[Use efficiency and fate of fertilizer N in tomato field of Nanjing suburb].
Field plot and micro-plot experiments were conducted to investigate the use efficiency (UE) , fate, and loss of chemical fertilizer N in tomato field of Nanjing suburb. The results showed that the application of chemical fertilizer N did not show any benefit to the tomato yield, due to the adequate N supply from native soil and organic manure amendment. The UE of fertilizer N calculated by difference method ranged from 14.5% to 22.5%. In micro-plot experiment, 16.6% - 28.8% of applied urea 15N was recovered by the plant, and 34. 2% - 46.0% of it was lost. Applying fertilizer N increased the nitrate content in 0-100 cm soil layer, and 10% - 10.2% of urea 15N was leached to the depth below 40 cm at harvest time. N application increased the denitrification loss and N2O emission significantly, which occupied 5.50% - 6.01 % and 2. 62% - 4. 92% of the applied N, respectively. No ammonia volatilization was detected during the whole growth season. Reducing N application rate or applying coated urea could decrease the environmental risks of N application in vegetable fields, especially the risks from nitrate leaching and nitrification-denitrification loss.