Methane efflux from rice-based cropping systems under humid tropical conditions of Eastern India

Abstract

Tropical rice paddy is considered to be one of the major anthropogenic source of atmospheric methane (CH₄). In a field study spread over the dry and wet seasons of a calendar year, the CH₄ emission from upland (oilseed and pulse) crops in the dry season and a succeeding lowland rice (Oryza sativa L.) crop in the wet season was compared with rice-rice rotation in both seasons under flooded conditions. Cumulative CH₄ flux from the upland crop followed by lowland rice crop was low (12.52-13.09 g CH₄ m²) compared to that of the rice-rice rotation (39.96 g CH₄ m²). What was particularly interesting is that the seasonal mean CH₄ emission from the lowland rice in wet season preceded by an upland crop in dry season was low when compared to that of lowland rice in wet season preceding a dry season flooded rice. Results indicate that the cumulative CH₄ emission from tropical rice ecosystem can be lowered by growing suitable upland crops to reduce the period that rice paddies are submerged during an annual cropping cycle.