Question

Nitrogen is an essential nutrient for plant growth but farmers who cultivate pulse crops like green gram, bengal gram, black gram, etc. do not add nitrogenous fertilisers to the crops. Why?

• A. These plants produce manure for themselves.
• B. These plants make more nitrogen internally.
• C. Nitrogen kills the bacteria present in root nodules.
• D. The bacteria present in the roots fix nitrogen.

Answer 1

The correct option is D The bacteria present in the roots fix nitrogen.

Roots of pulses (leguminous plants) have a symbiotic association with a bacterium called rhizobium, which fixes atmospheric nitrogen into the soil. Adding more nitrogenous fertilisers make the level of nitrogen in the soil too much for the crops. Hence, farmers need not use nitrogenous fertilisers.