AGR491 CHAPTER 1

What is the definition of soil according to plant scientists?

• Engineering materials supporting roads and buildings

• A medium for plant growth which provides nutrients and water

• The uppermost part of the earth’s crust in which water is flowing

• A productive artificial media for growing crops

Which horizon is known as the organic layer in soil?

• Horizon C

• Horizon O

• Horizon B

• Horizon A

What is the primary material from which soils are formed called?

• Soil profile

• Parent material

• Soil horizon

• Soil pedon

Which of the following is NOT a factor influencing soil development?

• Planting

• Additions

• Translocations

• Losses

What does the term 'luxury consumption' refer to in plant nutrition?

• Absorbing nutrients below the critical range

• Absorbing nutrients above the maximum yield requirement

• Absorbing only essential nutrients

• Absorbing no nutrients at all

According to Sprengel & Liebig’s Law of the Minimum, what happens when the most limiting nutrient is corrected?

• Yield will remain the same

• Yield will increase to a level limited by another nutrient

• Yield will be maximized immediately

• Yield will decrease

Which of the following elements is considered a macronutrient?

• Iron (Fe)

• Zinc (Zn)

• Nitrogen (N)

• Copper (Cu)

What is the role of soil as a regulator of water supply?

• It prevents water from entering the soil

• It allows water to flow away quickly

• It helps water get into good soils after rainfall

• It stores all water without any loss

What is the significance of the E horizon in soil profiles?

• It is the parent material

• It is the zone of accumulation

• It is the organic layer

• It is the zone of greatest eluviation

Which of the following statements best describes the role of soils in recycling raw materials?

• Soils prevent nutrient loss

• Soils only store nutrients

• Soils turn organic wastes into humus

• Soils do not play a role in recycling