The application of nitrogen (N) fertilizer to increase crop yields has a significant influence on soil methane (CH4) and nitrous oxide (N2O) emission/uptake. A meta-analysis was carried out on the effect of N application on (i) CH4 emissions in rice paddies, (ii) CH4 uptake in upland fields and (iii) N2O emissions. The responses of CH4 emissions to N application in rice paddies were highly variable and overall no effects were found. CH4 emissions were stimulated at low N application rates (<100 kg N ha–1) but inhibited at high N rates (>200 kg N ha–1) as compared to no N fertilizer (control). The response of CH4 uptake to N application in upland fields was 15% lower than control, with a mean CH4 uptake factor of –0.001 kg CH4-C kg–1 N. The mean N2O emission factors were 1.00 and 0.94% for maize (Zea mays) and wheat (Triticum aestivum), respectively, but significantly lower for the rice (Oryza sativa) (0.51%). Compared with controls, N addition overall increased global warming potential of CH4 and N2O emissions by 78%. Our result revealed that response of CH4 emission to N input might depend on the CH4 concentration in rice paddy. The critical factors that affected CH4 uptake and N2O emission were N fertilizer application rate and the controls of CH4 uptake and N2O emission. The influences of application times, cropping systems and measurement frequency should all be considered when assessing CH4 and N2O emissions/uptake induced by N fertilizer.

Antibacterial effect of cinnamon oil combined with thyme or clove oil was studied in this paper. Agar dilution method wasused to determine the minimum inhibitory concentrations (MICs) of the essential oils (EOs) of cinnamon, thyme, and cloveoil against three Gram-positive bacteria (Bacillus subtilis, Bacillus cereus, and Staphylococcus aureus), and two Gramnegativebacteria (Escherichia coli and Salmonella typhimurium). The results showed that cinnamon was a promisingantibacterial substance with MIC ranged from 0.1 to 0.4 μL mL-1 for the five bacterial species. Agar dilution checkerboardmethod was used to test the combined antibacterial effect of cinnamon oil with thyme or clove oil. Combination ofcinnamon and thyme oil showed an additive effect against all selected bacteria, and combination of cinnamon and cloveoil displayed an additive effect against B. subtilis, B. cereus, S. aureus, and an indifferent effect against E. coli andS. typhimurium. Furthermore, gas chromatography-mass spectrometry (GC-MS) measurement was used to analyze thecomponents of the EOs, and the main components of cinnamon, thyme, and clove were cinnamaldehyde, thymol, carvacroland p-cymene, and eugenol, respectively.