To clarify the proper and safe duration of maturation periods for sawdust　pig manure composts, leaf lettuces were applied with pig manure composts fermented for 15, 30, 45, 60, 75 days and 1 year (control) and cultivated in a plastic house with or without additional PE film tunnel. The changes in physiochemical properties of soil and leaf lettuce growth were measured. Shorter duration of maturation periods enhanced the generation of NH₃ gas from the composts and resulted in significant decrease in seed germination, growth and yield of leaf lettuce. Under with and without PE tunnel conditions the concentration of NH₃ from compost over 3.8 and 2.1 ㎎/100g composts, respectively induced growth reduction. In proportion to the increase of maturation duration saw　dust containing pig manure exhibited decrease in C/N ratio, NH₄⁺　N, NH₄⁺/NO₃ ratio but increase in NO₃ N contents. In case of applying pig manure compost without PE film tunnel condition the minimum maturation period of pig manure composts for safe leaf growth was 60 days, while minimum 75 days of maturation was required when applied with PE film tunnel.