Soil Organic Matter MCQs Quiz 5

1. Turnover of the passive soil organic carbon (SOC) pool typically occurs over _______

 Months

 Decades to centuries

 Years

 Days

2. _______ mineral fraction stabilizes soil organic matter (SOM) most effectively through chemical binding and physical protection

 Clay

 Gravel

 Sand

 Quartz

3. Which agricultural practice is most effective at increasing soil organic matter (SOM) over time?

 Intensive conventional plowing

 Overgrazing of pastures

 Burning crop residues

 Cover cropping

4. Which of the following conditions most accelerates soil organic matter (SOM) decomposition?

 Frozen soil (permafrost)

 Low temperature

 Dry soil

 Warm and moist conditions

5. A positive priming effect in soil results in _______

 Reduced microbial activity

 Increased decomposition of native soil organic matter (SOM)

 No change in soil carbon dynamics

 Enhanced carbon sequestration without affecting decomposition

6. Mineralization in soil nutrient cycling is _______

 Conversion of organic forms to inorganic forms

 Conversion of inorganic forms to organic forms

 Formation of stable humus

 Fixation of atmospheric carbon

7. In current soil science models, soil organic matter (SOM) formation is primarily driven by _______

 Leaching of dissolved organic carbon to deeper horizons

 Direct plant residue humification

 Mineral weathering processes

 Microbial processing of plant inputs

8. In soil science, humification refers to _______

 Release of inorganic nutrients (e.g., NH₄⁺, NO₃⁻) from organic matter

 Formation of humic substances

 Complete decomposition of organic matter to CO₂

 Downward movement of dissolved organic matter through the soil profile

9. _______ reduces soil organic matter (SOM) stabilization

 Sandy soil texture

 Soil aggregation

 High clay content

 Mineral binding

10. In soil biogeochemistry, the “microbial carbon pump” refers to the process by which microorganisms _______

 Completely mineralize organic carbon to CO₂

 Fix atmospheric CO₂ via autotrophy

 Leach dissolved organic carbon (DOC) to deeper soil layers

 Convert labile plant-derived carbon into stable soil organic matter (SOM) through microbial necromass and metabolites

 Loading …

Question 1 of 10

Soil Organic Matter MCQs [Explore all MCQs]

[Soil Science MCQs] [Plant Nutrition MCQs] [Crop and Environment MCQs]
[Soil Physical Properties MCQs] [Soil Chemical Properties MCQs]
[General Agriculture MCQs] [Agronomy MCQs] [Plant Physiology MCQs]
[Biology MCQs] [Botany MCQs ] [Zoology MCQs] [Enzymology MCQs]
[Cell Structure & Cell Organelles MCQs] [Gene Expression MCQs]

Soil Science MCQs