The invention relates to the production and use of environmentally friendly liquid organic biofertilizer for soils and/or plants which is colonized by natural soil microorganisms. It is proposed the method in which, due to the optimal processing of a starting humus-containing soil or soil mixture colonized by natural soil microorganisms with applying the proposed “soft” controlled turbulence action without cavitation effects, the conditions for preserving and reproducing the natural soil microorganisms in their natural medium are provided, as a result it is obtained the final product in the form of a homogenous fine-dispersed suspension, which contains the solids of 10-50 microns size. This product is mainly composed of water-soluble nitrogen (preferably 40 mg/100 g fertilizer) and water-soluble carbon (preferably 470 mg/100 g fertilizer) and is suitable for packaging and long-term storage. The claimed biofertilizer is uniformly colonized by the hardened natural soil microorganisms which are in the state of anabiosis and spore forms, their concentration being at its maximum. The proposed treating soil, seeds or plants with using this biofertilizer results in higher crop yields, improved fertility of depleted soils and restored fertility of sandy and sandy-loam soils.