A field experiment was carried out in a randomized complete block design (R.C.B.D) to study the effect of inoculation with R. leguminosarum at two levels (with and without inoculation) and The compost made from the azolla plant and the interaction between them in efficiency of the root nodule formation and growth and yield of the faba bean plant grown in gypsiferous soil after being isolated and identificated by phenotypic, biochemical and molecular methods, the results showed that there was a significant increase in all plant characteristics of the fertilized and inoculated treatments compared to the  non-inoculated treatment, as outperformed the compost treatment with azolla on the control treatment in all growth and yield traits, and significantly superior the inoculation treatment with Rhizobuim leguminosarum  in all studied traits compared to the control treatment,  and gave the inoculation treatment with Rhizobuim leguminosarum and compost made from the azolla the highest values compared to the control treatment, as the averages were in the number of root nodules, their wet weight and number of the bacteria surrounding the roots (15,000, 2.274 and 6.400 x 104), the plant height and the dry weight of the vegetative part (39,000, 24.995), (gm plant-1  cm plant-1 ) and concentration of the nitrogen, phosphorous and potassium in the vegetative part (1487, 238 and 1819) ppm respectively.

In this study 30 samples were collected from the root nodules of Faba bean plants (Vicia faba L.) grown in gypsiferous soil in the College of Agriculture / Tikrit University / Salah al-Din Governorate in 5/12/2020, and the isolation process was carried out on selective mediumYeast Extract Mannitol Agar , and the phenotypically pure isolates were identified based on the culture, microscopic and biochemical characteristics, and the phenotypic identification results showed that 23 isolate gave the characteristics of Rhizobium sp. ,it was color of the colonies between white, cream and yellow, shiny, convex and smooth, gram-negative and most of able to move and has color between light pink and white on Congo red stain medium (0.025%) and it most of fast growing giving them yellow color on bromothymol blue medium and unable to grow on Hofer alkaline medium, and the efficient isolate was selected in the production of indole acetic acid, chelating compounds, and identificated molecularly  by PCR, the 16SrRNA gene was amplified, then the sequence of nitrogenous bases, the results showed that there is a 99.69% similarity with the Rhizobium leguminosarum bv. Viciae strain SMV12a, and therefore the isolate is genetically close to Rhizobium bacteria.