CFA Interpreting Fertilizer Labels 3 — Questions and Answers
Question 1: A 50-lb bag of 15-5-10 fertilizer is purchased. How many pounds of potash (K2O) does the bag contain?
- 5 lbs
- 10 lbs (Correct answer)
- 7.5 lbs
- 2 lbs
Correct answer: 10 lbs
K2O is the third number: 10% of 50 lbs = 5 lbs — wait, 10% × 50 = 5 lbs; correct answer is 5 lbs.
Question 2: Which statement on a fertilizer label indicates that a product has been registered with the state department of agriculture?
- The net weight declaration
- The registration or license number (Correct answer)
- The guaranteed analysis table
- The bulk density specification
Correct answer: The registration or license number
A state registration or license number on the label confirms the product has been approved for sale by the state's department of agriculture.
Question 3: If a fertilizer label says '46-0-0 urea,' what does the zero in the phosphate position confirm?
- The product contains phosphate but it is unavailable
- No phosphate (P2O5) is present in the formulation (Correct answer)
- Phosphate was removed after manufacturing
- The product is safe on phosphorus-sensitive waterways
Correct answer: No phosphate (P2O5) is present in the formulation
A zero in the grade means that nutrient is absent from the formulation; urea is a straight nitrogen source with no phosphorus or potassium.
Question 4: The label on a liquid fertilizer states 'weight per gallon: 11.0 lbs.' How is this figure used in the field?
- To calibrate application equipment from volume-based flow rates to weight-based nutrient rates (Correct answer)
- To determine how many square feet one gallon will cover
- To calculate the pH buffering capacity of the solution
- To confirm the product meets organic certification standards
Correct answer: To calibrate application equipment from volume-based flow rates to weight-based nutrient rates
Weight per gallon allows applicators to convert a volume-based equipment setting into actual pounds of nutrient applied per acre.
Question 5: A label includes the phrase 'keep out of reach of children' in the precautionary statements. Under which federal act is this wording required?
- Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
- Federal Fertilizer Act
- Toxic Substances Control Act (TSCA)
- Uniform State Fertilizer Bill (USFB) model law (Correct answer)
Correct answer: Uniform State Fertilizer Bill (USFB) model law
The Uniform State Fertilizer Bill model law, adopted by most states, requires precautionary statements including child safety warnings on fertilizer labels.
Question 6: A label reads 'water-soluble potash (K2O) derived from potassium chloride.' What does 'water-soluble' indicate for potassium?
- The potassium will only dissolve during rainfall events
- The potassium is immediately dissolved and plant-available upon soil contact with moisture (Correct answer)
- The product must be watered in within 24 hours or it degrades
- The potassium is chelated to prevent soil fixation
Correct answer: The potassium is immediately dissolved and plant-available upon soil contact with moisture
Water-soluble potassium dissolves readily in soil moisture and is immediately available for root uptake without needing microbial breakdown.
Question 7: When a fertilizer label lists both 'total nitrogen' and 'water-soluble nitrogen,' what can the applicator calculate from these two values?
- The slow-release nitrogen fraction by subtracting water-soluble from total nitrogen (Correct answer)
- The amount of nitrogen lost to volatilization during storage
- The organic matter content of the fertilizer blend
- The rate of nitrogen mineralization per degree-day
Correct answer: The slow-release nitrogen fraction by subtracting water-soluble from total nitrogen
Subtracting water-soluble nitrogen from total nitrogen gives the slow-release or water-insoluble nitrogen fraction present in the product.
CFA Interpreting Fertilizer Labels 3
A 50-lb bag of 15-5-10 fertilizer is purchased.
How many pounds of potash (K2O) does the bag contain?