms, which improves soil structure, water infiltration, and overall soil health.

Question 79: A field scout identifies a broadleaf weed with alternate leaves, a taproot, and milky latex sap. Which weed is most likely present?

Pigweed (Amaranthus spp.)
Common dandelion (Taraxacum officinale) (Correct answer)
Common ragweed
Common lambsquarters

Correct answer: Common dandelion (Taraxacum officinale)

Common dandelion produces milky latex sap when stems or leaves are broken, and has a characteristic deep taproot with a basal rosette of leaves.

Question 80: Which soil texture typically has the highest water-holding capacity?

Loamy
Clay (Correct answer)
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 81: Which potassium fertilizer source also supplies a significant amount of sulfur?

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

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

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

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 83: What is a disadvantage of overusing chemical pesticides in a correctional facility?

Reduced cleaning time
Increased pest activity
More food options
Pest resistance and health hazards (Correct answer)

Correct answer: Pest resistance and health hazards

Excessive pesticide use can lead to pest resistance and pose health risks to humans, especially in confined environments.

Question 84: A farmer in a semi-arid region wants to maximize soil water storage. Which practice would be MOST effective?

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

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 85: What does the term '4Rs' refer to in nutrient stewardship?

Reduction, Regulation, Renewal, Recycling
Right source, Right rate, Right time, Right place (Correct answer)
Research, Results, Resources, Reporting
Right price, region, ratio, rate

Correct answer: Right source, Right rate, Right time, Right place

The 4Rs stand for Right source, Right rate, Right time, and Right place — principles for optimizing nutrient use and minimizing environmental impact.

Question 86: A field has a measured soil loss of 6 tons/acre/year and a T value of 4 tons/acre/year. This means:

The field does not need conservation treatment
Erosion is within the tolerable rate
The soil is gaining organic matter
Erosion exceeds the tolerable soil loss rate (Correct answer)

Correct answer: Erosion exceeds the tolerable soil loss rate

Since actual soil loss (6 T/ac/yr) exceeds the T value (4 T/ac/yr), the field is losing soil faster than it can be replaced and requires conservation measures.

Question 87: Which environmental condition most favors development of gray leaf spot in corn?

Low humidity and high wind speed
High humidity, warm nights, and reduced air circulation in dense canopies (Correct answer)
Early-season frost followed by warm temperatures
Cool, dry nights with warm days

Correct answer: High humidity, warm nights, and reduced air circulation in dense canopies

Gray leaf spot caused by Cercospora zeae-maydis thrives under prolonged periods of high humidity and warm temperatures, especially in dense canopies with poor air movement.

Question 88: Which irrigation method is most efficient for reducing water loss due to evaporation?

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

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

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

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

Slope length and steepness
Cover management
Rainfall erosivity
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 91: What does the leaf area index (LAI) represent in crop physiology?

Number of leaves per plant
Total leaf surface area per unit ground area (Correct answer)
Total root surface area per unit soil area
Ratio of leaf length to leaf width

Correct answer: Total leaf surface area per unit ground area

LAI is the ratio of total one-sided leaf area to the ground surface area beneath the crop canopy, reflecting light interception capacity.

Question 92: Which weed life cycle is generally the most difficult to control and eradicate from a field, primarily due to its ability to reproduce vegetatively from extensive underground structures?

Creeping perennials (Correct answer)
Summer annuals
Biennials
Winter annuals

Correct answer: Creeping perennials

Creeping perennials are the most difficult to control because they reproduce by both seed and vegetative structures like rhizomes, stolons, and tubers. Tillage can break up these structures and spread them, creating new plants. A single herbicide application may kill the top growth but often fails to translocate sufficiently to kill the entire extensive root and rhizome system, allowing the weed to regrow.

Question 93: What is the term for the process where fine clay particles move downward through the soil profile and accumulate in a lower horizon?

Illuviation (Correct answer)
Podzolization
Eluviation
Gleization

Correct answer: Illuviation

Illuviation is the process of deposition or accumulation of materials transported from upper horizons into a lower horizon, such as clay forming an argillic horizon.

