PURPOSE: To provide a basal technique for preparing the ground capable of promoting vegetation on sandy ground such as a sandhill or desert, intended to maintain the water holding ability of the resultant prepared land for a long period of time to prevent its drying and feed plants with water very slowly with no concomitant salt accumulation.

CONSTITUTION: A material or structure having both water holding ability and air permeability is prepared pref. in a columnar form in part of a sandy ground. This material or structure is pref. fine granule-aggregated structure, fibrous assembly, simple form of plant stems or aggregate thereof, lamellar form of polymer, rolled form of sheetlike material, bound form of fibers or plants, or timbers; the preparation technique is as follows: when the advancing part is pulled out of the tip of the hollow advancing component of a digger, said material or structure is inserted into the resultant bores, thus providing prepared area in part of the sandy ground.