A pot experiment coupled with short term mineralization incubation were conducted to explore characteristics of residual, mineralization and crop uptake of the ¹⁵N-labeled N fertilizer applied alone and/or together with crop straw in the soils collected from three different treatments of a 19-year fertilizer experiment, i.e. treatment No-F (no fertilization), treatment NPK (long-term NPK fertilization) and treatment MNPK (long-term NPK fertilization plus organic manure). The pot experiment was designed to have two treatments, i.e., treatment +N (100 mg kg^-1 urea-¹⁵N), and treatment +1/2N+1/2S (50 mg kg^-1 urea-¹⁵N + corn stalk equivalent to 50 mg kg^-1N). Fertilizers were added to the pots separately for the first cropping of wheat in 2009. After the first cropping of wheat was harvest, 82.6% ~ 95.1% of the residual fertilizer N in all the three soils under treatment +1/2N+1/2S and NPK soil and MNPK soil under treatment +N were in organic form; and 47.7% of the residual fertilizer N in the No-F soil under treatment +N was in mineral form. After 28 days of incubation for mineralization, the net N mineralization in MNPK soil increased significantly, by 39% ~ 49% over that in NPK soil. In NPK and MNPK soils, 1.23 to 1.90 mg kg^-1 of the residual fertilizer N was mineralized, accounting for 2.78% ~ 5.53% of the total residual fertilizer N in the soils. The net mineralization rate of residual fertilizer N in NPK and MNPK soils was significantly higher than that in No-F soil. Compared to treatment +N, treatment +1/2N+1/2S significantly increased net N mineralization rate in the three soils. However, the two treatments did not affect much the mineralization rate of residual fertilizer N in NPK and MNPK soils. In No-F soil under treatment+N, the residual fertilizer N use efficiency (RNUE) reached 20% in the No-F soilsignificantly higher than that (9%)in NPK and(12%) MNPK soils (p< 0.05). The RNUE in MNPK soil was significantly higher than that in NPK soil regardless of N treatment (i.e., +N, or +1/2N+1/2S). N uptake by the second crop of wheat during the vegetative growing period was found to be significantly and positively related to net soil N mineralization rate during the short incubation period, while no significant correlation was observed between residual fertilizer N mineralization rate and amount of residual fertilizer N absorbed by the second cropping of wheat. To sum up, long-term combined application of organic manure and chemical fertilizer can increase the mineralization rate of residual fertilizer N, and hence improve its bioavailability.