Question 94: A farm balance sheet provides which type of financial information?

Annual profit and loss for the farm business
A schedule of loan principal payments
Monthly cash receipts and disbursements
Assets owned, liabilities owed, and net worth at a point in time (Correct answer)

Correct answer: Assets owned, liabilities owed, and net worth at a point in time

A balance sheet is a financial snapshot listing what the farm owns (assets), what it owes (liabilities), and the difference (net worth or equity) at a specific date.

Question 95: Which soil texture has the highest water-holding capacity per unit volume?

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

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 96: Which cover crop is most effective at scavenging residual soil nitrate and preventing winter leaching losses?

Hairy vetch
Crimson clover
Cereal rye (Correct answer)
Sunn hemp

Correct answer: Cereal rye

Cereal rye is a non-legume with extensive fibrous roots that rapidly takes up residual nitrate in fall and winter, preventing leaching losses.

Question 97: Which condition would MOST increase the risk of soil crusting after a rainfall event?

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

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

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

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

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

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 100: 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 101: A farmer applies 180 lb N/acre to corn but achieves only 60% of expected yield response. Denitrification is suspected. Which field condition most supports this diagnosis?

Highly alkaline soil above pH 8.5
Frozen soil at time of application
Clay soil that was saturated for more than 3 days after application (Correct answer)
Sandy soil with low organic matter

Correct answer: Clay soil that was saturated for more than 3 days after application

Denitrification converts nitrate to nitrogen gases under anaerobic conditions; saturated clay soils create ideal oxygen-depleted environments for denitrifying bacteria.

Question 102: What is the safest approach to pest control in patient areas?

Use of non-chemical methods (Correct answer)
Routine chemical spraying
Allowing pests to coexist
Installing more lighting

Correct answer: Use of non-chemical methods

Non-chemical controls, such as traps or sanitation improvements, reduce exposure risks for patients and staff.

Question 103: Crop lodging refers to:

The permanent displacement of plant stems from vertical to a prostrate position (Correct answer)
The death of crop plants due to freezing temperatures
The process of crop residue decomposition after harvest
The accumulation of water in crop fields after rainfall

Correct answer: The permanent displacement of plant stems from vertical to a prostrate position

Lodging occurs when plant stems or roots fail, causing plants to fall over, which reduces yield, harvest efficiency, and grain quality.

Question 104: The primary goal of a vegetative filter strip adjacent to a stream is to:

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

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 105: A farmer observes interveinal chlorosis on the newest, upper leaves of his soybean plants. The field has a soil pH of 7.8. Which nutrient deficiency is the most likely cause of these symptoms?

Iron (Fe) (Correct answer)
Magnesium (Mg)
Nitrogen (N)
Potassium (K)

Correct answer: Iron (Fe)

Iron (Fe) deficiency is commonly characterized by interveinal chlorosis (yellowing between the veins) on the youngest or uppermost leaves because iron is immobile within the plant. [9] This condition, often called iron deficiency chlorosis (IDC), is frequently observed in high pH (alkaline) soils, as high pH reduces the availability of iron for plant uptake. [9, 31] Nitrogen, potassium, and magnesium are mobile nutrients, so deficiency symptoms would typically appear first on the older, lower leaves. [10]

Question 106: Soybeans are classified as short-day plants. This classification means that the initiation of flowering is primarily triggered by which environmental cue?

A specific accumulation of Growing Degree Days.
The length of the uninterrupted dark period exceeding a critical threshold. (Correct answer)
The plant reaching a genetically predetermined height.
Soil moisture levels dropping below a certain percentage.

Correct answer: The length of the uninterrupted dark period exceeding a critical threshold.

Photoperiodism in short-day plants like soybeans is controlled by the length of the night. Flowering is induced when the period of uninterrupted darkness is longer than a critical minimum. While called 'short-day', it is the long night that actually triggers the hormonal response for reproduction.

