The invention relates to mycorrhizal fungi preparations that form arbuscles. To obtain said preparations, a raw inoculum is cultivated on a porous granulate and the raw inoculum that is produced is milled in such a way that the active spores are not destroyed. Said preparations are suitable for fertilisation and crop protection in agriculture and forestry. Glomus sp., and in particular Glomus intraradices are mycorrhizal fungi that are suitable for this application. A hammer/impact mill is used to mill the raw inoculum.