1. Which of the following is a primary function of soil?
a) Providing habitat for microorganisms
b) Absorbing carbon dioxide
c) Storing energy
d) Filtering water
Answer: a) Providing habitat for microorganisms
2. The pH of soil affects the availability of which of the following nutrients?
a) Iron
b) Calcium
c) Nitrogen
d) All of the above
Answer: d) All of the above
3. The process of nitrogen fixation in soil is primarily carried out by:
a) Bacteria
b) Fungi
c) Protozoa
d) Earthworms
Answer: a) Bacteria
4. Which of the following is the most common soil texture?
a) Clay
b) Loam
c) Silt
d) Sand
Answer: b) Loam
5. The term “Cation Exchange Capacity (CEC)” refers to the soil’s ability to hold and exchange which type of ions?
a) Anions
b) Cations
c) Both anions and cations
d) None of the above
Answer: b) Cations
6. Which of the following is considered a micronutrient for plants?
a) Nitrogen
b) Potassium
c) Manganese
d) Phosphorus
Answer: c) Manganese
7. The ideal pH range for most crops is between:
a) 4.0 to 5.0
b) 5.5 to 6.5
c) 6.0 to 7.0
d) 7.5 to 8.5
Answer: b) 5.5 to 6.5
8. Which of the following soil orders is most commonly found in tropical regions?
a) Mollisols
b) Oxisols
c) Spodosols
d) Aridisols
Answer: b) Oxisols
9. Soil erosion can be reduced by which of the following techniques?
a) Crop rotation
b) Contour farming
c) Windbreaks
d) All of the above
Answer: d) All of the above
10. Which type of soil is most prone to erosion due to high sand content?
a) Loamy soil
b) Clay soil
c) Sandy soil
d) Silt soil
Answer: c) Sandy soil
11. Soil structure can be improved by adding:
a) Organic matter
b) Chemical fertilizers
c) Pesticides
d) Herbicides
Answer: a) Organic matter
12. Which of the following is the primary cause of soil salinization?
a) Over-irrigation
b) Excessive fertilization
c) Erosion
d) Deforestation
Answer: a) Over-irrigation
13. Which process in soil leads to the conversion of organic matter into humus?
a) Mineralization
b) Decomposition
c) Nitrification
d) Denitrification
Answer: b) Decomposition
14. The soil horizon that contains a mixture of organic material and mineral particles is called:
a) O horizon
b) A horizon
c) B horizon
d) C horizon
Answer: b) A horizon
15. Soil compaction negatively impacts plant growth by:
a) Increasing root aeration
b) Reducing water infiltration
c) Improving nutrient retention
d) Enhancing root penetration
Answer: b) Reducing water infiltration
16. Which of the following is an essential soil nutrient required for photosynthesis?
a) Nitrogen
b) Phosphorus
c) Magnesium
d) Potassium
Answer: c) Magnesium
17. The Soil Taxonomy system divides soils into how many primary categories?
a) 4
b) 6
c) 12
d) 26
Answer: c) 12
18. The principle of “crop rotation” is mainly used to improve:
a) Soil fertility
b) Soil texture
c) Soil temperature
d) Soil pH
Answer: a) Soil fertility
19. Which of the following is used to measure the soil’s ability to retain water?
a) Bulk density
b) Porosity
c) Permeability
d) Field capacity
Answer: d) Field capacity
20. Which of the following is NOT a characteristic of clay soils?
a) Fine particles
b) High water retention
c) Good drainage
d) High nutrient retention
Answer: c) Good drainage
21. Which soil component is primarily responsible for water retention?
a) Organic matter
b) Clay
c) Sand
d) Gravel
Answer: b) Clay
22. The process of mineralization in soil involves the conversion of:
a) Organic matter to inorganic form
b) Inorganic matter to organic form
c) Water into gas
d) Nutrients into water
Answer: a) Organic matter to inorganic form
23. Which of the following is an important factor influencing the rate of soil erosion?
a) Vegetative cover
b) Soil texture
c) Slope gradient
d) All of the above
Answer: d) All of the above
24. The ideal soil texture for agriculture is:
a) Sandy
b) Loam
c) Clay
d) Silt
Answer: b) Loam
25. Which of the following is the main source of nitrogen for plants in the soil?
a) Water
b) Air
c) Organic matter
d) Soil minerals
Answer: c) Organic matter
26. Which of the following is the main cause of soil acidification?
a) Acid rain
b) Organic decomposition
c) Fertilizer application
d) All of the above
Answer: d) All of the above
27. The B horizon of soil is primarily composed of:
a) Organic material
b) Weathered rock and minerals
c) Clay and sand
d) Nutrient-rich organic matter
Answer: b) Weathered rock and minerals
28. Which of the following is a measure of soil’s ability to supply plant nutrients?
a) Soil texture
b) Soil organic carbon
c) Cation exchange capacity (CEC)
d) Bulk density
Answer: c) Cation exchange capacity (CEC)
