Effect of Soil Oxidants KNO₃, MnO₂, and Air on Methane Production in Flooded Rice Soil Suspension

Abstract

To determine effective means to reduce methane (CH₄) production from flooded rice soil, laboratory measurements were made on methane (CH₄) formation in a Crowley silt loam as affected by the addition of potassium nitrate (KNO₃), manganese dioxide (MnO₂), and air (O₂) under flooded conditions. In the experiment, oxidants were added to the soil prior to flooding at the rate of 300 and 1000 ppm O₂ equivalent. Methane production was measured over a 32 d incubation period. Potassium nitrate added at rates of 300 and 1000 ppm O₂ equivalent reduced CH₄ production by 100% and MnO_{_2}, at 300 and 1000 ppm O₂ equivalent, significantly decreased CH₄ formation approximately 20% and 98-99% over the 32 d period, respectively compared to controls. Air addition did not significantly affect CH₄ formation.