Soil Organic Matter MCQs Quiz 7 Posted on May 3, 2026Author agropublishers 0 1. In soil, humus is formed by the process of ___________ Decomposition Leaching Weathering Evaporation 2. Formation of stable humus is primarily associated with the decomposition of _________________ Simple carbohydrates Nitrogen-rich compounds Lignin-rich materials 3. During nitrogen mineralization, organic nitrogen is converted into __________ Gaseous nitrogen only Plant-available inorganic forms Organic compounds Humus 4. Fungi are primarily responsible for the decomposition of _______________ Sugars Lignin Proteins Starch 5. A key limitation of applying raw poultry manure directly to vegetable crops is ____________ Very low nitrogen content Excessive lignin leading to slow decomposition Alkaline pH damaging roots Risk of ammonia toxicity and pathogen contamination 6. Proteins in soil organic matter are primarily a rich source of _______ Sulfur Phosphorous Potassium Nitrogen 7. Conversion of organic nitrogen into plant-available form is called __________ Mineralization Leaching Immobilization Humification 8. _____________ are considered as Primary decomposers in soil Protozoa Algae Viruses Bacteria 9. A key limitation of applying fresh farmyard manure (FYM) to soil is ___________ Rapid humification leading to nutrient loss Very low microbial activity in the manure Excessively high nutrient concentration causing toxicity High risk of nitrogen immobilization due to a wide C:N ratio 10. The C:N ratio (Carbon-to-Nitrogen ratio) in soil mainly controls _________________ Water flow Soil color Soil depth Nutrient cycling Loading … Question 1 of 10
