Nitrous Oxide Production and Consumption in Subtropical Peatlands.

Peatlands are a potential source of nitrous oxide (N₂O) to the atmosphere, and have significant impacts on global warming and stratosphere depletion. Large areas of peatlands in south Florida have been converted into agricultural lands, currently known as the Everglades Agricultural Area (EAA). Objectives of this study were to: (1) determine N₂O production and consumption potentials in soils under different land uses; (2) examine the limiting factor(s) of N₂O cycling; and (3) investigate the effects of soil biogeochemical properties on N₂O production and consumption.

A batch incubation study was conducted on soils (0-10 cm) collected from four land uses in the EAA, Florida: sugarcane, vegetables, turfgrass, and uncultivated soils. During a 116-h incubation, total N₂O production was significantly higher in soils from turfgrass (85.4 ± 13.9 mg kg^-1) and uncultivated (68.3 ± 3.4 mg kg^-1) soils, compared to sugarcane (20.3 ± 5.1 mg kg^-1) and vegetable (29.9 ± 0.9 mg kg^-1) soils, which were the most intensively cultivated and managed land uses. Total N₂O consumption was highest in turfgrass soils (72.3 ± 10.3 mg kg^-1), which was 2 times higher than for uncultivated soils, and about 3-fold greater than sugarcane and vegetable soils. Sugarcane soils had the lowest net N₂O production (1.4 ± 0.3 mg kg^-1) of all land uses, while the highest net N₂O production (31.5 ± 3.4 mg kg^-1) was observed in uncultivated soils due to a low N₂O consumption/production ratio (53%). Nitrous oxide production and consumption were limited by NO₃^- in sugarcane soils while were limited by labile organic C for other land uses of these peatlands.