Soil Organic Matter MCQs Quiz 11

1. Humus formation in soil results primarily from ______________

 Downward movement of nutrients

 Physical breakdown of rocks

 Water loss from soil

 Microbial decomposition of organic matter

2. Conversion of labile organic matter into stable humus is known as__________________

 Decomposition

 Immobilization

 Humification

 Mineralization

3. ____________ is a group of symbiotic nitrogen-fixing bacteria associated with leguminous crops

 Bacillus thuringiensis

 Rhizobium

 Azotobacter

 Pseudomonas

4. Compared with farnyard manure, vermicompost generally contains ___________

 Higher C:N ratio

 Lower nutrient availability

 More plant-available nutrients

 Higher lignin content

5. Under anaerobic decomposition ____________ gas produced

 Methane

 Nitrogen

 Oxygen

 Carbon dioxide

6. The carbon to nitrogen (C:N) ratio in soil organic matter primarily influences ___________

 Soil structure

 Rate of decomposition and nutrient availability

 Water retention

 Soil texture

7. A major advantage of vermicomposting over traditional aerobic composting is ____________

 No need for moisture control

 Production of nutrient-rich, finely textured castings

 Higher temperature for pathogen kill

 Faster breakdown of lignin

8. Soil dehydrogenase activity is commonly used as an indicator of _______________

 Overall soil microbial metabolic activity

 Lignin decomposition rate

 Specific nitrogen-fixing potential

 Phosphorus availability

9. ___________ is the capture and long-term storage of carbon in soil organic matter

 Carbon volatilization

 Carbon leaching

 Carbon mineralization

 Carbon sequestration

10. Cellulase activity in soil primarily contributes to ____________

 Breakdown of cellulose into simple sugars

 Lignin oxidation

 Protein hydrolysis

 Phosphorus release

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