Effect of nitrogen management during the panicle stage in rice on the nitrogen utilization of rice and succeeding wheat crops

•The fate of fertilizer applied at the panical stage in rice evaluated.•Postponing nitrogen application reduced the losses of panicle applied fertilizer.•Residual fertilizer had insignificant effects on the nitrogen utilization of wheat.

Background and aimsThe main objectives of this paper were to investigate the absorption and utilization of nitrogen applied at the panicle stage in rice for promoting and protecting spikelet and the effect of residual nitrogen on the utilization of nitrogen in the succeeding wheat crop in the rotation system.MethodsA field experiment was combined with a mini-plot experiment with 15N labelled urea applied at the panicle stage in rice. The experiments included three nutrient management treatments: F, S1 and S2. 126 kg N ha−1, 120 kg N ha−1, 72 kg N ha−1 labeled with 30 atom% excess 15N were applied in rice, respectively.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) At rice harvest, 4.7–10.7% of the fertilizer 15N was found in the 0–20 cm profile. The fertilizer 15N absorbed by the wheat during the period from jointing to heading accounted for 37.0%-51.1% of the total 15N absorbed. (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.ConclusionThe 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.