Question 107: In a soil with a high sodium adsorption ratio (SAR), which physical problem is most likely to develop?

Increased aggregate stability
Increased macropore flow
Soil dispersion and loss of structure (Correct answer)
Elevated soil pH below 6.5

Correct answer: Soil dispersion and loss of structure

High SAR soils have sodium dominating exchange sites, which causes clay dispersion, aggregate breakdown, and dramatic reduction in hydraulic conductivity.

Question 108: A nutrient management plan for a corn-soybean rotation includes organic matter decomposition credits. If a field has 3.5% organic matter, what approximate annual nitrogen credit (lbs N/ac) from mineralization is used in most Midwest state guidelines?

20–35 lbs N/ac (Correct answer)
10–15 lbs N/ac
70–100 lbs N/ac
40–60 lbs N/ac

Correct answer: 20–35 lbs N/ac

Most Midwest guidelines credit approximately 20 lbs N/ac per 1% organic matter annually, so 3.5% OM yields roughly 20–35 lbs N/ac from mineralization.

Question 109: Which of the following is a liming material rather than a fertilizer, but is often applied to improve nutrient availability?

Potassium chloride
Gypsum (calcium sulfate)
Calcitic limestone (CaCO3) (Correct answer)
Triple superphosphate

Correct answer: Calcitic limestone (CaCO3)

Calcitic limestone is a liming material that raises soil pH, improving the availability of most macro and micronutrients rather than supplying large amounts of plant-available nutrients directly.

Question 110: In a four-year corn-soybean-wheat-alfalfa rotation, which year provides the GREATEST protection against soil erosion?

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

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 111: A soil test reports 45 ppm Bray P1 phosphorus. Using the Mehlich-3 extraction, what conversion factor is typically applied to compare results between the two methods?

The two methods are directly interchangeable with no conversion
Divide Mehlich-3 by 1.1 to get Bray P1 equivalent
Multiply Bray P1 by 2.0 to estimate Mehlich-3
Multiply Bray P1 by 1.1 to estimate Mehlich-3 (Correct answer)

Correct answer: Multiply Bray P1 by 1.1 to estimate Mehlich-3

Mehlich-3 P values are typically about 10% higher than Bray P1, so multiplying Bray P1 by approximately 1.1 gives a rough Mehlich-3 equivalent.

Question 112: Which of the following best describes field capacity?

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

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 113: What is the primary reason sulfur-coated urea releases nitrogen more slowly than uncoated urea?

The sulfur coating must degrade or crack before water can dissolve the urea (Correct answer)
Sulfur reacts with nitrogen to form stable compounds
Sulfur blocks urease enzyme activity indefinitely
Sulfur increases soil pH, slowing nitrification

Correct answer: The sulfur coating must degrade or crack before water can dissolve the urea

The sulfur coating acts as a physical barrier; as it weathers and cracks, water enters and dissolves the urea, releasing nitrogen gradually.

Question 114: Which soil horizon is most commonly referred to as the 'subsoil' and is often enriched by illuviation?

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

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

-1.5 to -3.0 MPa
-0.03 to -1.5 MPa (Correct answer)
-0.01 to -0.03 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 116: The primary reason for establishing a riparian buffer along a crop field is to:

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

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

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

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

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

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

25% of plants show visible symptoms
Yield loss exceeds 5%
The cost of treatment equals the economic value of damage prevented (Correct answer)
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 120: In cotton, the NAWF (Nodes Above White Flower) index is used to determine:

Number of fruiting branches
Cutout stage and timing for irrigation termination (Correct answer)
Plant height in nodes
Nitrogen deficiency severity

Correct answer: Cutout stage and timing for irrigation termination

NAWF declines as the season progresses; a NAWF of 5 indicates cutout, when new fruiting positions are no longer being set.

