Soil Properties and Testing 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 Soil Properties and Testing flashcards as text
Which method is most appropriate for assessing soil test potassium (K) in high-CEC, fine-textured Midwestern soils?
Answer: Ammonium acetate extraction
Ammonium acetate extraction is the standard method for measuring exchangeable K in most US soil testing programs.
Soil organic matter contributes to fertility primarily because it:
Answer: Supplies and holds nutrients, improves water retention, and feeds soil biology
Organic matter functions as a nutrient reservoir, increases CEC, improves water-holding capacity, and sustains microbial communities.
A certified fertilizer applicator observes that soil test reports in the same field show high variability in P and K levels. The most appropriate response is:
Answer: Implement variable-rate application (VRA) based on grid or zone sampling
Variable-rate application uses spatially referenced soil data to apply the right rate in each zone, improving efficiency and reducing over-application.
The 'soil water potential' concept is important for fertilizer applicators because it determines:
Answer: Whether nutrients in solution can move to plant roots
Water potential gradients drive the movement of dissolved nutrients through soil to root surfaces via mass flow and diffusion.
Which of the following soil amendments would most effectively reclaim a sodic soil?
Answer: Gypsum (CaSO₄)
Gypsum supplies calcium to displace sodium from exchange sites without raising pH, and the sulfate leaches sodium out of the root zone.
Which soil test interpretation concept compares nutrient levels to crop yield response data from field experiments?
Answer: Sufficiency level approach (Critical Level)
The sufficiency level approach defines soil test values below which crop yield responses to added nutrients are likely, based on calibration research.
When a soil test lab reports 'ppm' (parts per million) for a nutrient, this is equivalent to:
Answer: Milligrams per kilogram (mg/kg) of soil
In soil testing, ppm on a dry-weight basis equals mg of nutrient per kg of soil (mg/kg).