29. Which of the following processes is responsible for the release of nitrogen into the atmosphere?
a) Nitrification
b) Denitrification
c) Ammonification
d) Fixation
Answer: b) Denitrification
30. In soil science, which term refers to the relationship between water and soil particles?
a) Soil structure
b) Soil texture
c) Soil moisture
d) Soil consistency
Answer: c) Soil moisture
31. Which soil nutrient is essential for root development?
a) Nitrogen
b) Phosphorus
c) Potassium
d) Calcium
Answer: b) Phosphorus
32. The process of leaching involves the movement of nutrients from:
a) Topsoil to groundwater
b) Subsoil to surface soil
c) Soil to plant roots
d) Organic matter to soil
Answer: a) Topsoil to groundwater
33. Which soil component contributes most to soil’s water holding capacity?
a) Sand
b) Silt
c) Clay
d) Organic matter
Answer: c) Clay
34. Which of the following factors influence the soil’s permeability?
a) Soil texture
b) Organic matter content
c) Soil structure
d) All of the above
Answer: d) All of the above
35. Which of the following is a common soil amendment used to increase soil acidity?
a) Lime
b) Gypsum
c) Sulfur
d) Sand
Answer: c) Sulfur
36. Which process in soil is associated with the breakdown of plant and animal matter?
a) Nitrogen fixation
b) Decomposition
c) Mineralization
d) Evaporation
Answer: b) Decomposition
37. Which of the following is the process of converting organic nitrogen to ammonia in the soil?
a) Denitrification
b) Nitrification
c) Ammonification
d) Nitrogen fixation
Answer: c) Ammonification
38. The process by which plants absorb nitrogen from the soil is called:
a) Nitrogen fixation
b) Nitrification
c) Assimilation
d) Ammonification
Answer: c) Assimilation
39. Which of the following is a characteristic of soil that affects the movement of water through it?
a) Bulk density
b) Permeability
c) Organic matter content
d) All of the above
Answer: b) Permeability
40. The Soil Profile consists of:
a) One horizon
b) Two horizons
c) Three horizons
d) Several horizons
Answer: d) Several horizons
41. Which soil horizon is composed mainly of parent material?
a) O horizon
b) A horizon
c) B horizon
d) C horizon
Answer: d) C horizon
42. Which of the following types of soil erosion is caused by wind?
a) Sheet erosion
b) Water erosion
c) Wind erosion
d) Gully erosion
Answer: c) Wind erosion
43. Which of the following factors influences the rate of soil erosion?
a) Vegetative cover
b) Soil texture
c) Slope of land
d) All of the above
Answer: d) All of the above
44. Which of the following is a primary cause of soil degradation?
a) Overuse of fertilizers
b) Deforestation
c) Overgrazing
d) All of the above
Answer: d) All of the above
45. In soil science, “soil aggregation” refers to the:
a) Size of the soil particles
b) Clustering of soil particles into larger units
c) Amount of water in the soil
d) Ability of soil to retain nutrients
Answer: b) Clustering of soil particles into larger units
46. Which of the following is the primary source of soil fertility?
a) Organic matter
b) Water
c) Soil minerals
d) Air
Answer: a) Organic matter
47. Which element is a vital micronutrient for chlorophyll production in plants?
a) Iron
b) Magnesium
c) Phosphorus
d) Potassium
Answer: a) Iron
48. Which soil property is defined as the weight of soil per unit volume?
a) Bulk density
b) Porosity
c) Soil texture
d) Moisture content
Answer: a) Bulk density
49. Which of the following types of soil contains the highest proportion of humus?
a) Clay soil
b) Sandy soil
c) Loamy soil
d) Silt soil
Answer: c) Loamy soil
50. Which of the following is the most efficient method of improving soil structure?
a) Adding sand
b) Applying organic matter
c) Using chemical fertilizers
d) Increasing irrigation
Answer: b) Applying organic matter
51. The maximum amount of water that soil can hold is called:
a) Saturation capacity
b) Field capacity
c) Wilting point
d) Hygroscopic water
Answer: a) Saturation capacity
52. Which of the following factors can lead to soil compaction?
a) Overgrazing
b) Excessive tillage
c) Heavy machinery
d) All of the above
Answer: d) All of the above
53. The process of leaching in soil refers to:
a) The removal of soluble nutrients from the soil
b) The addition of nutrients to the soil
c) The breakdown of organic matter
d) The absorption of water by roots
Answer: a) The removal of soluble nutrients from the soil
54. Which of the following is NOT a soil conservation method?
a) Contour farming
b) Strip cropping
c) Clear-cutting forests
d) Terracing
Answer: c) Clear-cutting forests
55. The application of lime to acidic soils is primarily used to:
a) Increase nitrogen availability
b) Increase soil pH
c) Improve soil texture
