Soil Quiz
Questions: 16 · 10 minutes
1. What is one important reason to grow a cover crop between main crops?
It can protect the surface, reduce erosion, and add organic inputs
It immediately changes the soil's mineral texture class
It eliminates the need for future soil testing
It prevents all competition for water and nutrients
2. Plants are struggling in an irrigated area where a pale crust has formed on the soil surface. Which laboratory measurement would most directly help investigate a buildup of soluble salts?
Particle-size distribution
Electrical conductivity
Bulk density
Aggregate stability
3. A soil test shows phosphorus is already above the recommended range for a garden. What is the most appropriate fertilizer response?
Apply a balanced fertilizer because every crop needs equal nutrient amounts
Add extra phosphorus to prevent it from becoming unavailable
Choose low- or no-phosphorus inputs and base other additions on identified needs
Lower the soil pH sharply so plants absorb more phosphorus
4. Two containers hold the same plant: one has sandy soil and the other has clay-rich soil. Under similar warm conditions, which watering approach is generally more suitable for the sandy soil?
Rare, very large applications because sand stores water for long periods
Smaller, more frequent applications because water drains readily
No watering until the soil forms a hard surface crust
The same fixed schedule, because texture does not affect water storage
5. A gardener finds many earthworms in a moist bed containing decomposing plant material. What is the most reasonable conclusion?
Conditions are supporting earthworm activity and organic-resource breakdown
The soil cannot have any drainage limitations
The soil is guaranteed to be free of contaminants
The soil must contain ideal levels of every plant nutrient
6. A garden bed is not compacted, yet water drains through it very slowly and the soil feels sticky when wet. Which feature is the most likely explanation?
A high proportion of clay-sized particles
A surface layer rich in undecomposed leaves
A high proportion of coarse sand
A low concentration of soluble salts
7. A soil pit shows gray colors with rusty mottles below the surface. What condition do these features most commonly suggest?
Persistent depletion of all organic matter
Periods of saturation and restricted oxygen availability
Recent contamination by synthetic fertilizer
Extremely rapid drainage through coarse sand
8. Rain runs off a bare sloping plot before much water enters the soil. Which change would most directly slow surface flow and protect against erosion?
Maintain mulch or dense ground cover across the slope
Remove plant residues so the surface dries faster
Break all aggregates into a smooth, fine seedbed
Apply a soluble fertilizer immediately before rain
9. Repeated foot traffic over a wet garden bed has left the soil dense and difficult to dig. Which practice best addresses the problem while reducing its return?
Work the bed with a rotary tiller whenever it is saturated
Apply extra phosphorus fertilizer before every planting
Loosen it when suitably moist, add organic matter, and keep traffic to paths
Cover the surface with a layer of fine clay
10. Why can clay and humus help soil retain positively charged nutrients such as potassium and calcium?
They make the nutrients permanently insoluble
They turn the nutrients into organic matter
Their large pores prevent nutrients from contacting water
Their charged surfaces provide cation-exchange sites
11. A soil test reports a pH of 5.2, and the intended crop grows best near neutral pH. Which amendment is commonly used, at a soil-test-recommended rate, to raise the pH?
Elemental sulfur
Ammonium sulfate
Sphagnum peat
Agricultural lime
12. What does soil texture describe?
The resistance of soil to changes in pH
The way soil particles form aggregates or clumps
The amount of decomposed organic material in soil
The relative proportions of sand, silt, and clay
13. Which term describes a loose, crumb-like arrangement of small soil aggregates that is common in biologically active topsoil?
Platy structure
Granular structure
Massive structure
Single-grain structure
14. Which is a typical benefit of adding well-decomposed organic matter to soil?
It converts all clay particles into silt particles
It permanently fixes the soil at a neutral pH
It can support aggregation, nutrient retention, and water management
It removes the need to monitor plant nutrients
15. A plant's older leaves turn uniformly pale green and then yellow, while newer growth remains greener at first. Which nutrient shortage most closely matches this pattern?
Iron deficiency, which typically begins between veins of young leaves
Phosphorus deficiency, which often causes dark or purplish foliage
Nitrogen deficiency, because nitrogen can move from older to newer leaves
Calcium deficiency, which primarily affects new growing points
16. In a jar test, a shaken soil-and-water mixture is left undisturbed. Which particles generally settle first?
Clay particles, because they carry electrical charges
Organic particles, because they bind to water
Silt particles, because they contain the most minerals
Sand particles, because they are the largest and heaviest