The utilization of municipal organic wastes in agricultural fields is gaining popularity as a waste disposal method and source of organic matter. Most sewage wastes contain valuable nutrients that could be used to improve soil fertility. Furthermore, beneficial changes may be seen not only in the chemical but also in the physical properties of soil. A field experiment was conducted in 2005 on Stagnic Gleysol soil where different organic amendments were applied, such as compost, pig manure, and sewage sludges from the sewage-treatment plants of Krzeszowice and Czernichów. The results were compared with mineral fertilizers and an untreated control. The amounts of all fertilizers were determined adequate to supply 110 kg N ha⁻¹. The pig manure and sewage sludges change the soil porosity in range of pores <50 μm in diameter. The application of these organic fertilizers decreases the volume of small pores (<0.005 μm) and increases porosity in the range 0.005-50 μm. This resulted in an increase in both available and productive water retention. The compost and mineral fertilizer application do not affect the air-water properties of Stagnic Gleysol.