Interpreting Fertilizer Labels Flashcards
7 cards from real CFA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Interpreting Fertilizer Labels flashcards as text
A label shows 'total nitrogen 21%, of which 14% is slowly available from isobutylidene diurea (IBDU).' What condition most affects IBDU release rate?
Answer: Soil moisture
IBDU breaks down primarily through hydrolysis, so soil moisture — not temperature or microbial activity — is the dominant driver of its nitrogen release.
When comparing two fertilizer products for cost efficiency, an applicator should calculate cost per pound of which nutrient to make a valid comparison?
Answer: Cost per pound of actual nutrient (e.g., N, P2O5, K2O)
Calculating cost per pound of actual nutrient (e.g., nitrogen) normalizes price across different grades and bag sizes for a true comparison.
A label states 'pH of a 1% solution: 6.8.' Why might an applicator reference this value?
Answer: To determine if the product can be tank-mixed with pH-sensitive pesticides
Solution pH affects compatibility with pesticides in tank mixes; some herbicides or fungicides degrade rapidly outside a narrow pH range.
A fertilizer label includes a 'salt index' or notes 'low salt index.' What does a lower salt index indicate for crop safety?
Answer: Lower osmotic stress on soil water, reducing seedling burn risk
A lower salt index means the product raises soil osmotic pressure less than a high-salt-index material, reducing the risk of germination inhibition and root burn.
A label for a liquid fertilizer reads '8-0-0-6S suspension.' What does the 'S' following the sulfur percentage indicate?
Answer: The sulfur element is listed rather than as SO3 or SO4
When 'S' follows the percentage, it denotes elemental sulfur content; if the form were sulfate, the label would typically state SO3 or SO4 equivalents.
Under AAPFCO Official Publication guidelines, which of the following micronutrients requires a statement of both total and water-soluble content on the label?
Answer: Manganese (Mn)
AAPFCO requires manganese to be declared as both total and water-soluble because manganese availability is highly influenced by soil pH and the distinction matters to applicators.
A commercial fertilizer label is found to have a guaranteed nitrogen content of 12%, but testing reveals only 10%. What is the most likely regulatory consequence for the manufacturer?
Answer: A deficiency penalty calculated on the dollar value of the nutrient shortage
Most state fertilizer laws impose a monetary deficiency penalty based on the value of the nutrient shortfall compared to what was guaranteed, payable to the purchaser or state fund.