Q. Consider the following statements about how plants absorb nitrogen:

1. Plants absorb nitrogen in the form of inorganic nitrates or nitrites.
2. Plants take in nitrogen in the form of organic compounds.
3. Nitrogen is directly taken up by the plants from the atmosphere.

Which of the above statements is / are correct?
Answer: Only 1 and 2
Notes: Plants obtain nitrogen through their roots. In the soil, nitrifying bacteria change ammonia into nitrite (NO2 –) and then into nitrate (NO3 –), this process is known as nitrification. Furthermore, plants also absorb nitrogen in an organic form. Several organic compounds (compounds containing carbon) constitute the organic fraction of nitrogen in the soil. The organic matter in the soil exists as decomposing plant and animal residues, relatively stable decomposition-resistant compounds, and humus. The abundance of various forms of nitrogen can be altered by plant roots through the change in pH and secretion of organic compounds or oxygen.