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Which element of the 4R Nutrient Stewardship framework addresses applying fertilizer where crop roots can best access it while minimizing environmental loss?

Right Source

Right Rate

Right Time

Right Place

to track

2026 Statistics

Key Facts: CPAg Exam

~55%

Per-Section Pass Rate

ASA candidate reports

Exam Sections

Nutrient / Soil & Water / Pest / Crop

150-250 hrs

Study Time

Recommended

$74,160

Median Soil/Plant Scientist Wage

BLS 2024 (SOC 19-1013)

5 years

Experience Required

Post-BS (MS/PhD substitutes)

$400+

Application Fee

ASA / ARCPACS

The CPAg (Certified Professional Agronomist) is the senior agronomy credential above the CCA, awarded by the American Society of Agronomy (ASA) through ARCPACS. It requires a BS in agronomy, five years of post-degree experience, a current International CCA certification, five professional references, and adherence to the ASA Code of Ethics. The BLS reports 37,600 soil and plant scientists and agricultural/food scientists (SOC 19-1013) earned a median wage of $74,160 in 2024, with top earners above $128,920 and 6% projected employment growth through 2034.

Sample CPAg Practice Questions

Try these sample questions to test your CPAg exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which element of the 4R Nutrient Stewardship framework addresses applying fertilizer where crop roots can best access it while minimizing environmental loss?

A.Right Source

B.Right Rate

C.Right Time

D.Right Place

Explanation: Right Place refers to fertilizer placement (banded, broadcast, incorporated, injected, side-dressed) so nutrients are positioned where roots can capture them and losses to runoff, leaching, and volatilization are minimized. Subsurface banding of P, for example, reduces runoff loss from no-till systems while improving early-season uptake.

2A Mehlich-3 soil test returns 18 ppm P on a silt loam with a target of 25 ppm for corn. If plow-layer bulk density is 1.3 g/cm3 to 6 inches, approximately how many lb P2O5/acre are needed just to build the soil test by 7 ppm (using the common rule of ~9 lb P2O5 per 1 ppm build)?

A.32 lb P2O5/acre

B.63 lb P2O5/acre

C.90 lb P2O5/acre (approximately)

D.180 lb P2O5/acre

Explanation: The widely used Midwest rule is that it takes about 9 lb P2O5/acre to raise soil test P by 1 ppm (Bray or Mehlich-3) in the plow layer. 7 ppm x 9 lb = ~63 lb to build, plus crop removal to maintain yield; most state tables round the total 'build + maintenance' recommendation to about 80-90 lb P2O5/acre for a 200 bu corn crop at this test level. Option C reflects the most common published build-plus-maintenance recommendation.

3Which nitrogen source carries the highest risk of ammonia volatilization when surface-applied to a warm, moist, high-pH soil with crop residue?

A.Ammonium sulfate

B.Urea without a urease inhibitor

C.Calcium nitrate

D.Anhydrous ammonia injected 6 inches deep

Explanation: Urea hydrolyzes to ammonium carbonate via urease enzymes concentrated on crop residue. On warm, moist, high-pH surfaces, the resulting NH4+ shifts to NH3 gas and volatilizes. Losses can exceed 30% of applied N within 7-10 days. A urease inhibitor (NBPT) or rapid incorporation/irrigation dramatically reduces this loss.

4What is the primary agronomic reason to split-apply nitrogen on corn rather than apply the full rate pre-plant?

A.To reduce fertilizer purchase costs

B.To synchronize N availability with peak crop demand and reduce leaching/denitrification losses

C.To allow a lower total N rate because late N is more efficient

D.To avoid the need for a urease inhibitor

Explanation: Corn N uptake peaks from V8 through R1 (roughly 60% of season-long uptake in a 4-6 week window). Delivering a portion of N as side-dress, Y-drop, or fertigation matches availability with demand, limits the time N spends as nitrate vulnerable to leaching (coarse soils) or denitrification (saturated soils), and generally improves N use efficiency by 5-15%.

5A tissue test from V6 corn shows K at 1.4% (sufficient range 1.7-2.5%) on a CEC 15 cmol/kg silt loam with K soil test 140 ppm. Which management decision is most defensible?

