[Effects of organic and inorganic fertilizers on emission and sources of NO in vegetable soils].

To clarify the microbial pathway of the NO production and consumption under different fertilizers and provide theoretical basis for the reduction of NO emission and rational management of fertilization in vegetable soils, we examined dynamics of NO flux and isotope signatures under different fertilizer treatments in the vegetable soils of Beijing, by setting up four treatments (organic-acetylene, organic-nonacetylene, inorganic-acetylene, inorganic-nonacetylene) and using the stable isotope technique of natural NO abundance. The results showed that the cumulative NO emission from organic-acetylene group, organic-nonacetylene group, inorganic-acetylene group and inorganic-nonacetylene group was (374±37), (283±34), (458±36), (355±41) g·m in cabbage growing season, respectively. NO fluxes were significantly lower in treatments with organic fertilizer than those with inorganic fertilizer and significantly higher in acetylene group than nonacetylene group. The degree of NO reduction were similar in both fertilizer treatments, and higher nitrification was found in inorganic fertilizer than organic fertilizer treatments. Acetylene only inhibited partial nitrification and partial NO reduction at the peak of NO emission. When the emission was reduced, NO reduction could be completely suppressed. Therefore, the inorganic fertilizer might trigger nitrification and promote higher NO emission. The high concentration of NO could withstand that acetylene to inhibite NO reduction. Hence, using organic fertilizers instead of some inorganic ones could effectively reduce NO emission in vegetable soils of Beijing. The NO concentration threshold should be considered when we identify NO source by acetylene inhibition method.