Influence of parent material and land use on abiotic N2O production following NH2OH and NO2− addition

Abiotic pathways, closely linked to soil physicochemical characteristics shaped by parent material and land management practice, may significantly contribute to nitrous oxide (N₂O) emissions. However, the mechanisms by which parent materials and land use types influence abiotic N₂O production from hydroxylamine (NH₂OH) and nitrite (NO₂⁻) remain unclear. This study analyzed fifteen acidic soils representing three parent materials and five land use categories. Our results indicated that while land use had minimal effect, parent material did show significant influence on abiotic N₂O production, particularly noticeable after NH₂OH application (P < 0.05). Soils derived from Quaternary red clay exhibited the highest abiotic N₂O production (2.55 μg N₂O-N g⁻¹ soil), approximately fivefold greater than granite-derived soils. This increase correlated with the higher manganese (Mn) content in Quaternary red clay soils, which enhanced abiotic N₂O production through NH₂OH decomposition. Additionally, the conversion ratios of NH₂OH to N₂O were substantially different among the soil parent materials, varying from 56.6 % in Quaternary red clay to 12.7 % in granite and 40.8 % in late Pleistocene sediment. The isotopic site preference (SP) values of N₂O were within the expected ranges that typify both ammonia oxidation and chemodenitrification processes, with NH₂OH and NO₂⁻ addition yielding SP values of 25–30 ‰ and around 20 ‰, respectively. These findings underscore the pivotal role of parent material in regulating abiotic N₂O production, particularly through NH₂OH decomposition, and highlight the importance of soil properties in mediating abiotic N₂O emissions.