Which graph shows the presence of nitrogen-fixing bacteria in the soil

Graph 2 represents the presence of nitrogen-fixing bacteria in the soil.

This is because in this graph the concentration of atmospheric nitrogen (N2) is lower and the concentration of ammonium (NH4) is higher. The nitrogen-fixing bacteria converts or fixes atmospheric nitrogen that can't be absorbed by the plants into ammonium or nitrates which can be absorbed by the plants and make necessary amino acids for the body so we can conclude that graph 2 indicates the presence of nitrogen-fixing bacteria in the soil.

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the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus