Objective  The application effects of stability urea adding different biochemical inhibitors and humic acids were carried on rice planted in black soil, in order to provide a theoretical basis for the development of a new generation of high efficiency and stability urea for rice planted in black soils.

  Method  In the pot experiment, blank (CK) and urea (N) were set as controls, through the determination nitrogen transformation characteristics of paddy soil, rice physiological indices, yield and nitrogen fertilizer use efficiencies, to investigate the differences in nitrogen supply stability of 7 kinds of stability urea made from humic acids (HA), N-butyl thiophosphate-triamine (NBPT), 3,4-Dimethylpyrazole phosphate (DMPP), 2-chloro-6-trimethyl-pyridine (CP) and humic acids with 3 biochemical inhibitors, respectively.

  Result  ① Urea (N) was set as controls, adding humic acids, NBPT, DMPP and CP could increase rice yield, N uptake and nitrogen use efficiency. ② Compared with the application of NBPT alone, the addition of humic acids could effectively inhibit soil nitrification, plant height, tiller number and chlorophyll contents of rice were increased by 1.84%, 13.38% and 2.80%, but yield, leaf area, nitrogen uptake, NUE and NPFP of rice were decreased. ③ Compared with the application of DMPP alone, the addition of humic acids could increase plant height, tiller number and chlorophyll contents of rice by 3.04%, 5.20% and 3.71%, respectively. And it also could significantly decrease nitrification inhibition rate, rice yield, nitrogen uptake, NUE and NPFP (P < 0.05). ④ Compared with the application of CP alone, the addition of humic acids increased soil available nitrogen content, plant height, tiller number, chlorophyll contents and total biomass of rice, significantly increased grain yield, nitrogen uptake, NUE and NPFP（P < 0.05）.

  Conclusion  Adding humic acids and CP to urea to make a new type of stability urea for rice cultivation in the black soil area of northeast China is beneficial to the increase of crop yield and the improvement of nitrogen use efficiency.