Intercropping berseem clover (Trifolium alexandrinum L.) may increase forage yield and free-living N2-fixing bacterial species community. Berseem clover was mixed with Persian clover (Trifolium resupinatum L.) at ratios of 1:0, 3:1, 1:1 and 1:3 and with Persian clover/ annual medic (Medicago regidula cv. Regidula) at ratio of 1:1:1 at Field Crops Department, Faculty of Agriculture, Tarbiat modares university, Tehran, Iran in 2007. Mixed ratio had significant effect on total forage yield. Total forage yield was greatest with a 1:1:1 ratio of clovers to annual medic. Total intercrop yields with clovers/ annual medic at 1:1:1 plants m–2 was 214.37g m–2 DM yields. Mixed cropping increased rhizosphere microorganisms viz. bacteria, free-living N2-fixing bacteria and Azotobacter counts. Free-living N2-fixing bacterial species and Azotobacter populations of 96 g-1 soil*103 cells and 24 g-1 soil*102 cells, respectively, obtained from mixed cropping with 1:1:1 clovers to annual medic ratios
