The dynamics of various nitrogen forms in soil and characteristics of nitrogen utilization under application of urea and different organic materials were studied with pot experiment. The results showed that crop nitrogen uptake decreased when urea(U) applied with high C/N ratio of wheat straw(WS) and increased when urea applied with low C/N ratio of poultry manure(PM). There were no significant difference in crop biomass among U, U+WS, U+PM treatments. Urea hydrolysis and nitrification completed wi...