Soil Science & Analysis Flashcards
7 cards from real GAP 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 Science & Analysis flashcards as text
A grower discovers that water infiltrates less than 0.5 inches per hour on their field. The most likely cause is:
Answer: A hardpan or compacted layer restricting downward water movement
Slow infiltration rates typically indicate a compacted layer or hardpan (like a traffic pan) that physically blocks water and root movement through the profile.
Which of the following is the correct sequence for the nitrogen cycle in agricultural soil?
Answer: Mineralization → Nitrification → Plant Uptake → Denitrification
Organic nitrogen is mineralized to ammonium, then nitrified to nitrate for plant uptake, and excess nitrate can be lost through denitrification under anaerobic conditions.
A GAP auditor asks about a farm's soil erosion prevention measures. Which response demonstrates best practices?
Answer: Using cover crops, buffer strips, and contour farming to reduce runoff
Cover crops, vegetated buffer strips, and contour farming are proven GAP practices that reduce erosion, protect water quality, and maintain soil structure.
What is the significance of the C:N ratio in soil organic matter decomposition?
Answer: It controls the rate of decomposition and nitrogen availability to crops
A high C:N ratio (e.g., straw >60:1) means decomposers tie up available nitrogen, while a low C:N ratio (e.g., legumes ~15:1) releases nitrogen as organic matter breaks down.
Which micronutrient deficiency in soil is most commonly associated with alkaline pH (above 7.5) and presents as yellowing between leaf veins (interveinal chlorosis)?
Answer: Iron
Iron becomes increasingly insoluble above pH 7.5, causing iron-deficiency chlorosis where young leaves yellow between veins while veins stay green.
Under GAP, when manure is applied as a soil amendment, which soil testing parameter becomes most critical to monitor over time?
Answer: Phosphorus accumulation and potential runoff risk
Repeated manure applications can lead to phosphorus saturation in soil, increasing the risk of phosphorus runoff into waterways and causing eutrophication.
What is the primary function of soil aggregates (peds) in agricultural soil?
Answer: They create a porous structure that supports aeration, drainage, and root growth
Well-formed aggregates create macropores for air and water movement and micropores for water retention, providing the ideal physical environment for root growth and soil biology.