Abstract: 【Objective】The application of coated slow/controlled release fertilizer is an important method for reducing nitrogen loss and increasing nitrogen use efficiency. A new type of organic-inorganic materials coated fertilizer has advantages of excellent release performance and environmentally friendly, etc. Studies on nitrogen volatilization characteristics of organic-inorganic materials coated fertilizer could provide scientific basis for the development and application of coated slow/controlled release fertilizers. 【Method】 In our study , the coated fertilizers were prepared by encapsulating urea granules with blend films of modified polyvinyl alcohol (PVA) and inorganic material including diatomaceous earth (Ag)，zeolite powder (Af), biochar (Ac), phosphate rock (Ap) and sulfur (As). A laboratory culture experiment was conducted to demonstrate the characteristics of ammonia volatilization and nitrogen oxide emissions from soil treated with various coated fertilizers through determining soil ammonia volatilization rate and nitrogen oxides emission rate in 60 days. A pot culture experiment was also carried out to study the effects of different coated fertilizer applications on growth and yield of rape.【Result】Ammonia volatilization began at the first day of incubation after fertilizer incorporating into soil. Moreover, Ammonia volatilization rate for different treatments reached maximum values within 10 days after incubation. The peak values for CK, Ag, Af, Ac, Ap and As were 1.132 mg·L^-1·d^-1, 0.373 mg·L^-1·d^-1, 0.508 mg·L^-1·d^-1, 0.696 mg·L^-1·d^-1, 0.347 mg·L^-1·d^-1, 0.304 mg·L^-1·d^-1, respectively. The peak values of soil ammonia volatilization treated with coated fertilizers appeared later than urea treatment, indicated that the blend film encapsulated urea granules could prolong urea dissolved time and subsequently slow urea dissolution rate through effectively preventing the external which could effectively prevent the external water from contacting urea. Generally, ammonia volatilization rate exhibited a steady trend after dramatic variation. The total ammonia volatilization for treatments of CK, Ag, Af, Ac, Ap and As were 104.0 mg, 88.2 mg, 93.4 mg, 95.6 mg, 81.9 mg, 79.4 mg respectively. The total ammonia volatilization from these five coated fertilizer treatments were 15 % (Ag), 10 % (Af), 8 % (Ac), 21 % (Ap) and 23 % (As) lower than that of urea treatment (CK). The emission characteristics of nitrogen oxide for different coated fertilizers were similar with ammonia volatilization. Compared with ammonia volatilization, the peaks of NOx emission obviously shifted rearward, which were observed between 6 and 23 days. The peak values of NOx emission for CK, Ag, Af, Ac, Ap and As were 0.092 mg·L^-1·d^-1, 0.033 mg·L^-1·d^-1, 0.039 mg·L^-1·d^-1, 0.051 mg·L^-1·d^-1, 0.027 mg·L^-1·d^-1, 0.022 mg·L^-1·d^-1, respectively. NOx emission accumulation for CK, Ag, Af, Ac, Ap and As were 15.8 mg, 11.1 mg, 12.4 mg, 13.2 mg, 10.3 mg, 8.5 mg, respectively. The overall nitrogen oxides emission from coated fertilizer treatment was lower than that of uncoated urea treatment. Ammonia volatilization from different treatments accounted for 80-90 % of nitrogen gaseous loss. The rape yield of coated fertilizer treatment was higher than that of CK. The yield increase for treatments were diatomaceous earth (Ag) 47%, zeolite powder (Af) 37%, biochar (Ac) 31%, phosphate rock (Ap) 52%, sulfur (As) 63%, respectively.【Conclusion】In our study, ammonia volatilization was the main form of nitrogen gaseous loss from soil treated with coated fertilizers, which mainly occurred in the first two weeks after fertilization. The organic-inorganic materials coated fertilizers could inhibit ammonia volatilization and nitrogen oxides emission from soil. Ultimately, these coated fertilizers increased rape yield.

Key words: coated fertilizer, ammonia volatilization, nitrogen oxides emission, rape yield