The invention relates to a method of biological soil decontamination, comprising the introduction, into the soil, of a product that contains a material chosen from a group consisting of proteins, carbohydrates and lipids, which product does not contain any unprocessed fresh plants or unprocessed fresh plant residues, the method in question also comprising the application of a barrier layer between the soil and the air. Biological soil decontamination by the method according to the invention is faster and more reliable. Biological soil decontamination by the method according to the present invention can also lead to an increased yield.