Which of the following are nitrogen-fixing plants?

1. Alfalfa
2. Amaranth
3. Chickpea
4. Clover
5. Purslane (Kulfa)
6. Spinach

Select the correct answer using the code given below:

[UPSC Civil Services Exam – 2022 Prelims]

(a) 1, 3 and 4 only

(b) 1, 3, 5 and 6 only

(c) 2, 4, 5 and 6 only

(d) 1, 2, 4, 5 and 6

Answer: (a)        

Explanation:

• Nitrogen fixation is the process of converting atmospheric nitrogen (N2) into more reactive compounds such as ammonia, nitrites, and nitrates.
• Nitrogen-fixing plants are crops that can naturally provide plant-available nitrogen without causing harm to the environment.
  • Some examples of nitrogen-fixing plants include clovers, vetches, and peas, which are commonly used by farmers worldwide and in the US Southern Great Plains region.
  • Peas and beans are versatile nitrogen-fixing crops that can be used as cover crops during summer or harvested for food, both of which can enrich the soil with plant-suitable nitrogen. Southern peas prefer warmer seasons and are typically sown when the soil temperature reaches 60°F.
  • Various types of beans, such as fava, alfalfa, green, runner, field, sweet, peanuts, soybeans, cream, black-eyed, or purple-hulled beans, lupins, lentils, and cowpeas, are also nitrogen-fixing plants.