PURPOSE: To easily obtain a slow-acting solid fertilizer which activates the propagation of actinomycetes, etc., in soil, accelerates the rooting and germinating of plants and has excellent handling quality by mixing dried and pulverized crab shells and glue into fibrous vegetable main materials and subjecting the mixture to dehydration drying, then solidifying and forming the mixture to arbitrary shapes.

CONSTITUTION: The crab shells 2 formed by drying and finely pulverizing the shells of the crabs obtd. as waste during the course of fish processing are incorporated into the vegetable main materials M, such as paper, pulp and straws, which are finely pulverized to a fibrous form. The water and the glue 3 to adhere these materials are mixed with the materials and, thereafter, the materials are subjected to dehydration drying and are solidified and formed to the desired shapes, by which the base material 1 as the solid fertilizer is obtd.