Soil Science MCQs January 8, 2026August 13, 2024 by u930973931_answers 40 min Score: 0 Attempted: 0/40 Subscribe 1. What is soil? (A) A natural resource composed of minerals, organic matter, water, and air (B) A type of rock (C) A liquid substance (D) A form of energy 2. Which soil horizon is known as the topsoil? (A) Horizon D (B) Horizon B (C) Horizon C (D) Horizon A 3. What is ‘soil pH’? (A) The amount of organic matter in the soil (B) A measure of the acidity or alkalinity of the soil (C) The color of the soil (D) The soil’s texture 4. Which soil texture has the smallest particles? (A) Sand (B) Clay (C) Silt (D) Loam 5. What is ‘soil erosion’? (A) The removal of the top layer of soil by wind, water, or human activity (B) The addition of nutrients to the soil (C) The process of soil formation (D) The increase in soil fertility 6. Which of the following is a primary soil nutrient? (A) Iron (B) Calcium (C) Sodium (D) Nitrogen 7. What is ‘soil structure’? (A) The soil’s pH level (B) The amount of water in the soil (C) The color of the soil (D) The arrangement of soil particles into aggregates 8. Which process involves the breaking down of rocks into smaller particles? (A) Leaching (B) Erosion (C) Weathering (D) Compaction 9. What is ‘soil fertility’? (A) The ability of soil to provide essential nutrients for plant growth (B) The density of soil particles (C) The soil’s pH level (D) The amount of organic matter in the soil 10. Which soil property is measured by the texture triangle? (A) Soil texture (proportions of sand, silt, and clay) (B) Soil pH (C) Soil organic matter (D) Soil moisture 11. What is ‘soil salinization’? (A) The process of soil formation (B) The accumulation of soluble salts in the soil (C) The reduction of soil nutrients (D) The removal of soil particles by wind 12. Which soil horizon is known as the subsoil? (A) Horizon B (B) Horizon A (C) Horizon C (D) Horizon D 13. What does ‘soil permeability’ refer to? (A) The amount of nutrients in the soil (B) The ability of soil to transmit water and air (C) The soil’s color (D) The pH level of the soil 14. What is ‘soil compaction’? (A) The addition of organic matter to the soil (B) The process of increasing soil density by reducing pore spaces (C) The increase in soil texture (D) The reduction of soil acidity 15. Which soil type has the highest water-holding capacity? (A) Silt (B) Sand (C) Clay (D) Loam 16. What is ‘soil organic matter’? (A) The soil’s pH level (B) The mineral content of the soil (C) The soil’s texture (D) Decomposed plant and animal material in the soil 17. What is ‘leaching’ in soil science? (A) The removal of dissolved nutrients from the soil by water (B) The addition of nutrients to the soil (C) The process of soil formation (D) The compaction of soil particles 18. Which soil property affects plant root penetration and water movement? (A) Soil color (B) Soil texture (C) Soil organic matter (D) Soil pH 19. What is the primary purpose of soil testing? (A) To evaluate soil structure (B) To measure soil color (C) To determine soil nutrient levels and pH for effective management (D) To assess soil compaction 20. Which of the following is a factor that influences soil formation? (A) Parent material (B) Soil color (C) Soil texture (D) Soil density 21. What is ‘soil tilth’? (A) The pH level of the soil (B) The physical condition of soil as it relates to its suitability for plant growth (C) The amount of organic matter in the soil (D) The soil’s texture 22. Which of the following is an indicator of soil erosion? (A) Increased soil moisture (B) Increased soil organic matter (C) Rills and gullies (D) Reduced soil density 23. What is the role of ‘earthworms’ in soil health? (A) They reduce soil organic matter (B) They increase soil acidity (C) They compact the soil (D) They improve soil structure and increase nutrient availability 24. Which of the following is a method to prevent soil erosion? (A) Deep plowing (B) Increasing soil compaction (C) Removing vegetation (D) Planting cover crops 25. What is ‘soil moisture’? (A) The amount of water present in the soil (B) The soil’s pH level (C) The soil’s texture (D) The amount of organic matter in the soil 26. What does ‘soil texture’ refer to? (A) The size distribution of mineral particles in soil (sand, silt, clay) (B) The soil’s pH level (C) The amount of organic matter in the soil (D) The color of the soil 27. What is ‘soil infiltration’? (A) The removal of water from the soil (B) The process by which water enters and moves through the soil (C) The addition of organic matter to the soil (D) The increase in soil density 28. Which of the following is a soil amendment that improves soil structure? (A) Clay (B) Sand (C) Gravel (D) Compost 29. What is ‘soil texture triangle’ used for? (A) To measure soil pH (B) To classify soil based on its texture (sand, silt, clay) (C) To determine soil fertility (D) To assess soil moisture 30. What does ‘soil aeration’ refer to? (A) The increase in soil density (B) The addition of nutrients to the soil (C) The removal of soil particles (D) The exchange of gases between the soil and the atmosphere 31. Which soil horizon contains the most organic matter? (A) Horizon B (B) Horizon A (C) Horizon C (D) Horizon D 32. What is ‘soil bulk density’? (A) The weight of soil per unit area (B) The mass of soil per unit volume, including air space (C) The soil’s pH level (D) The amount of organic matter in the soil 33. Which of the following is a consequence of soil compaction? (A) Increased soil fertility (B) Reduced root growth and water infiltration (C) Enhanced soil structure (D) Increased soil aeration 34. What is ‘soil texture’ determined by? (A) The soil’s pH level (B) The proportion of sand, silt, and clay in the soil (C) The amount of organic matter in the soil (D) The soil’s color 35. What is ‘soil profile’? (A) A vertical section of soil that displays all its horizons (B) The surface layer of the soil (C) The topsoil layer only (D) The underground water table 36. Which process leads to the formation of ‘humus’? (A) Soil compaction (B) Soil erosion (C) Decomposition of organic matter (D) Soil leaching 37. What is ‘soil conservation’? (A) The addition of nutrients to the soil (B) The process of soil formation (C) The practice of preventing soil degradation and erosion (D) The removal of soil particles 38. Which soil type has the lowest water-holding capacity? (A) Silt (B) Clay (C) Sand (D) Loam 39. What is the main cause of soil degradation? (A) Natural weathering processes (B) Unsustainable land management practices (C) Increase in soil organic matter (D) Soil aeration 40. Which soil horizon is often referred to as ‘bedrock’? (A) Horizon C (B) Horizon A (C) Horizon B (D) Horizon D