METHANE MITIGATION IN FLOODED LOUISIANA RICE FIELDS

A field experiment was conducted to determine whether selected nitrifi cation inhibitors (encapsulated calcium carbide and dicyandiamide) and SO4-2-containing compounds [(NH4)2SO4 and Na2SO4] had mitigating effe cts on CH4 emissions from flooded rice. Microplots were established wi thin a rice bay drill-seeded with the Texmont rice cultivar and CH4 fl uxes were measured over the main rice cropping season. Methane emissio ns over the 77-day sampling period were approximately 230, 240, 260, 2 90, 310, and 360 kg CH4 ha-1 from the calcium carbide, Na2SO4-rate II, Na2SO4-rate I, (NH4)2SO4, dicyandiamide, and urea (control) treatment s, respectively. Reductions in CH4 evolution, compared to the control, ranged from 14 to 35%, depending on treatment. The selected inhibitor s and SO4-2-containing compounds appear to be effective in reducing th e CH4 emitted from flooded rice fields.