Field investigation of carbon dioxide (CO2) fluxes and organic carbon from a conserved paddy field of North–East India

Abstract

This study investigates the effects of conserved tills on the fluxes of carbon dioxide (CO2) and soil organic carbon (SOC) from a rain–fed–paddy plot in Assam (North–eastern state of India). Two paddy plots identical in soil properties, developed to cultivate rice (Sali, grown in low–lying areas of Assam), were adjacent to each other to follow a conventional agricultural practice in one and conservation in the other. Two chambers (1 m×0.6 m×0.4 m) were placed in both the plots to collect runoff for analyzing CO2 concentrations. The results of the both practices have been inter–compared. For conservation plot, the SOC was high in the range from 3.17+0.01 kg m−2 to 20.42+0.56 kg m−2 and the CO2 emission was less, i.e. 97.30+7.11 mg m−2 h--1 as compared to 189.65+4.37 mg m−2 h--1 of the conventional plot. Low tillage practiced for the conservation plot facilitated higher porosity (50.11+8.40% to 88.87+3.59%) and greater water retention (47.47+1.15% to 101.37+1.63%) in the soil. The results indicate that more tillage exposed the soil to atmospheric oxygen more, which leads to excess mineralization of organic carbon and emissions of CO2 as in the conventional plot. Keywords: Paddy, SOC, CO2, Emission, Tillage