nitrogen cycle- rhizobium bacteria

Rhizobium fixes nitrogen. Rhizobium is found in leguminous plants. The parts you've circled in red are completely separate from Rhizobium though...? You don't need to know specific details about those nitrifying bacteria, just that they can fix nitrogen into organic nitrogen in the soil

There are two kinds of nitrifying bacteria:
1. Those that convert ammonium ions to nitrites e.g. nitrosomonas
2. Those that converts nitrites to nitrates e.g. nitrobacter
As or the part colored blue, I can't read it.
N2 is converted into organic nitrogen in the soil after plant and animal decay (from your figure). So organic nitrogen in the soil here means plant and animal nitrogen containing organic compounds. These might be converted to simpler ones by bacterial degradation, and nitrogen may be converted back to ammonium ions, or to N2 by the action of denitrifying bacteria like Pseudomonas denitrificans.
I hope that helps.

I just realised, I wrote my question out wrong >.< sorry. It must've confused you guys so much, I was really sleepy. I changed it now.

The rhizobium convert atmospheric nitrogen to ammonium ions, but the other nitrogen fixing bacteria in the soil convert atmospheric nitrogen to organic nitrogen and then finally decomposing bacteria convert the organic nitrogen into ammonium ions? Is this correct?

I think I mainly got confused because I researched a bit and they said that nitrogen fixing bacteria converts atmospheric nitrogen into ammonia/ammoinium ions. But maybe they were just talking about some nitrogen fixing bacteria like rhizobium.

Thank you for your help