It was established, that the increase of a grain yield of spring wheat at diazophit application makes about 8.6 up to 19,8 % depending on the fertilization system. Yield gain by the use of biopreparation was more cost efficient than from the use of mineral fertilizers. Energy efficiency of diazophit inoculation is the largest in the system with the minimal norm of mineral fertilizers. It had exceeded the control on 19,6 %.