PURPOSE: To improve the growth of vegetation products, by providing a substrate, with a bag unit containing dry soil activator compounded with substance including the respective specified percentage or more of humus acid and protein nitrogen and with the culture substance of bacillus germ and actinomyces.

CONSTITUTION: Substance including humus acid of 10% or more and protein nitrogen of 1% or more is compounded with the culture substance of bacillus germ and Actinomyces, to form dry soil activator 1. The soil activator 1 is contained in a bag unit 2, and the bag unit 2 is fitted on a tree planting substrate on the surface of slope. If required, one kind or more of the vegetation block materials of nitrogen slow-release fertilizer, humus acid containing substance, compound fertilizer, organic substance, water-holding material, soil improving agent, vegetation seeds, and the like are added to the soil activator 1.