Abstract:In order to reveal the uptake and utilization of nitrogen fertilizer at different stages in rice under water and biochar management, the method of combining field plot experiment with micro-area was used, and the 15N tracer technique was used to mark the application of basal fertilizer, tiller fertilizer and panicle fertilizer respectively. Taking conventional flooding irrigation as a comparison, the uptake, utilization, accumulation and transportation of basal, tiller and panicle fertilizer in rice under different water and biochar managements and the distribution of nitrogen fertilizer applied at different stages of rice maturity in different organs under two different irrigation modes were studied. The results showed that reasonable water and biochar management could significantly increase the total nitrogen accumulation, nitrogen uptake and utilization efficiency and yield of aboveground parts of rice at maturity stage. The contribution rate of fertilizer to total nitrogen accumulation under different water and biochar managements was about 17.81%~20.60%. There was no significant difference between the two irrigation modes (P>0.05). The uptake and utilization rates of basal fertilizer, tiller fertilizer and panicle fertilizer in rice were 15.55%~23.31%, 31.68%~44.91%, 48.82%~71.18%, respectively. The application of appropriate amount of biochar could significantly improve the uptake and utilization rates of basal tiller, tiller and panicle fertilizer. The uptake and utilization rates of tiller fertilizer and panicle fertilizer under dry-wet-shallow irrigation mode were better than those under conventional flooding irrigation except basal fertilizer. The uptake and utilization rates of tillering and panicle fertilizers were positively correlated with the total nitrogen uptake and utilization rates of fertilizers (P<0.01), and the contribution rate of nitrogen transport of basal, tiller and panicle fertilizer to grain was positively correlated with the corresponding uptake and utilization rates (P<0.01). Reasonable water and biochar management can improve the contribution rate of nitrogen transport to grain and the utilization rate of nitrogen absorption, and reduce the residue of nitrogen fertilizer in soil. The results can provide theoretical basis and technical support for the application of water and biochar management model in paddy field in cold black soil region.
