Abstract: This invention relates to a process and compositions for conditioning soils. More particularly, it relates to an improvement in the soil conditioning properties of known polymers.In the process according to the invention for conditioning soils, the soil is treated with an iron salt and at least one polymer which does not require a pH greater than about 7 for it to harden, in the presence of a protein substance.The iron salt is preferably selected from ferrous sulphate, ferric sulphate, ferric chloride and mixtures thereof.The polymer is at least one polymer selected from the resins of the aminoplast type, polyurethanes, polyvinyl alcohol which may be urethanized, potassium polystyrene sulphonate, maleic acid-vinyl acetate copolymers, polyvinyl acetate, polybutadiene, synthetic rubbers, natural rubber latex and asphaltic bitumen. The preferred polymer is a urea-formaldehyde resin which may be mixed with urea in a free condition or a polyurethane.