| At present, more attention is paid to the global warming by scientists all over the world. It is recognized that the main reason of global warming is the increasing concentration of greenhouse gases (GHGs), including CO2, CH4, N2O and chlorofluorocarbons (CFCS) et al. CH4, and N2O is two important GHGs next to CO2, which contribution is 20% and 5%7% of total contributions of all GHGs. The mole warming potential of CH4 and N2O are 56 times and 280 times to that of CO2, respectively. They also participate in some chemical reaction in atmosphere. Therefore, the increase of the N2O and CH4 concentration in atmosphere is stressed by the public, scientists and government.With the increasing of population, the demand of food is increasing. The application of inorganic fertilizers, especially nitrogen fertilizer, is the important means for enhancing the crop yield. However, some environmental problem arised, such as ammonia volatilization, N2O emission, NO-3 leaching. It is reported that the application of fertilizer is the most important direct source of N2O and the amount of N2O from the fertilizer is about 28% of anthropogenic direct N2O source.At present, compared to the developed contrary, the availability rate of nitrogen in China is lower. Therefore, to study and develop the new fertilizers, such as the modifed nitrogen fertilizers, is overwhelming for enchancing the availiability rate of nitrogen and decreasing the environmental pollution. There are three types of modified fertilizers: physical type, chemical type and biochemical type. The physically modified fertilizers change the physical characters which make it release slowly and get a higher availability rate; There is linkage of fertilizer to some chemical materials in the chemically modified fertilizers; with addition of some microbial inhibitor or enzyme inhibitor, the hydrolysis of nitrogen fertilizer is controlled in the biochemically modified fertilizers.In this paper, a physically modified fertilizer, Meister made by Chissco fertilizer Co., Japan, which coated with resin, and several biochemically modified fertilizers with addition of nitrification inhibitor and/or urease inhibitor including NI (urea plus nitrification inhibitor), NUI (urea plus nitrification inhibitor and urea inhibitor), UI-1 (urea plus urease inhibitor 1), UI-2 (urea plus urease inhibitor 2) and FL (urea plus 1.0%DCD and 0.3%HQ) were selected as the tested fertilizers. By the incubation experiments, the mitigation effect of these modified fertilizers on the N2O and CH4 emissions from upland soil and paddy soil were studied. Furthermore, the N2O fluxes from the maize upland and CH4 and N2O flux from paddy soil with application of different modified fertilizers were observed by the static closed chamber technique. The preliminary investigation on microbiological mechanism in mitigation of CH4 emission from paddy soil, cooperated with the application of urea with nitrification inhibitors addition, was conducted by incubation experiments in this study.The incubation tests were conducted with upland soil and flooded paddy soil under different soil water conditions. The mitigation effect of the tested fertilizers on the emission of N2O and CH4 were studied. The results showed that under 75% and 90% water holding capacity, Meister improved the N2O emission during the entire incubation period, Compared to the normal Urea, Meister increste the N2O by 123.6% and 97.8%, NI, NUI, FL, SUDT, UI-1 and UI-2 mitigated the N2O by 52.7% and 38.7%, 32.8% and 51.2%, 40.0% and 53.7%, 24.3% and 56.8%, 33.2% and 37.8%, 35.1 and 36.5% respectively. UI-1 and UI-2 released more N2O during the early period of incubation. Under flooded, compared to the normal urea, Meister, NI, NUI, FL mitigated the N2O by 62.1%, 35.5%, 37.5%, 59%o The effect of CH4 mitigation from paddy soil by these modificed ureaes is insignificant under flooded condition during the incubation.By the observation in situ of N2O flux from maize field, it is found that NI, NUI, Meister and FL all decreased the N2O emission. Compared to the nomal urea, NI, NUI and FL mitigated the N2O emission by 63.8%, 57.42%, 66.87%, Meister reduced N2O emission by only 0.71%. These results suggested that the biochemically modified fertilizers could reduce significantly the N2O emission in upland. The reduction of N2O emission by coated urea was insignificant. At the same time, the temperature and the soil water contents were measured when the gas samples was collected. The results showed a positive correlation between the temperature in the different soil depth and N2O emission of all treatments (exception of NUI). The soil water content correlated positively with the N2O flux in the control treatment.In the rice paddy field, the effect of NI, NUI, Meister, and SU on CH4 and N2O emission in situ were studied. The results showed, compared to the control (CK), all the urea reduced the CH4 emission. During the rice growing period, NI mitigated significantly the CH4 emission. Compared to the urea, NI reduced the CH4 emission by 35.6%. At the same time, irrigation mode was an important controlling factor for CH4 emission in rice field. The different between CH4 emissions from two rice cultivars tested, bothLiaoKai 77 and 294, is insignificant.It is found that NI can mitigate the CH4 emission compare to the normal urea. In order to discuss the phenomena, the incubation test was conducted. Under different water contents, the effect of NI and NUI in the different concentrations of urea on CH4 oxidation and the amount of methane-oxidation bacteria were studied. The results indicated, low concentration of NI stimulated the methane oxidation in the early period of incubation under 25% (w/w) water content. Under flooded condition, NUI stimulated methane oxidation in the fourth days, compared to the control. When high concentration of NI and NUI were applied, under the 19% water content, NUI stimulated the methane oxidation in the second day, NI and NUI inhibited the methane oxidation in the fourth day; under 25% (w/w) water content, NUI and NI didn't influence the methane oxidation in the...
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