Soil Organic Matter MCQs Quiz 5

1. _______ reduces soil organic matter (SOM) stabilization

 High clay content

 Mineral binding

 Soil aggregation

 Sandy soil texture

2. Mineralization in soil nutrient cycling is _______

 Conversion of inorganic forms to organic forms

 Fixation of atmospheric carbon

 Conversion of organic forms to inorganic forms

 Formation of stable humus

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

 Gravel

 Quartz

 Clay

 Sand

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

 Dry soil

 Warm and moist conditions

 Low temperature

 Frozen soil (permafrost)

5. A positive priming effect in soil results in _______

 Increased decomposition of native soil organic matter (SOM)

 Reduced microbial activity

 No change in soil carbon dynamics

 Enhanced carbon sequestration without affecting decomposition

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

 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

 Completely mineralize organic carbon to CO₂

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

 Intensive conventional plowing

 Burning crop residues

 Cover cropping

 Overgrazing of pastures

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

 Years

 Decades to centuries

 Months

 Days

9. In soil science, humification refers to _______

 Complete decomposition of organic matter to CO₂

 Downward movement of dissolved organic matter through the soil profile

 Formation of humic substances

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

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

 Mineral weathering processes

 Microbial processing of plant inputs

 Direct plant residue humification

 Leaching of dissolved organic carbon to deeper horizons

 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