nitrogen fixing nodules forming in gritty mix
In 2008 I planted a silk tree (Albizia julibrissin) from seed in miracle grow potting mix. In 2010 I repotted into the gritty mix, and was surprised to see a few nitrogen fixing nodules in the roots. I knew this was a nitrogen fixing species, but I had made no attempt to inoculate the medium with the necessary bacteria. Somehow they got in there. I assumed there were some in the mix.
Yesterday I repotted again. The root ball was a big mass of mostly fibrous roots, and I saw a lot of nodules, many more than before. I would not have guessed that the gritty mix would support free living rhizobium needed for nodulation, but apparently it does.
Has anyone else seen nodule formation in gritty mix, with or without inoculation?