PURPOSE: To sharply increase absorption of a fertilizer to seeds sprayed to a slope, by a method wherein a specified soil improving material is mixed with water to bring it into a muddy state, and the mixture is sprayed to a slope.

CONSTITUTION: A soil improving material, which is prepared by culturing and breeding an actinomyces and a bacterium in one or more types of seeds of pasture seeds, wild grass seeds, and tree seeds, an organic material such as bark compost, peat moss, and a vermiculite, is mixed with a chemical fertilizer and earth, where neccessary, and water is added to bring it into a muddy state to spray it to a slope by a motor-operated sprayer.