Effect of residual biomass burning on CO2 flux at a paddy field in Japan

Paddy field is one of the most important ecosystem in monsoon Asia, and takes a great important role in CO₂ uptake. Carbon budget in agricultural fields is largely influenced by some artificial managements. After the harvest of crops, residual biomass is burned on fields, brought out from fields, or left and plowed into paddy soils. If the open burning is conducted on fields, one part of biomass carbon would be emitted to atmosphere as CO₂, and the other part would be plowed into soils.

In this study, an experimental paddy field was divided into two areas to investigate what impact is brought on the annual CO₂ flux by the difference of disposal management of residual biomass after the harvest. At the one area, residual biomass was burned and plowed into soils after the harvest in late November 2011, 2012, and 2013. At the other area, residue was not burned and plowed into soils as usual. From three-years average of sampling surveys, carbon content of residue plowed into soils after the harvest was estimated 293±1 and 220±36 g C m^-2 at no-burned and burned area, respectively. Continuous eddy-covariance measurements of CO₂ fluxes at each area were conducted for three years. A little bit of difference in CO₂ flux between two areas was shown during rice season.