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
A soil sample has a bulk density of 1.6 g/cm³. Which condition does this most likely indicate?
Answer: Highly compacted soil with restricted root growth
Bulk densities above 1.4–1.6 g/cm³ typically indicate compaction that restricts root penetration and water infiltration.
Which soil textural class holds the most plant-available water while still draining adequately?
Answer: Loam
Loam soils balance macropores for drainage and micropores for water retention, making them ideal for plant-available water.
When interpreting a soil test report, a base saturation of potassium (K) at 5% is considered:
Answer: Adequate for most crops
A K base saturation of 3–5% of CEC is generally considered adequate for most crops.
Which extraction method is most commonly used to assess plant-available phosphorus in neutral to alkaline soils in the western US?
Answer: Olsen (sodium bicarbonate)
The Olsen method using sodium bicarbonate is preferred for calcareous (alkaline) soils because it doesn't dissolve calcium phosphates.
Soil organic matter is most accurately measured in a laboratory by:
Answer: Loss-on-ignition (LOI) or Walkley-Black wet oxidation
Loss-on-ignition and Walkley-Black wet oxidation are standard laboratory methods to quantify soil organic matter content.
A soil pH of 5.2 would most likely cause deficiency of which nutrient in corn production?
Answer: Phosphorus (P)
Phosphorus availability sharply declines below pH 6.0 as it becomes fixed with aluminum and iron compounds.
What does a low soil electrical conductivity (EC) reading indicate in a field used for vegetable production?
Answer: Low soluble salt concentration, possible nutrient deficiency risk
Very low EC suggests few dissolved salts, which may indicate nutrient-poor soils requiring fertilizer inputs.