Six substrates made up with heated and composted anaerobic biosolid were tested for the production of Eucalyptus viminalis, Schinus terebinthifolius and Mimosa scabrella forest seedlings in a nursery in Southern Brazil. The produced seedlings were statistically evaluated in relation to height, stem diameter, height/stem diameter ratio, aerial and root dry biomass, survival, and also for nutritional status on S. terebinthifolius seedlings. As a function of their high pH, heated biosolids turned out to be viable only in low composition percentages. Composted biosolids turned out to be sufficiently suitable in percentages between 30% and 60% of the substratum - whose Mn and Zn concentrations relate the nutrient contents in the seedlings Ðwith use viability up to 100% in substratum composition.