PURPOSE: To provide the titled conditioner which does not cause salt damage due to the accumulation of salts nor growth retardation by continuous cropping, containing an anionic surfactant having hard water resistance and biodegradability and a specified water-soluble protein.

CONSTITUTION: 100pts.wt. anionic surfactant (A) having hard water resistance and biodegradability (e.g. sodium dodecylbenzenesulfonate) and 20W60pts.wt. water-soluble protein (B) (e.g. glue) obtd. by boiling scleroprotein (e.g. hide and skin or nail) in water for many hours, are dissolved in water in such a proportion that the soln. contains component A at a concn. of 0.2W0.02wt%.

EFFECT: The soil conditioner has effects of reducing phosphate salt absorption coefficient, reactivating deactivated fertilizer accumulated in soil, forming crumbs and groving soil microorganism so that the growth and the crop of cultural vegetables can be increased.