Soil Organic Matter MCQs Quiz 1

1. The conceptual model of SOM describes it as _______

 Static pool

 Only humified substances

 Discrete chemical compounds only

 Dynamic continuum of organic materials

2. Soil Organic Matter is best defined as _______

 Only humus fraction

 A dynamic mixture of Humified and non-humified organic fractions

 A mixture of inorganic minerals only

 Only microbial biomass

3. Labile carbon in soil organic matter is best defined as _______

 Highly stabilized and protected within microaggregates

 Chemically complex and resistant to microbial degradation

 Insoluble and mineral-associated carbon fraction

 Easily decomposable and rapidly cycled by soil microorganisms

4. Which component contributes most to the recalcitrance (resistance to decomposition) of Soil Organic Matter? _______

 Simple sugars

 Lignin

 Organic acids

 Amino acids

5. Soil Organic Matter acts as a major _______ of carbon

 None of These

 Source

 Sink

 Both source and sink

6. Soil Organic Carbon (SOC) differs from Soil Organic Matter because SOC represents _______

 Only carbon fraction of organic matter

 Total organic matter including minerals

 Only labile organic pools

 Only microbial carbon

7. The Soil Organic Matter (SOM) pool with the fastest turnover rate is _______

 Stable pool

 Passive pool

 Humus pool

 Active pool

8. Recalcitrant carbon in soil is best characterized as _______

 Resistant to microbial breakdown and slow turnover carbon

 Easily soluble organic fraction available to microbes

 Highly labile and nutrient-rich organic material

 Rapidly decomposed and short-lived carbon pool

9. Soil Organic Matter (SOM) primarily contains which of the following elements, except _______

 Hydrogen

 Silicon

 Carbon

 Oxygen

10. The Van Bemmelen factor used to convert Soil Organic Carbon (SOC) to Soil Organic Matter (SOM) is _______

 1.27

 1.24

 1.72

 2.57

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Question 1 of 10

Soil Science MCQs