Abstract
This research was done in order to study of effect the soil humidity on earthworm Pontoscolex corethrurus biomass. 80 earthworm were placed in plastic pot (12.5 cm in diameter an 10 cm on deep) contained soil media (four individuals in each pot). Four treatment of humidity (45 %, 5 %, 55 % and 60%) with five replication was carried out up to six weeks. At the end of experiment animals were wighting. The difference between pre and post experimental body weigh was calculated, F test was used to test biomass differences among the four condition of humidity. The result shown that the optimum biomass was in 50% soil humidity in the soil media.