Abstract: A field experiment was conducted to determine the effects of different novel synergistic urea on yield and nitrogen use efficiency of high-yielding rice variety （Mingzhu No. 2） on marine\|fluvigenic yellow loamy paddy soil in North Zhejiang in 2011. The results showed that rice grain yields in the treatments of common urea and seaweed urea were increased with increasing N rates， but for the treatments of humic acid urea and amino acid urea， the highest yields was obtained in the treatments of medium N rates （180 kg N·hm-2）. Total N uptake rates by rice aboveground followed the order: seaweed urea （253.5 kg N·hm-2）＞humic acid urea （242.1 kg N·hm-2）＞common urea （236.8 kg N·hm-2）＞amino acid urea （230.8 kg N·hm-2）. Total N uptake rates and N demand amounts per 100 kg rice grain increased with increasing N rates， while dry matter production efficiency， rice grain production efficiency， N harvest index， N use efficiency， and internal N use efficiency were decreased with increasing N rates. Rice grain yields were fairly correlated with N demand amounts per 100 kg rice grain， dry matter production efficiency， grain production efficiency， N use efficiency， internal N harvest index （P<0.05）. In this experiment condition， N fertilizer rate of 3 kinds of novel synergistic urea should be controlled at 180 kg N·hm-2， at which novel synergistic urea could obtain greater increased yield effect than common urea.

Key words: rice, novel synergistic urea, nitrogen fertilizer rate, yield, nitrogen use efficiency