Abstract:Humic acid-urea is one of the novel inorganic-organic fertilizers. Different activation approaches to humic acids play important roles in the efficiency of humic acid-urea. Present study was conducted in cinnamon soil to identify the effects of different activation humic acid-urea treatments on wheat and maize yield, soil organic carbon with a field experiment and nitrogen mineralization with an incubation experiment. Results showed that fertilizer treatments increased the wheat and maize yields. Humic acid-urea treatment increased yield by 15%–28% and 8%–10% for wheat and maize than inorganic fertilizer treatment, and increased by 63%–81% and 55%–57% compared with the control treatment(CK), respectively. In detail the cooperation of sulfurization activation and ultrasonic treatment was better in increasing crop yield than direct mixture treatment and merely sulfurization activation treatment. There were significant differences in soil nutrients among the different fertilizer treatments. Soil NO3–-N and NH4+-N contents were in an order of U+HA1, U+HA3 > U+HA2 > Urea > CK. The direct mixture treatment decreased soil NH4+-N content compared with the other activation treatment for humic acid-urea. Fertilization treatments improved soil available phosphorus and available potassium contents, whereas the humic acid addition had no effect on soil available phosphorus and available potassium contents in comparison to inorganic treatment.Humic acid-urea treatment didn’t significantly influence soil organic carbon content, but enhanced soil organic carbon mineralizing rate and accumulative quantity, indeed the influences of the cooperation of sulfurization and ultrasonic activation treatment were more obvious among three treatments. There was significant positive correlation between soil organic carbon mineralization accumulative quantity and total crop yield, soil available nitrogen, potassium and phosphorus content. Compared with the control treatment, inorganic fertilizer treatment boosted soil organic nitrogen mineralization rate, but humic acid addition didn’t work. The rate of soil organic nitrogen mineralization was positively correlated with soil available phosphorus content. Humic acid-urea fertilizer should be recommended to improve soil fertility and productivity than inorganic fertilizer. The ideal dealing approach was the cooperation of sulphur activation and ultrasonic treatment for humic acid-urea. Humic acid-urea with the cooperation of sulphur activation and ultrasonic treatment is worth to popularize in fertilizer resource and market.