A farmer in Trinidad stops using nitrogen fertilisers and instead plants leguminous crops such as pigeon peas. Which organism makes this strategy effective for restoring soil nitrogen?

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Question

A farmer in Trinidad stops using nitrogen fertilisers and instead plants leguminous crops such as pigeon peas. Which organism makes this strategy effective for restoring soil nitrogen?

Accepted Answer

Rhizobium bacteria in the root nodules — Rhizobium bacteria live in the root nodules of leguminous plants and fix atmospheric nitrogen (N₂) into ammonia, which is then converted to nitrates that plants can absorb. Nitrobacter performs nitrification in soil but does not fix N₂. Pseudomonas is a denitrifier that removes nitrogen from the soil. Aspergillus is a fungus involved in decomposition, not nitrogen fixation.

Answer

Pseudomonas bacteria in the root nodules

Answer

Rhizobium bacteria in the root nodules

Answer

Nitrobacter bacteria living freely in soil water

Answer

Aspergillus fungi attached to the root surface

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