My dear friend a floode paddy field is having anaerobic conditions and I think you are looking for aerobic microbes there. Yes, the only aerobe that you may find will be Azotobacter spp (it all depends). You will get organisms capable of using Hydrogen as an energy source and convert carbon dioxide to methane (small quantity) and other organic compounds. Herbicide degraders are usually aerobic and naturally they may be present in very low numbers.

Dear Paawan,

The no. of the aerobic microorganisms inhabiting in any soil is far greater that those of anaerobic microorganisms. Under anoxic environment (flooded condition), the activities of the aerobic microorganisms get reduced in the absence of molecular oxygen thereby, declining the overall microbial activities. See the below papers for further help.

Best regards

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0166349

The absence of oxygen under the flooded condition will not allow the presence of aerobic

soil bacteria such as pseudosomonas ,nitrosomonas, and nitrobacter which are important in nitrogen cycle by converting organic N to nitrite and nitrate nitrogen but under flooded condition Rhidospirilus bacteria willconvert nitrate nitrogen in elemental N and escapes into the air besides, the anaerobic organisms will produce more sulphur, methane,gases which constitute green house gases that causes depletion of ozone layer and the subsequent effect on climate

Very often , anoxia like conditions discourage heavily the microbes to proliferate in paddy  field...

Flooded conditions will only favour anaerobic organisms which are usually very few.

Also remember fungi are strictly aerobes.