Soil Organic Matter MCQs Quiz 9

1. Conversion of inorganic nutrients into microbial biomass is called ______________

 Nitrification

 Immobilization

 Mineralization

 Denitrification

2. Soil carbon loss is most accelerated under ________________

 High clay content

 Cool climate

 Addition of organic matter

 Increased soil disturbance and oxygen exposure

3. Which process leads to the formation of chemically complex, recalcitrant organic compounds that resist microbial breakdown?

 Leaching

 Immobilization

 Mineralization

 Humification

4. Which organic amendment is most effective in long-term improvement of cation exchange capacity of a sandy soil?

 Well-decomposed vermicompost

 Fresh FYM

 Raw poultry manure

 Fresh green biomass

5. Nitrogen mineralization is best defined as the microbial conversion of organic nitrogen into _______

 Gaseous nitrogen exclusively

 Ammonia

 Stable organic forms

 NH₄⁺, NO₃⁻

6. Under aerobic conditions, main gas released during decomposition is _________

 Carbon dioxide

 Nitrogen

 Hydrogen

 Oxygen

7. Vermicompost enhances soil aggregation primarily through ______________

 Production of polysaccharides and other microbial binding agents

 Reducing overall soil microbial activity

 Increasing the sand fraction in soil

 Increasing soil acidity to bind particles chemically

8. Which composting method involves turning the pile regularly to maintain aerobic conditions and achieve rapid decomposition?

 Vermicomposting

 Anaerobic digestion

 Pit composting

 Aerobic windrow composting

9. In soil, ___________________ regulates  decomposition rate

 C:N ratio

 Soil moisture ratio

 pH ratio

 CEC ratio

10. Which soil component most significantly influences nutrient availability, structure, and biological activity?

 Sand fraction

 Silt fraction

 Soil organic matter

 Soil water

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