A.Apply 200 lb K2O/acre broadcast immediately to correct tissue deficiency

B.Ignore the tissue test because soil test K is adequate

C.Investigate root restriction, compaction, and dry topsoil before fertilizing - soil test is adequate and K uptake is diffusion-limited

D.Switch to a foliar K program for the rest of the season

Explanation: Soil test K of 140 ppm on a CEC 15 silt loam is adequate. Early-season tissue K deficiencies with adequate soil test most often reflect restricted root exploration due to compaction, shallow planting into cold soils, or dry topsoil reducing diffusion to roots. Correcting the physical limitation is the appropriate action; broadcast K2O will not immediately enter V6 corn tissue and wastes nutrient.

6Which cation has the greatest suppressive effect on magnesium uptake when present at very high concentrations on the exchange complex?

A.Calcium

B.Potassium

C.Sodium

D.Hydrogen

Explanation: Excess exchangeable K competes directly with Mg2+ for uptake at root membranes. Ratios with K:Mg exceeding about 5:1 (on an equivalent basis) can induce Mg deficiency, particularly in sandy soils and in forage systems where grass tetany is a concern in ruminants.

7A dairy producer applies 6,000 gal/acre of liquid dairy manure testing 25 lb total N, 10 lb P2O5, and 20 lb K2O per 1,000 gal. If 35% of total N is plant-available the first year, how much first-year available N is applied per acre?

A.52 lb N/acre

B.53 lb N/acre (25 * 6 * 0.35)

C.90 lb N/acre

D.150 lb N/acre

Explanation: Total N applied = 25 lb/1,000 gal x 6,000 gal = 150 lb N/acre. First-year plant-available N = 150 x 0.35 = 52.5 lb N/acre, which rounds to 53. Proper crediting of manure N requires using the manure analysis plus the appropriate first-year availability coefficient, which varies with manure type, incorporation, and season.

8Which micronutrient deficiency is most commonly induced by over-liming acidic sandy soils?

A.Boron

B.Manganese

C.Molybdenum

D.Chlorine

Explanation: Manganese availability decreases sharply as soil pH rises above 6.5, particularly in sandy soils with low total Mn. Over-liming to pH 7.0+ frequently induces Mn deficiency in soybean, small grains, and vegetable crops. Diagnostic symptom is interveinal chlorosis of young leaves.

9A CPAg recommends an MRTN-based nitrogen rate for corn instead of a yield-goal formula. Which statement best explains why?

A.MRTN always recommends higher N rates that maximize yield

B.MRTN incorporates regional response-to-N data and the price ratio of N to corn, giving the economically optimum N rate rather than a yield-goal prescription

C.MRTN ignores soil N credits from manure and legumes

D.MRTN is a free online tool and faster than yield-goal math

Explanation: The Maximum Return to Nitrogen (MRTN) approach, developed by the Corn Belt N Rate Guidelines working group, pools hundreds of on-farm response trials and uses the current N:corn price ratio to compute the rate that maximizes profit, not yield. Yield-goal formulas (bu/ac x 1.2) chronically over-recommend N because there is no fixed linear relationship between yield and economic optimum N.

10Which of the following soil test methods is most appropriate for measuring plant-available phosphorus in CALCAREOUS soils (free carbonates, pH > 7.3)?

A.Bray P1

B.Mehlich-3 (with correction)

C.Olsen (sodium bicarbonate) P

D.Morgan P

Explanation: Olsen P (0.5 M NaHCO3, pH 8.5) was developed specifically for calcareous soils because its buffered extractant does not dissolve Ca-phosphates that would artifactually inflate the test. Bray P1 acid extraction is neutralized by soil carbonates, producing falsely low values. Mehlich-3 is widely used but needs calibration corrections on high-pH, calcareous soils.

About the CPAg Exam

Senior-level agronomy credential for experienced professionals. Requires BS + 5 years experience AND current CCA certification. Four-section exam covers nutrient, soil/water, pest, and crop management at an advanced applied level.

