Free CFA Label Interpretation and Calculations Questions and Answers 1 — Questions and Answers
Question 1: An applicator has a 50-pound bag of granular fertilizer with a guaranteed analysis of 24-6-12. How many pounds of actual nitrogen (N), phosphate (P2O5), and potash (K2O) are in the bag?
- 9.0 lbs N, 4.5 lbs P2O5, 7.5 lbs K2O
- 12.0 lbs N, 3.0 lbs P2O5, 6.0 lbs K2O (Correct answer)
- 24.0 lbs N, 6.0 lbs P2O5, 12.0 lbs K2O
- 50.0 lbs N, 6.0 lbs P2O5, 12.0 lbs K2O
Correct answer: 12.0 lbs N, 3.0 lbs P2O5, 6.0 lbs K2O
The three numbers in the guaranteed analysis represent the percentage by weight of N, P2O5, and K2O. To find the pounds of each nutrient, multiply the total weight of the bag (50 lbs) by the percentage of each nutrient in decimal form. Nitrogen: 50 lbs * 0.24 = 12.0 lbs. Phosphate: 50 lbs * 0.06 = 3.0 lbs. Potash: 50 lbs * 0.12 = 6.0 lbs.
Question 2: A soil test recommends applying 90 lbs of phosphate (P2O5) per acre. The applicator will use diammonium phosphate (DAP), which has a fertilizer grade of 18-46-0. How many pounds of DAP are needed to apply to one acre to meet the recommendation?
- 41.4 lbs
- 195.7 lbs (Correct answer)
- 90.0 lbs
- 500.0 lbs
Correct answer: 195.7 lbs
The formula to determine the amount of fertilizer needed is: (Recommended rate of nutrient) / (Percentage of nutrient in fertilizer as a decimal). In this case, 90 lbs of P2O5 is needed, and DAP contains 46% P2O5. Calculation: 90 lbs / 0.46 = 195.65 lbs, which rounds to 195.7 lbs.
Question 3: An applicator is using a liquid fertilizer, 32-0-0 Urea Ammonium Nitrate (UAN), which has a density of 11.06 lbs per gallon. How many pounds of actual nitrogen are in a 30-gallon tank of this product?
- 9.6 lbs
- 96.0 lbs
- 105.8 lbs (Correct answer)
- 331.8 lbs
Correct answer: 105.8 lbs
First, calculate the total weight of the liquid fertilizer: 30 gallons * 11.06 lbs/gallon = 331.8 lbs. Next, calculate the pounds of actual nitrogen by multiplying the total weight by the percentage of nitrogen: 331.8 lbs * 0.32 = 106.176 lbs. The closest answer is 105.8 lbs.
Question 4: The guaranteed analysis on a fertilizer label (e.g., 10-20-10) legally represents the minimum percentage by weight of which three nutrients in order?
- Elemental Nitrogen (N), Elemental Phosphorus (P), Elemental Potassium (K)
- Ammoniacal Nitrogen (N), Soluble Phosphorus (P), Liquid Potash (K)
- Total Nitrogen (N), Available Phosphate (P2O5), Soluble Potash (K2O) (Correct answer)
- Organic Nitrogen (N), Bone Phosphate (P2O5), Muriate of Potash (K2O)
Correct answer: Total Nitrogen (N), Available Phosphate (P2O5), Soluble Potash (K2O)
By law, the three numbers in the guaranteed analysis on a fertilizer label represent the minimum percentage by weight of Total Nitrogen (N), Available Phosphate (P2O5), and Soluble Potash (K2O), in that specific order.
Question 5: A turf manager needs to apply 0.9 lbs of actual Nitrogen per 1,000 sq. ft. They are using a fertilizer with an analysis of 21-0-7. How many pounds of this fertilizer product must be applied to a 6,000 sq. ft. lawn area?
- 4.3 lbs
- 12.6 lbs
- 25.7 lbs (Correct answer)
- 37.8 lbs
Correct answer: 25.7 lbs
First, determine the amount of fertilizer product needed per 1,000 sq. ft. by dividing the target nitrogen rate by the nitrogen percentage: 0.9 lbs N / 0.21 = 4.286 lbs of product per 1,000 sq. ft. Second, scale this amount for the total area: 4.286 lbs/1,000 sq. ft. * 6 (since the area is 6,000 sq. ft.) = 25.716 lbs.
Question 6: Which of the following pieces of information, sometimes found on a fertilizer label, indicates the amount of limestone required to neutralize the long-term acidifying effect of one ton of the fertilizer?
- Salt Index
- Bulk Density
- Potential Acidity (Correct answer)
- Derived From Statement
Correct answer: Potential Acidity
Potential Acidity, often expressed as Calcium Carbonate Equivalent (CCE), is a value on some fertilizer labels that quantifies the material's tendency to lower soil pH over time. It represents the number of pounds of calcium carbonate (limestone) needed to offset the acidity produced by one ton of the fertilizer.
Free CFA Label Interpretation and Calculations Questions and Answers 1
An applicator has a 50-pound bag of granular fertilizer with a guaranteed analysis of 24-6-12.
How many pounds of actual nitrogen (N), phosphate (P2O5), and potash (K2O) are in the bag?