RESUMEN
Farmyard manure [C: N= 24], town refuse compost [C: N=36] or sewage sludge [C: N=8] was added to alluvial [Clay] and calcareous [clay loam] soil at the rate of 2% W./W. To study their effect on the densities of fungi and aerobic cellulose decomposers in soil and the changes in the soil carbon: nitrogen ratio. The numbers of the fungal colonies appearing on the count plates showed lower densities in the treated samples than the control of alluvial soil and the lowest numbers were observed in the sewage sludge treatment. This was attributed to the competition between the bacterial and fungal population. However, the counts of fungi in calcareous soil treated with organic manures were remarkably higher than those in the control treatment. The counts of aerobic cellulose decomposers were enhanced by the application of organic manures to both tested soils. The C: N ratio of the soils treated with sewage sludge showed the highest values followed by farmyard manure and town refuse compost which showed also higher values than control