Question
what is the background of biofertilizer? can U give me detail about azatobactor&Rhizobium

Answer
Azotobacter vinelandii is Nitrogen fixing Bacteria that lives in Soil.  It is important because it can fix Nitrogen all by itself.  Rhizobium cannot; Rhizobium is unique because it depends on plants called 'Legumes' to work with it.  All about Azotobacter Bacteria:

azotobacter.org/

'Azotobacter vinelandii is a large, obligately Aerobic Soil Bacterium which has one of the highest respiratory rates known among living organisms and is able to grow on a wide variety of carbohydrates, alcohols and organic acids, in addition to be able to fix Nitrogen. A. vinelandii has been intensely studied for many years because of its ability to ... fix nitrogen in air.... A. vinelandii can form unique cysts that survive desiccation and the organism produces polymers of carbon for storage... A. vinelandii is highly amenable to genetic manipulation....Among its unique abilities are the capacity to fix, or reduce, atmospheric nitrogen gas (N2) to compounds of ammonium (NH4+)... This organism recycles the Hydrogen produced as a byproduct of Nitrogen fixation thereby increasing its efficiency...it can do this under conditions of atmospheric oxygen supply (20 percent), in contrast to other diazotrophic Bacteria which must fix Nitrogen either anaerobically or microaerobically.'

All about Rhizobium:

www.bionewsonline.com/y/what_is_rhizobia.htm

'Rhizobia (from the Greek words Riza = Root and Bios = Life) are Soil Bacteria that fix Nitrogen ('diazotrophy') after becoming established inside root nodules of legumes ('Fabaceae')...There are several different genera of Rhizobia...Soil Microbiota communities have demonstrated their crucial role in maintaining the Soil ecological balance and therefore the sustainability of either natural ecosystems or agroecosystems.  Rhizospheric microbe-plant interactions have a great influence on plant health and Soil quality since these root-associated microorganisms are able to help the host plant to deal with drought, nutritional and Soil-borne pathogen stress conditions...'

I could go on for hours and get even more technical.  Tell me what you need to know specifically.

THE LONG ISLAND GARDENER