Effect of Nutrient Management on Nitrogen Utilization of Rice Panicle Nitrogen Fertilizer Applied to Rice and Succeeding Wheat Crops in a Rice-Wheat Rotation System.

To investigate the absorption and utilization of nitrogen applied to the panicle in rice and the effect of residual nitrogen on the utilization of nitrogen in the succeeding wheat crop in the rotation system. A field experiment was combined with a mini-plot experiment with 15N labelled urea. Results: (1) Compare to conventional fertilizer management (F), the optimized fertilizer management (S1&S2) reduced the amount of nitrogen applications, whereas the rice and wheat yield did not decrease, and nitrogen use efficiency was improved. (2) Residual rice panicle fertilizer nitrogen in the 0-20 cm soil was 4.7%-10.7%; residual rice panicle fertilizer nitrogen absorbed by the wheat during the period from jointing to heading accounted for 37.0%-51.1%. (3) The sum of the ratio of nitrogen absorption from the rice panicle fertilizer applied to the crops (rice and wheat) and ratio of soil residue nitrogen in the wheat field were ordered S2 > S1 > F. Conclusions: The optimized fertilization management reduced the loss of the rice nitrogen in the rice- wheat rotation system through improved recycling of rice panicle nitrogen applied in the crop-soil system.