Effects of organic and inorganic fertilizers on emission and sources of N2O in vegetable soils.

Abstract

To clarify the microbial pathway of the N2O production and consumption under different fertilizers and provide theoretical basis for the reduction of N2O emission and rational management of fertilization in vegetable soils, we examined dynamics of N2O 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 N2O abundance. The results showed that the cumulative N2O 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-2 in cabbage growing season, respectively. N2O 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 N2O 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 N2O reduction at the peak of N2O emission. When the emission was reduced, N2O reduction could be completely suppressed. Therefore, the inorganic fertilizer might trigger nitrification and promote higher N2O emission. The high concentration of N2O could withstand that acetylene to inhibite N2O reduction. Hence, using organic fertilizers instead of some inorganic ones could effectively reduce N2O emission in vegetable soils of Beijing. The N2O concentration threshold should be considered when we identify N2O source by acetylene inhibition method.