Questions

200 scored questions

Time Limit

3 hours per section (4 sections)

Passing Score

Scaled score (criterion-referenced, Modified Angoff)

Exam Fee

$400 application + ~$235 per section (American Society of Agronomy (ASA) / ARCPACS)

CPAg Exam Content Outline

25%

Nutrient Management

4R stewardship, soil and tissue testing, advanced fertilizer recommendations, manure management, nutrient loss pathways

25%

Soil and Water Management

Soil physics and chemistry, erosion control, drainage, irrigation, water quality, salinity, conservation planning

25%

Integrated Pest Management

Weed, insect, disease, and nematode biology; thresholds; pesticide chemistry, modes of action, resistance management

25%

Crop Management

Cropping systems, crop physiology, variety and hybrid selection, precision agriculture, yield limiting factors

How to Pass the CPAg Exam

What You Need to Know

Passing score: Scaled score (criterion-referenced, Modified Angoff)
Exam length: 200 questions
Time limit: 3 hours per section (4 sections)
Exam fee: $400 application + ~$235 per section

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CPAg Study Tips from Top Performers

1Work straight from the International CCA Performance Objectives - every CPAg question maps to one of these statements

2Master the 4R Nutrient Stewardship framework (Right Source, Right Rate, Right Time, Right Place) - it anchors the Nutrient Management section

3Drill herbicide/insecticide/fungicide modes of action by WSSA, IRAC, and FRAC codes to answer resistance-management scenarios

4Use state extension bulletins (e.g., Cornell NRCCA, Purdue, Iowa State) for applied scenario practice

5Take full-length timed section practice tests and aim for 80%+ before scheduling; CPAg items are denser and more applied than CCA

Frequently Asked Questions

What is the CPAg exam pass rate?

ASA does not publish an official CPAg-specific pass rate, but candidates commonly report first-attempt pass rates around 55-60% per section, and cumulative pass rates climb above 80% when candidates retake one or two sections within the five-year window. Passing is determined by a criterion-referenced Modified Angoff method rather than a fixed percentage.

How is the CPAg different from the CCA?

The CCA (Certified Crop Adviser) is the entry-level credential requiring a 2-year degree plus experience. The CPAg (Certified Professional Agronomist) is the senior credential requiring a BS in agronomy, five years of post-degree experience, and a current International CCA certification. CPAg questions are more applied, scenario-heavy, and require deeper integration of the four subject areas.

Do I have to pass the CCA exam before taking the CPAg exam?

Yes. Every CPAg applicant must hold a current International CCA certification or pass the International CCA exam as part of the CPAg application. The two credentials share a common exam framework; CPAg adds the BS-degree, five-year experience, references, and ethics requirements.

How many questions are on the CPAg exam?

The CPAg/International CCA exam is divided into four sections (Nutrient Management, Soil and Water Management, Pest Management, Crop Management). Each section contains roughly 50 multiple-choice items for about 200 total questions. You have 3 hours per section and may take sections individually over a five-year window.

How long should I study for the CPAg exam?

Plan for 150-250 hours of focused study, typically spread over 4-8 months. Candidates usually review the International CCA Performance Objectives, state extension publications, university agronomy textbooks, and complete several hundred practice questions. Practicing scenario-based problems is critical because CPAg items emphasize applied decision-making.

How much does the CPAg exam cost?

The CPAg application fee is approximately $400 and includes the certification review and first year of dues. Exam sections (shared with the International CCA) run about $235 each if you are taking or retaking the International CCA exam. Total out-of-pocket costs typically range from $400 to $1,340 depending on how many sections you need to sit.

How do I maintain the CPAg credential?

CPAgs must complete 40 Continuing Education Units (CEUs) every two years across the four competency areas and ethics, plus pay annual dues and adhere to the ASA Code of Ethics. CEUs can be earned through ASA-approved conferences, university extension courses, and self-study modules.

What is the job outlook for agronomists?

The BLS groups agronomists within 'Soil and Plant Scientists' (SOC 19-1013) and 'Agricultural and Food Scientists,' reporting a 2024 median wage of $74,160 and top earners above $128,920. Employment is projected to grow 6% from 2024-2034. CPAg-credentialed agronomists routinely command premiums of 10-20% over uncertified peers in consulting, seed, fertilizer, and precision-ag roles.