Nitrous oxide production from strongly acid tea field soils

Abstract

Nitrous oxide (N2O) production from acid (pH 3.60) tea field soil under aerobic conditions was studied in a laboratory experiment. A large amount of N2O (53 μ N g−1 soil 14 d−1) was produced under aerobic conditions when ammonium and nitrate were added to the soil. It was assumed that the high N2O production was an inherent property of the soil because soil pre-treatments (e.g., air-drying) did not affect it. A 15N tracer study indicated that N 2 was not produced from the acid tea field soil. N2O was produced during biological reactions, and the contribution of N2O production during chemical reactions to the whole N2O production was negligible. Nitrapyrin (2-chloro-6-(trichloromethyl)- pyridine) and acetylene (0.1 Pa), which are selective nitrification inhibitors, slightly reduced N2O production. These results indicate that denitrification is the main process of N2O production in acid tea field soil. The levels of N2O production from four tea field soils collected from the same area were compared. The results showed that a large amount of N2O is likely to be produced from a soil with a pH value below about 3.60 and to which a large amount of nitrogen fertilizer (more than 1,000 kg N ha1−1 y1−1) had been added. © 2000 Taylor 0026; Francis Group.