Nitrate leaching from intermittently flooded rice fields contributes to nitrate pollution in groundwater. In this
study, redox conditions and nitrate change in a newly flooded rice soil under the influence of oxidative iron
(Fe) and manganese (Mn) were investigated using flooded soil columns under moderate percolation
(4.2mmd1). The amendments of -Fe2O3 and -MnO2 powder (5 and 2.7 mg g1, respectively) delayed the
establishment of reducing conditions and lowered the rate of nitrate removal in the soil column, and
subsequently increased the percolation of soil indigenous nitrate (8.3 mg nitrogen [N] kg1) from 2.0% to
8.0%, and the percolation of externally amended nitrate (250 mgNkg1) from 11.0% to 26.0%. The pool of
oxidative iron-centered metal oxidants needs to be jointly considered with the availability of organic carbon
and hydrological conditions in evaluating redox conditions and nitrate change in intermittently flooded rice
soils.
Key words: redox potential, nitrate leaching, oxidative iron, alternative electron acceptor.