Daily production of large quantities of organic solid wastes creates serious disposal problems, environmental pollution and possible health risks. Solid wastes may be converted into useful products by composting and vermicomposting. The nitrogen content of these organic fertilizers is mostly in organic form, therefore, understanding the effect of vermicompost on N mineralization, nitrification and enzyme activity in soils is crucial for a better assessment of N fertilizer requirements in order to increase plant yield. The objective of this study was to identify the effect of cow manure and sugarcane filtercake vermicomposts on net N mineralization, enzyme activity and wheat growth and N uptake. Three soil samples (Shervedan, Zayanderood and Langrood) were air-dried and passed through a 2-mm sieve. Four organic fertilizers (cow manure, sugarcane filtercake, vermicompost of cow manure and sugarcane filtercake) were air-dried and passed through a 4-mm sieve. A series of experiments were conducted in two phases. First organic fertilizers and urea were mixed with soil to provide 100 kg N ha -1 and biological properties such as C mineralization, net N mineralization, nitrification, anaerobic index of biological available nitrogen (N ava ), urease and L-glutaminase activites were evaluated. Then a pot culture study evaluated the effect of vermicomposts of cow manure and sugarcane filtercake on wheat growth and its N uptake. Results revealed that N mineralization and N ava were not increase significantly by vermicomposting. But this increase for nitrification was significant. The effect of vermicomposts on enzymes activity were related to soil types and for wheat yield and N uptake were related to time of harvesting. The short-run (24 hr) C mineralization showed to be an index to estimate net N mineralization
