Free Soil Science MCQs with Answers
377 Soil Science MCQs from Agriculture, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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377 questions · page 6 of 19
- A. Acidic
- B. Alkaline
- C. Acidic & Alkaline
- D. Calcareous
Explanation: Soils near canal banks may become alkaline because canal seepage raises groundwater and evaporation concentrates salts and sodium near the…
Correct answer: Alkaline- A. Pedologist
- B. Soil chemist
- C. agronomistSoil
- D. Edaphologists
Explanation: Edaphologists study soil in relation to plant growth and production, whereas pedologists focus more broadly on soil formation…
Correct answer: Edaphologists- A. Leaching
- B. Percolation
- C. Infiltration
- D. Seeping
Explanation: Leaching is the downward removal of soluble nutrients, salts or contaminants by water moving through the soil.
Correct answer: Leaching- A. Field capacity to super available water
- B. Field capacity to wilting point
- C. Only field capacity
- D. All of the above
Explanation: Available water is the soil moisture held between field capacity and the permanent wilting point.
Correct answer: Field capacity to wilting point- A. Aluminum
- B. Silicon
- C. None of the above
- D. Sodium
Explanation: Oxygen is the most abundant element in Earth’s crust, but it is not listed among the choices.
Correct answer: None of the above- A. Humus
- B. Clay
- C. both A & B
- D. Only Clay
Explanation: Humus has a higher specific heat than clay, meaning it requires more heat to raise its temperature by the same amount.
Correct answer: Humus- A. None of the above
- B. Fungi
- C. Algae
- D. Actinomycetes
Explanation: Submerged soil becomes oxygen-deficient, so organic matter is decomposed mainly by anaerobic microorganisms, especially bacteria.
Correct answer: None of the above- A. Umbric epipedon
- B. Ochric epipedon
- C. Mollic epipedon
- D. Melanic epipedon
Explanation: The ochric epipedon is a surface horizon that fails to meet the requirements for darker, thicker or more organic epipedons such as mollic…
Correct answer: Ochric epipedon- A. 72 %
- B. 62 %
- C. 58%
- D. Al of the above
Explanation: Soil organic matter is conventionally estimated to contain about 58% organic carbon, with the remainder consisting mainly of hydrogen…
Correct answer: 58%- A. Tetrahedral sheet
- B. Triple octahedral sheet
- C. Octahedral sheet
- D. Both A & C
Explanation: A phyllosilicate layer combines one tetrahedral sheet with one octahedral sheet, forming a 1:1 or 2:1 clay-mineral structure depending on…
Correct answer: Both A & C- A. Negative
- B. Positive
- C. Zero
- D. All of the above
Explanation: Soil colloids are predominantly negatively charged because of isomorphous substitution and dissociation of surface groups.
Correct answer: Negative- A. Aridisols
- B. None of the above
- C. Mollisols
- D. Alfisols
Explanation: Aridisols, Alfisols and Mollisols are all recognized soil orders occurring in Pakistan, although Aridisols are especially widespread in…
Correct answer: None of the above- A. Physical
- B. Biological
- C. chemical
- D. both A & B
Explanation: Chemical soil properties such as pH, cation-exchange capacity and nutrient reactions largely determine whether essential elements remain…
Correct answer: chemical- A. Both A & B
- B. Meso pores & Micro pores
- C. Macro pores
- D. The above statement is wrong
Explanation: Soil pores are commonly classified by size into macropores, mesopores and micropores.
Correct answer: Both A & B115. Depending on the percentage of sand, silt, clay, soils are divided into _______ textural classes:
- A. 12
- B. 13
- C. 14
- D. 09
Explanation: The USDA soil-texture triangle recognizes 12 textural classes, including sand, loamy sand, loam, silt loam, clay loam and clay.
Correct answer: 12- A. Sand
- B. Clay
- C. Silt
- D. None of the above
Explanation: Silt particles are commonly defined as 0.02 to 0.002 mm in diameter in the relevant soil classification scale.
Correct answer: Silt- A. Alfisols
- B. Ultisols
- C. None of the above
- D. Vertisols
Explanation: Vertisols contain large amounts of swelling clay, which expands when wet and contracts into deep cracks when dry.
Correct answer: Vertisols- A. Andisols, Gelisols, Histosols, Spodosols, Oxisols, Ultisols
- B. Entisols, Inceptisols, Aridisols, Alfisols, Mollisols, Vertisols
- C. Andisols, Aridisols, Histosols, Vertisols, Regosols, Libosols
- D. The above statement is wrong
Explanation: The six USDA soil orders commonly recognized in the stated context are Entisols, Inceptisols, Aridisols, Alfisols, Mollisols and…
Correct answer: Entisols, Inceptisols, Aridisols, Alfisols, Mollisols, Vertisols- A. Nitrogen
- B. Potassium
- C. Aluminium
- D. Calcium
Explanation: At very low pH, aluminium becomes soluble and toxic to roots, making it a major growth-limiting factor in acid soils.
Correct answer: Aluminium- A. 24%
- B. 25%
- C. 19.5%
- D. 30%
Explanation: Single superphosphate contains about 19.5% calcium along with available phosphorus and sulphur.
Correct answer: 19.5%