d) Improve soil structure
Answer: b) Increase soil pH
56. Which of the following is a practice to control soil salinity?
a) Mulching
b) Proper drainage
c) Increasing tillage
d) Over-irrigation
Answer: b) Proper drainage
57. Which of the following is a typical symptom of nutrient deficiency in plants?
a) Yellowing of leaves (chlorosis)
b) Excessive growth
c) Leaf curl
d) Strong fragrance
Answer: a) Yellowing of leaves (chlorosis)
58. The physical weathering of soil results in the breakdown of:
a) Organic matter
b) Soil particles into smaller sizes
c) Soil nutrients
d) Soil microorganisms
Answer: b) Soil particles into smaller sizes
59. Which of the following crops requires the highest amount of potassium from the soil?
a) Wheat
b) Rice
c) Corn
d) Potatoes
Answer: c) Corn
60. The soil erosion control technique that involves planting grasses and trees along the contour lines is known as:
a) Terracing
b) Windbreaks
c) Strip cropping
d) Contour planting
Answer: d) Contour planting
61. Which of the following processes leads to the transformation of ammonia into nitrites and nitrates in soil?
a) Nitrification
b) Denitrification
c) Nitrogen fixation
d) Ammonification
Answer: a) Nitrification
62. Which of the following is a primary cause of soil compaction in agricultural fields?
a) Use of organic fertilizers
b) Use of heavy farm equipment
c) Crop rotation
d) Planting cover crops
Answer: b) Use of heavy farm equipment
63. Which of the following is a method of improving soil fertility?
a) Increasing irrigation frequency
b) Adding chemical fertilizers only
c) Adding organic matter and crop residues
d) Reducing soil aeration
Answer: c) Adding organic matter and crop residues
64. Which soil microorganism is most responsible for decomposing organic material in soil?
a) Fungi
b) Protozoa
c) Bacteria
d) Algae
Answer: a) Fungi
65. Which of the following is an effect of excessive irrigation on soil?
a) Increased nutrient availability
b) Soil salinization
c) Improved soil structure
d) Decreased soil erosion
Answer: b) Soil salinization
66. The percentage of soil pores filled with air or water is called:
a) Bulk density
b) Porosity
c) Permeability
d) Saturation
Answer: b) Porosity
67. Which of the following is used to determine the nutrient-holding capacity of soil?
a) Bulk density
b) Cation exchange capacity (CEC)
c) Soil pH
d) Soil texture
Answer: b) Cation exchange capacity (CEC)
68. Which of the following is a characteristic of clay soils?
a) Poor drainage
b) Good aeration
c) High permeability
d) Low nutrient-holding capacity
Answer: a) Poor drainage
69. The process by which nitrogen gas is converted into a form usable by plants is called:
a) Nitrogen fixation
b) Nitrification
c) Denitrification
d) Ammonification
Answer: a) Nitrogen fixation
70. Which of the following soil amendments is used to improve soil drainage in clayey soils?
a) Lime
b) Gypsum
c) Organic matter
d) Sand
Answer: d) Sand
71. Which soil type is most prone to nutrient leaching?
a) Sandy soil
b) Clay soil
c) Loamy soil
d) Silt soil
Answer: a) Sandy soil
72. Which type of irrigation method is most effective for conserving water in sandy soils?
a) Furrow irrigation
b) Drip irrigation
c) Flood irrigation
d) Sprinkler irrigation
Answer: b) Drip irrigation
73. Which of the following is NOT a benefit of composting in soil management?
a) Increases organic matter
b) Improves soil structure
c) Reduces soil salinity
d) Increases microbial activity
Answer: c) Reduces soil salinity
74. The addition of which of the following substances to soil will decrease its acidity?
a) Gypsum
b) Lime
c) Sulfur
d) Phosphates
Answer: b) Lime
75. Which of the following is a major nutrient for plants obtained from the soil?
a) Oxygen
b) Nitrogen
c) Hydrogen
d) Carbon
Answer: b) Nitrogen
76. The process by which water is absorbed by plant roots and moves through the soil is called:
a) Evaporation
b) Transpiration
c) Percolation
d) Osmosis
Answer: c) Percolation
77. Which of the following is NOT a method to prevent soil erosion?
a) Crop rotation
b) Planting grass or trees on slopes
c) Over-irrigation
d) Terracing
Answer: c) Over-irrigation
78. Which soil property is most affected by the amount of organic matter in the soil?
a) Soil texture
b) Soil permeability
c) Soil color
d) Soil fertility
Answer: d) Soil fertility
79. Which of the following elements is considered a secondary macronutrient for plants?
a) Nitrogen
b) Phosphorus
c) Calcium
d) Iron
Answer: c) Calcium
80. Which of the following is an important practice in sustainable soil management?
a) Excessive tilling
b) Continuous monocropping
c) Maintaining soil cover with cover crops
d) Overuse of chemical fertilizers
Answer: c) Maintaining soil cover with cover crops
