A new method of soil partial sterilization by gamma irradiation was investigated.The result determinating microbial population using plate method showed that significantly declaned in the vital count of bacteria and fungi in soil which after planted rengeng by different done of gamma irradition, and microbial suvival was related to irradiated dose, VIZ. with increasing dose of gamma irradiation there was adecrease.The results of this study also indicated that the leathal dose of gamma irradiation for fungi less than bacteria in soil tested.and it was fund that the critical leathal dose for cylin-drocarpon sp. was 2 Mrad.