Spent compost of Agaricus bisporus were used in forest nursery for Brutia pine (Pinus brutia Ten.) seedlings by 1/4 to 3/4 ratios mixed by soil. Results indicate that after picking up fresh mushroom yielded 5.5 Kg/m2 the spent compost can be used in forest nurseries as organic fertilizer. Plant properties of grown seeds were found as much as higher approximately 20 % in the presence of spent compost with soil in some mixtures to soil solely.