Environmental Studies · Biology

Soil Science and Fertilizers

1,537 Questions

Soil science focuses on soil formation, classification, and fertility management using fertilizers and organic amendments. Agricultural and environmental science exams heavily feature questions on biofertilizers, mycorrhiza, and phytoremediation. Practice these questions to build a strong understanding of soil nutrient cycles.

Phytoremediation techniquesOrganic soil amendmentsBiofertilizers and mycorrhizaNitrous oxide emissionsIn-situ soil remediationGreen manuring effects

Soil Science and Fertilizers Questions

Multiple choice

Decomposition of organic matter is brought about by

  1. protozoa

  2. plants

  3. micro-organisms

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Decomposition of organic matter (dead plants, animals, waste) is primarily carried out by microorganisms including bacteria and fungi. These saprotrophs break down complex organic molecules, recycling nutrients back into the ecosystem. Protozoa contribute to but don't drive decomposition.

Multiple choice

Directions: For this question, select the best of the answer choices given.

Two experimental garden plots were each planted with the same number of tomato plants. Magnesium salts were added to the first plot but not to the second. The first plot produced 20 pounds of tomatoes and the second plot produced 10 pounds. Since nothing else but water was added to either plot, the higher yields in the first plot must been due to the magnesium salts. Which of the following, if true, most seriously weakens the argument above?

  1. A small amount of the magnesium salts from the first plot leached into the second plot.

  2. Tomato plants in a third experimental plot, to which a high-nitrogen fertilizer was added, but no magnesium salts, produced 15 pounds of tomatoes.

  3. Four different types of tomatoes were grown in equal proportions in each of the plots.

  4. Some weeds that compete with tomatoes cannot tolerate high amounts of magnesium salts in the soil.

  5. The two experimental plots differed from each other with respect to soil texture and exposure to sunlight.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The argument incorrectly assumes magnesium salts caused higher tomato yields while ignoring other potential variables. Option E seriously weakens this by showing the plots differed in soil texture and sunlight exposure - factors that significantly affect plant growth. If the plots weren't comparable except for magnesium, the conclusion is invalid. Options A, B, C, and D don't address the core comparability issue: leaching would affect both plots (A), nitrogen fertilizer results don't weaken the magnesium conclusion (B), tomato types being the same supports rather than weakens (C), and weed intolerance doesn't challenge the magnesium effect (D).

Multiple choice

Potassium is taken by plants from the soil in the form of:

  1. potassium chlorate

  2. potassium hydroxide

  3. potassium nitrate

  4. can be in any form
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plants absorb potassium from soil primarily in the form of potassium ions (K+), commonly found in potassium nitrate (KNO3), potassium phosphate, or other soluble potassium salts. Potassium nitrate is a common fertilizer source. Potassium chlorate is toxic to plants, and potassium hydroxide is too alkaline.

Multiple choice

Characteristic smell of onion bulb is due to the presence of:

  1. lipid content

  2. reserve carbohydrates

  3. sulphur compounds

  4. bad odour of soil in which they are cultivated.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Onions contain organosulfur compounds like allyl propyl disulfide that produce their characteristic pungent smell when cells are damaged. These sulfur-containing compounds are secondary metabolites that give Allium vegetables their distinctive aroma and flavor.

Multiple choice

Which of the following functions is not performed by roots?

  1. Taking minerals from soil.

  2. Helping in the prevention of erosion.

  3. Making food for plant.

  4. Giving strength to the plant.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Roots perform several essential functions: they absorb water and minerals from soil (option A), anchor the plant and provide strength (option D), and help prevent soil erosion (option B). However, roots do NOT make food - that function is performed by leaves through photosynthesis. Therefore, making food for the plant is the correct answer as it is NOT a root function.

Multiple choice

Legume plants are important for atmosphere because they

  1. help in NO2 fixation

  2. do not help in NO2 fixation

  3. increase soil fertility

  4. Both (1) and (2)

  5. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Legume plants are important for atmosphere because they help to increase the fertility of soil by fixing nitrogen in the soil. 

Multiple choice

Bioremediation is the use of microbes to clean up contaminated soil and groundwater. Which among the following fern is used as a potential bioremediation plant for absorbing arsenic from the soil?

  1. Vegetable fern

  2. Licorice fern

  3. Brake fern

  4. Tree ferns

  5. C-fern
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Brake fern was discovered to have the ability to "hyperaccumulate" (absorb large amounts of) arsenic from soil. The fern was growing at a central Florida site contaminated with large amounts of copper arsenate in the soil. The discovery may lead to the use of this fern as a potential bioremediation plant.

Multiple choice

Which of the following statements is/are correct?

a. In the gaseous cycle, the main reservoir of nutrients is the atmosphere and the ocean. b. In the sedimentary cycle, the main reservoir is the soil and the sedimentary and other rocks of Earth’s crust. c. These biogeochemical cycles are largely energised by solar insolation.

  1. a only

  2. b only

  3. c only

  4. a and b

  5. a, b and c
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct answer as all the given statements are correct.

Multiple choice

Natural gas is the main feed stock for fertilizer industry, the price of Natural gas supplied to fertilizer industry does not seem to reflect its true cost.

  1. Natural gas is the main feed stock for fertilizer industry and its supply price does not seem to reflect its true cost.

  2. Natural gas is the main feed stock for fertilizers industry and the price of Natural gas supplied to it does not seem to reflect its true cost.

  3. Natural gas is the main feed stock for fertilizer industry, the price of Natural gas supplied to fertilizer industry does not seem to reflect its true cost

  4. The main feed stock for fertilizer Industry is Natural gas and its supply to them does not seem to reflect its true cost.

  5. Natural gas is the main feed stock for fertilizer industry whose supply price does not seem to reflect its.

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

n 'it' for industries, whose industry is a collective noun, hence its incorrect, options (E) and (D) have wrong phrasing hence (A) is the correct answer.

Multiple choice

Select the biofertilizer in the following

  1. Compost

  2. Ammonium sulphate

  3. Cattle dung

  4. Algae and blue-green algae
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Algae and blue-green algae (cyanobacteria) are biofertilizers as they fix atmospheric nitrogen and enrich soil fertility. Compost and cattle dung are organic manures, not biofertilizers. Ammonium sulphate is a chemical fertilizer. Biofertilizers are living microorganisms that enhance nutrient availability.

Multiple choice

Maximum biological activities occur in ________ of the soil.

  1. horizon A

  2. horizon B

  3. horizon O

  4. horizon C
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Horizon A (topsoil) contains the highest organic matter, humus, and root density, supporting maximum biological activity including decomposition, nutrient cycling, and soil organism activity. This is where most plant roots and soil organisms are concentrated.

Multiple choice

Legitimately, an average garden soil consists of

  1. 70% minerals, 10% water and 10% organic matter

  2. 50% minerals, 40% organic matter, 10% water and 20% H2O

  3. 40% minerals, 25% water, 10% organic matter and 25% air

  4. Any of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ideal garden soil composition includes approximately 45% minerals, 25% water, 25% air, and 5% organic matter. Option C with 40% minerals, 25% water, 25% air, and 10% organic matter is closest to this standard. Options A and B have incorrect percentages, and option D is vague.