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Q106 (IAS/1994) Environment & Ecology › Ecology & Ecosystem Basics › Sustainable agriculture Answer Verified

Which of the following is/are used as biofertilizers ? I. Azolla II. Blue-green algae III. Alfalfa. Select the correct answer using the codes given below.

Result
Your answer: —  Â·  Correct: B
Explanation

Biofertilizers are defined as preparations containing live strains of nutrient‑mobilizing microorganisms (e.g., nitrogen‑fixers) applied to seeds or soils to increase microbial processes that make nutrients available to plants [1]. Blue‑green algae (cyanobacteria) are explicitly listed among nitrogen‑fixing microbes used as biofertilizers [2]. Azolla, an aquatic fern with a symbiotic nitrogen‑fixing cyanobacterium (Anabaena), has long been used as a biofertilizer/green manure in rice cultivation because of its rapid N‑fixation and mass production potential. Alfalfa, by contrast, is a leguminous crop/forage plant (not a microbial preparation) and is not classified as a biofertilizer per the definition in [1]. Therefore, I and II are used as biofertilizers.

Sources

  1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 25: Agriculture > Bio-fertilizers > p. 364
  2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > s r n r u l z N ,- / & f . -. : : u ' , \ S ACADEMY * d 6 # . , r '' t u f Y l ' ' J * w { d ) / u Y . / > p. 20
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SIMILAR QUESTIONS

IAS · 2013 · Q8 Relevance score: 3.61

Consider the following organisms: 1. Agaricus 2. Nostoc 3. Spirogyra Which of the above is/are used as biofertilizer / biofertilizers?

IAS · 2010 · Q57 Relevance score: 2.45

Which feature of some species of blue green algae helps promoted them as bio-fertilizers?

IAS · 2000 · Q115 Relevance score: 1.51

Which one of the following organisms can serve as a biofertiliser for rice crop?

CDS-II · 2010 · Q24 Relevance score: 0.83

Which among the following statements about bio fertilizers are correct ? . 1. Azotobacter is one of the Nitrogen fixing bacteria used as a bio fertilizer. 2. They have to be applied to the leaves of the plant only. 3. They alter the chemical composition of the soil. 4. They can be used along with organic fertilizers. Select the correct answer using the code given below :

NDA-II · 2018 · Q55 Relevance score: 0.05

Which one of the following is not used as fertilizer?