Effects of micro-molar H2O2 on inhibiting soil nitrification

Microcosm experiments were conducted to examine the effects of micro-molar hydrogen peroxide (H2O2) on soil nitrification in three scenarios: (a) without added fresh biomass and magnetite, (b) with added fresh biomass, and (c) with added magnetite. The results show that nitrification of the added ammonium was impeded in the presence of H2O2 at a concentration range of 20-50 μM probably as a result of weakened activities of ammonia-oxidizing microbes due to oxidative stress caused by H2O2 and possibly hydroxyl radical (OH). Application of grass clippings or magnetite enhanced the effects of H2O2 on inhibiting soil nitrification. The research findings obtained from this study have implications for understanding the complication of soil nitrification by rainwater-borne H2O2 during flood events and developing cost-effective and environmentally friendly techniques for nitrification inhibition in fertilized soils.