Contrasting effects of EDTA applications on the fluxes of methane and nitrous oxide emissions from straw-treated rice paddy soils.

Abstract

Submerged rice paddy soils are the major anthropogenic source of methane (CH4 ) emission to the atmosphere. Straw incorporation for sustaining soil organic C pool increases CH4 emission flux from rice paddy soils. Though the rate of nitrous oxide (N2 O) emission is much less than CH4 , the former has 298 times higher global warming potential (GWP) than equivalent quantity of carbon dioxide. The effect of chelating agents, such as EDTA, on N2 O emission and on GWP due to CH4 and N2 O emissions has not been evaluated before. The emission of CH4 gas from submerged soil may be mitigated by EDTA application; however, it also increases concentration of nitrate-N in soil, the precursor of N2 O gas formation under anaerobic condition. In this experiment, irrespective of straw application, EDTA-treated soils emitted less CH4 to the atmosphere than the corresponding control. Though N2 O emission was increased from soil due to EDTA applications, total GWP was at least 15% reduced in EDTA treated soils during rice cultivation. The plant growth and rice grain yield was not affected by EDTA application. EDTA application at 5.0 ppm might be used to reduce total global warming potential during rice cultivation. © 2016 Society of Chemical Industry.