PURPOSE: To prevent the drought and fertilizer deficiency of soil as well as run- off of the soil by a method in which perforated pipes into which water-holding fibers and slow-acting solid fertilizers are housed are laid on rocky slope and buried by soil to form convexed soil layers.

CONSTITUTION: A packing material 2 consisting of water-holding fibers and slow acting solid fertilizers is housed into a perforated pipe 1 having countless water- passing holes on its periphery. The pipes 1 are plurally laid sideways in parallel on a rocky slope 11 and fixed. Soil mixed with humus and plant seeds is then sprayed on the rocky slope 11 to form a soil layer 13. In this case, the perforated pipe 1-buried portions in the soil layer 13 are healed beyond the other portions to form convexed portions 13a. The drought and fertilizer deficiency of the soil layer 13 can thus be prevented, and the run-off of the soil layer 13 can be prevented by the convexed portions 13a.