1. What does soil pH measure?

• Soil’s temperature
• Soil’s acidity or alkalinity
• Soil’s organic content
• Soil’s moisture level

2. What pH value is considered neutral?

• 6.0
• 7.0
• 8.0
• 9.0

3. What is the pH range preferred by most plants?

• 4.0 to 5.0
• 5.5 to 7.0
• 7.0 to 8.0
• 8.0 to 9.0

4. What kind of environment does a high positive Eh indicate?

• Reducing environment
• Oxidizing environment
• Neutral environment
• Alkaline environment

5. Which of the following ions are not retained by soil colloids?

• Potassium (K+)
• Ammonium (NH4+)
• Calcium (Ca++)
• Nitrate (NO3-)

6. What is Cation Exchange Capacity (CEC)?

• The soil’s ability to retain water
• The soil’s ability to retain cations
• The soil’s acidity level
• The soil’s organic content

7. Which of the following soils tend to have a higher CEC?

• Sandy soils
• Clay soils
• Silty soils
• Loamy soils

8. What does a low negative Eh indicate?

• High oxidizing environment
• Neutral environment
• Strong reducing environment
• Alkaline environment

9. Which element’s availability is most affected by soil pH between 6.0 and 7.5?

• Nitrogen
• Phosphorus
• Potassium
• Calcium

10. In the context of soil chemistry, what is the significance of redox potential (Eh)?

• It measures soil temperature
• It measures soil acidity
• It indicates the soil’s tendency to oxidize or reduce substances
• It measures soil moisture

11. How is the reduction potential (E0) of a species defined?

• Relative to the standard hydrogen electrode
• Relative to the standard oxygen electrode
• As an absolute potential
• As a fixed value of 1.0 volts

12. What happens to the acid content of soil when the pH is lowered from 6.5 to 5.5?

• It increases 2-fold
• It increases 5-fold
• It increases 10-fold
• It increases 100-fold

13. What is the role of buffering solution in the Buffer pH (BpH) test?

• To increase soil acidity
• To maintain pH stability
• To simulate fast-acting lime
• To measure soil moisture

14. Which ions are typically more soluble in acid soils?

• Calcium and magnesium
• Sodium and potassium
• Iron and aluminum
• Sulfate and chloride

15. Which nutrient is commonly associated with deficiencies in alkaline soils?

• Nitrogen
• Phosphorus
• Iron
• Potassium

16. Which factor most strongly influences soil pH?

• Soil color
• Soil temperature
• Soil parent material
• Soil texture

17. What is the main source of acidity in soils?

• Carbon dioxide
• Organic acids
• Aluminum ions
• Nitrate ions

18. Which process contributes to soil acidification?

• Liming
• Leaching of bases
• Soil compaction
• Soil erosion

19. Which ion exchange is considered an important reaction in the soil environment?

• Ca2+ for Na+
• Ca2+ for Mg2+
• H+ for Ca2+
• K+ for Na+

20. Which condition increases the concentration of hydrogen ions (H+) in soil?

• Increasing pH
• Decreasing pH
• Adding lime
• Adding organic matter

21. Which soil component contributes most to cation exchange capacity (CEC)?

• Sand
• Silt
• Clay
• Gravel

22. What is a common symptom of aluminum toxicity in plants?

• Yellowing of leaves
• Stunted root growth
• Leaf curling
• Wilting

23. Which soil pH level is considered highly alkaline?

• 6.5
• 7.5
• 8.5
• 9.5

24. How does soil pH affect microbial activity?

• Low pH enhances microbial activity
• Neutral pH favors microbial activity
• High pH inhibits microbial activity
• Low pH inhibits microbial activity

25. What is the function of soil organic matter?

• It increases soil compaction
• It improves soil structure
• It decreases water retention
• It reduces nutrient availability

26. Which soil amendment is used to lower pH in alkaline soils?

• Lime
• Gypsum
• Sulfur
• Compost

27. How does soil organic matter affect soil pH?

• It increases pH
• It decreases pH
• It buffers pH changes
• It has no effect on pH

28. Which gas is released during the reduction of nitrate in soils?

• Oxygen
• Nitrogen
• Hydrogen
• Carbon dioxide

29. What is the main source of nitrogen for plants?

• Atmospheric nitrogen
• Soil organic matter
• Soil minerals
• Irrigation water

30. Which form of nitrogen is most readily available to plants?

• Nitrogen gas (N2)
• Ammonium (NH4+)
• Nitrate (NO3-)
• Nitrite (NO2-)

31. Which process converts ammonium to nitrate in soils?

• Nitrogen fixation
• Denitrification
• Mineralization
• Nitrification

32. What is the significance of soil pH in nutrient availability?

• pH has no effect on nutrient availability
• pH only affects nitrogen availability
• pH affects the availability of all nutrients
• pH affects the availability of water

33. How does high soil pH affect phosphorus availability?

• It increases phosphorus availability
• It decreases phosphorus availability
• It has no effect on phosphorus availability
• It increases phosphorus leaching

34. What does a low soil pH indicate about the concentration of hydrogen ions (H+)?

• Low concentration of H+
• High concentration of H+
• No H+ present
• H+ concentration does not change

35. What is the primary effect of soil acidification on nutrient availability?

• It increases the availability of all nutrients
• It decreases the availability of all nutrients
• It increases the availability of some nutrients and decreases others
• It has no effect on nutrient availability

36. Which soil pH level is optimal for most crop plants?

• 4.5 to 5.5
• 5.5 to 6.5
• 6.5 to 7.5
• 7.5 to 8.5

37. Which element becomes more toxic as soil pH decreases?

• Calcium
• Magnesium
• Aluminum
• Potassium

38. What is the effect of liming on soil pH?

• It decreases soil pH
• It increases soil pH
• It has no effect on soil pH
• It neutralizes soil pH

39. Which soil property does the Buffer pH (BpH) test evaluate?

• Soil texture
• Soil moisture
• Soil acidity
• Soil organic matter

40. Which soil pH is considered optimal for legume crops?

• 4.5 to 5.5
• 5.5 to 6.5
• 6.5 to 7.5
• 7.5 to 8.5

41. Which ion is predominantly exchanged in the cation exchange process in acidic soils?

• Sodium (Na+)
• Calcium (Ca2+)
• Hydrogen (H+)
• Magnesium (Mg2+)

42. Which factor does not directly affect the redox potential (Eh) of soil?

• Soil temperature
• Soil moisture
• Soil organic matter
• Soil texture

43. Which ion is most commonly associated with soil salinity?

• Nitrate (NO3-)
• Calcium (Ca2+)
• Sodium (Na+)
• Magnesium (Mg2+)

44. Which process increases the alkalinity of soil?

• Leaching of bases
• Addition of organic matter
• Application of ammonium-based fertilizers
• Liming

45. Which element is typically more available in acidic soils compared to alkaline soils?

• Calcium
• Magnesium
• Iron
• Potassium

46. What is the effect of soil compaction on soil aeration?

• It improves soil aeration
• It decreases soil aeration
• It has no effect on soil aeration
• It only affects water retention

47. Which nutrient is often deficient in acidic soils?

• Manganese
• Copper
• Zinc
• Calcium

48. What is the primary cause of soil salinity?

• Excessive irrigation
• Heavy rainfall
• Application of lime
• Crop rotation

49. Which soil amendment is used to improve soil structure and water retention?

• Sand
• Gypsum
• Peat moss
• Compost

50. Which process decreases soil acidity?

• Leaching of bases
• Addition of organic matter
• Application of sulfur
• Liming