Sludge is the ultimate by product of all traditional and conventional wastewater treatment processes. Conversion of the treatment sludge into new products is a significant disposal alternative for these wastes. In this study, branches, leaves and the organic and inorganic trash coming out from the aerated sand trap unit have all been mixed up with determined mixing ratios and composting has been realised by windrow-composting technique. The present study was conducted to investigate the effects of 4 different treatment sludge composts and chemical fertilizer on soil characteristics and plant (oat and grass) yields. Experiments were conducted in randomized black design with 3 replications in a plastic high-tunnel greenhouse. The sludge composts of sample1 (S1) and sample2 (S2) were applied at rates of 4 t/da and 6 t/da. Chemical fertilizer was applied in the form of N8P6. Grass was sown in a rate of 20 gr m(-2). Oat was sown in pots at a rate of 60 seeds per pot and then thinned to have 40 plants in each pot. Sludge composts in grass and oat culture significantly improved soil characteristics and increased the plant yields. It was concluded that sludge composts could be used as an alternative soil amendment.