Question 121: Permanent vegetation established in a concentrated flow area to slow runoff and trap sediment is called a:

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

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 122: Iron chlorosis in soybeans on high-pH calcareous soils is best described as a deficiency of:

Plant-available iron due to limited solubility at high pH (Correct answer)
Iron fixed by soil microorganisms
Iron in the atmosphere surrounding roots
Total iron in the soil

Correct answer: Plant-available iron due to limited solubility at high pH

Calcareous soils contain ample total iron but at pH above 7.5 Fe³⁺ solubility drops dramatically, making it unavailable for plant uptake.

Question 123: A farmer plans to plant soybeans in a field that was previously in alfalfa for three years. When calculating the nitrogen fertilizer needs for the soybeans, how should the previous alfalfa crop be handled in the nutrient management plan?

Extra nitrogen fertilizer should be added to help break down the tough alfalfa residue.
The nitrogen contribution from the alfalfa should be ignored as soybeans fix their own nitrogen.
A nitrogen credit should be subtracted from the base fertilizer recommendation. (Correct answer)
The application rate should be based solely on the previous year's soybean yield data.

Correct answer: A nitrogen credit should be subtracted from the base fertilizer recommendation.

Nutrient management plans must account for all sources of nutrients, including those from previous crops. Legumes like alfalfa fix atmospheric nitrogen, and a significant amount of this nitrogen remains in the soil and becomes available to the following crop as the residue decomposes. This is known as a 'legume credit' and must be subtracted from the total nutrient requirement to avoid over-application of nitrogen fertilizer.

Question 124: Which marketing tool allows a grain producer to lock in a selling price for a crop before harvest?

Spot market sale at harvest
Forward cash contract (Correct answer)
Basis contract
Hedge-to-arrive contract

Correct answer: Forward cash contract

A forward cash contract is an agreement between a producer and a grain buyer to sell a specific quantity at a predetermined price for a set delivery date, eliminating price risk.

Question 125: A grower applies an ALS-inhibiting herbicide and achieves poor control. Testing reveals the target enzyme has a single amino acid substitution. This is an example of:

Target-site resistance (Correct answer)
Metabolic resistance
Reduced absorption resistance
Cross-resistance from detoxification

Correct answer: Target-site resistance

Target-site resistance occurs when a mutation in the herbicide's target enzyme reduces binding affinity, preventing effective inhibition at labeled rates.

Question 126: Infiltration rate in a compacted soil layer can BEST be improved by:

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

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 127: Which fertilizer application method is most appropriate for correcting zinc deficiency observed mid-season in corn?

Fall broadcast of zinc sulfate
Deep band placement of zinc oxide
Broadcast incorporation of zinc EDTA before planting
Foliar application of zinc sulfate or zinc chelate solution (Correct answer)

Correct answer: Foliar application of zinc sulfate or zinc chelate solution

Mid-season foliar application of soluble zinc sources provides rapid correction of zinc deficiency since root uptake is slow when soil conditions limit zinc availability.

Question 128: 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 129: 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?

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

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 130: Why is sanitation crucial in an IPM plan?

Makes the facility more comfortable
Discourages pests by removing attractants (Correct answer)
Improves air conditioning
Reduces staff workload

Correct answer: Discourages pests by removing attractants

Maintaining clean environments eliminates food and water sources that attract pests, thereby preventing infestations.

Question 131: Why is soil testing essential before planting crops?

Determines fertilizer needs (Correct answer)
Prevents seed contamination
Detects insect infestations
Improves irrigation accuracy

Correct answer: Determines fertilizer needs

Soil testing reveals pH and nutrient levels, guiding proper fertilization and improving plant health outcomes.

Question 132: Which cultural practice best reduces white mold (Sclerotinia stem rot) pressure in soybeans?

Narrow row spacing for faster canopy closure
High seeding rates to ensure stand
Wide row spacing to improve canopy airflow (Correct answer)
Early planting before apothecia develop

Correct answer: Wide row spacing to improve canopy airflow

Wide row spacing improves air movement through the canopy, reducing humidity and slowing ascospore infection by Sclerotinia sclerotiorum.

