Nitrous oxide dynamics during denitrification along a hydrological gradient of subtropical grasslands |
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| Authors: | Jing Hu Kanika S Inglett Alan L Wright Mark W Clark K Ramesh Reddy |
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| Institution: | 1. Soil and Water Sciences Department, University of Florida-IFAS, Gainesville, FL, USA;2. Indian River Research & Education Center, University of Florida-IFAS, Fort Pierce, FL, USA |
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| Abstract: | Nitrous oxide (N2O) dynamics during denitrification, including N2O production and reduction, particularly as related to soil depth, are poorly understood. The objective of this study was to investigate the rates of N2O production and reduction processes at various soil depths along a hydrological gradient in grazed subtropical grasslands. A batch incubation study was conducted on soils collected along a hydrological gradient representing isolated wetland (Center), transient edge (Edge) and pasture upland (Upland) in south-central Florida. Significantly different N2O production and reduction rates between hydrological zones were observed for surface soils (0–10 cm) under ambient conditions, with average N2O production rates of 0.368, 0.178 and 0.003 N2O-N kg?1 dry soil h?1 for Center, Edge and Upland, respectively, and average N2O reduction rates of 0.063, 0.132 and 0.002 N2O-N kg?1 dry soil h?1. Nitrous oxide production and reduction in subsurface soils maintained low rates and showed small variations between depths and hydrological zones. Our results suggest that N2O dynamics were affected by depth, mainly through labile organic carbon (C) and microbial biomass C, being influenced by hydrological zone primarily through soil NO3- content. The spatial distribution of N2O fluxes from denitrification along the hydrological gradient is likely attributed to the differences in N2O production and reduction in surface soils. |
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| Keywords: | denitrification greenhouse gas hydrology labile organic carbon nitrate soil depth wetland |
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