Abstract: A process for biodegradation of crude oil wastes and for recovery of contaminated land including the steps of extracting sludges containing the wastes, collecting the sludges into a container, mixing an alkaline salt with the sludges so as to react the salt with the sludges under a generally constant degree of humidity, adding black earth to the mixed alkaline sludges so as to neutralize the alkaline sludges and to degrade the oil wastes through chemical reactions, adding a material to the neutralized sludges so as to enrich the sludges, and forming a humus of the neutralized sludges by the organic degradation of the neutralized sludges through fermentation or putrefaction. The material added to the neutralized sludges so as to enrich the sludges can be selected from the group including sawdust, rice husks, sugar cane bagasse, and animal excrement.