Question 133: The Baermann funnel technique is used in plant diagnostics to:

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

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

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

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 135: Why is phosphorus typically banded rather than broadcast?

It places nutrients close to developing roots (Correct answer)
It improves crop color
It enhances foliar absorption
It prevents leaching

Correct answer: It places nutrients close to developing roots

Phosphorus is relatively immobile in soil, so banding it near roots increases uptake efficiency, especially in early plant stages.

Question 136: Which cover crop would be MOST effective at reducing wind erosion over winter in the Great Plains?

Buckwheat
Sunn hemp
Crimson clover
Winter rye (Correct answer)

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 137: What is the main reason for implementing contour farming?

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

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

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

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

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

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 140: When applying potassium chloride (muriate of potash) to a chloride-sensitive crop, what is the best alternative potassium source?

Potassium permanganate
Potassium nitrate
Potassium bicarbonate
Potassium sulfate (Correct answer)

Correct answer: Potassium sulfate

Potassium sulfate (K2SO4) provides potassium without chloride and is preferred for chloride-sensitive crops like tobacco and some fruits.

Question 141: Phosphorus loss to surface water from agricultural fields is MOST commonly associated with:

Volatilization during wet conditions
Leaching through the soil profile
Deep percolation to groundwater
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 142: Leaf area index (LAI) is defined as:

Total one-sided leaf area per unit ground area (Correct answer)
The number of leaves per plant
The rate of leaf appearance per degree-day
The ratio of leaf length to leaf width

Correct answer: Total one-sided leaf area per unit ground area

LAI is the total one-sided area of leaf tissue per unit surface area of land, used to quantify canopy density.

Question 143: Which macronutrient is most prone to leaching below the root zone in coarse-textured, high-rainfall soils?

Phosphorus
Nitrate-nitrogen (Correct answer)
Calcium
Potassium

Correct answer: Nitrate-nitrogen

Nitrate (NO₃⁻) carries a negative charge and is repelled by negatively charged soil particles, making it highly mobile and susceptible to leaching.

Question 144: In the context of the USLE/RUSLE, the 'P factor' accounts for:

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

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

Small, circular tan spots with dark borders
Large cigar-shaped grayish-green lesions parallel to leaf veins (Correct answer)
Purple streaks running lengthwise on leaves
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 146: 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?

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

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 147: 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 148: What is the agronomic rationale for strip-till compared to no-till in corn production?

Strip-till requires more passes across the field than conventional tillage
Strip-till warms and dries a narrow seed zone while leaving residue between rows intact (Correct answer)
Strip-till eliminates all tillage operations
Strip-till is only used in sandy, low-residue soils

Correct answer: Strip-till warms and dries a narrow seed zone while leaving residue between rows intact

Strip-till disturbs only the narrow strip where seeds will be planted, creating a warmer, drier seedbed while conserving residue and reducing erosion between rows.

Question 149: Field bindweed (Convolvulus arvensis) is particularly difficult to control because it:

Produces abundant airborne seeds that contaminate large areas rapidly
Is resistant to all registered herbicide chemistries
Has an extensive deep root system with vegetative reproductive structures (Correct answer)
Only emerges late in the season after most herbicide windows have passed

Correct answer: Has an extensive deep root system with vegetative reproductive structures

Field bindweed has a deep, extensive root and rhizome system that can extend 20+ feet deep, enabling regrowth from fragments following tillage or herbicide application.

Question 150: The main purpose of a living mulch system in crop production is to:

Replace the need for herbicide applications entirely in all environments
Provide a harvestable forage crop simultaneously with the grain crop
Maintain a living ground cover between crop rows to suppress weeds and reduce erosion (Correct answer)
Increase cash crop seeding rates above normal recommendations

Correct answer: Maintain a living ground cover between crop rows to suppress weeds and reduce erosion

Living mulch keeps the soil covered with a low-growing species between crop rows, suppressing weeds and protecting soil from erosion.

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

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150 min

Time Limit

65%

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