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