Soil Management Flashcards
7 cards from real CCA 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 Management flashcards as text
Which type of soil water is held so tightly by soil particles that it is unavailable to plants?
Answer: Hygroscopic water
Hygroscopic water is bound tightly to soil particles at matric potentials below −3,100 kPa and cannot be extracted by plant roots.
Which carbon-to-nitrogen (C:N) ratio range promotes net nitrogen mineralization rather than immobilization by soil microbes?
Answer: C:N < 20:1
When the C:N ratio of residue falls below about 20:1, microbes have excess nitrogen relative to carbon needs, releasing mineral N through net mineralization.
Which soil test measurement is most closely related to a soil's ability to hold and supply cations such as Ca²⁺, Mg²⁺, and K⁺ to plants?
Answer: Cation exchange capacity (CEC)
Cation exchange capacity (CEC) measures the total quantity of cations a soil can hold on exchange sites, directly reflecting nutrient-holding ability.
In a soil with a high sodium adsorption ratio (SAR), which physical problem is most likely to develop?
Answer: Soil dispersion and loss of structure
High SAR soils have sodium dominating exchange sites, which causes clay dispersion, aggregate breakdown, and dramatic reduction in hydraulic conductivity.
Which micronutrient deficiency is most commonly associated with high-pH calcareous soils and appears as interveinal chlorosis on young leaves?
Answer: Iron
Iron deficiency chlorosis is common in calcareous soils (pH > 7.5) because Fe³⁺ precipitates as insoluble hydroxides, and young leaves show interveinal yellowing first.
Which soil water potential term describes the component due to dissolved salts reducing water availability to plant roots?
Answer: Osmotic (solute) potential
Osmotic potential (also called solute potential) is the component of total water potential that decreases water availability due to dissolved salts in the soil solution.
What is the primary reason no-till systems tend to stratify nutrients near the soil surface?
Answer: Surface-applied nutrients are not incorporated by tillage
Without tillage to incorporate broadcast fertilizers and lime, nutrients accumulate at or near the soil surface rather than being mixed throughout the tillage layer.