Emission and Sequestration of Carbon in Soil with Crop Residue Incorporation

Abstract

The decomposition rate of incorporated crop residues and its implications on CO2 emission, carbon mineralization, carbon density and carbon sequestration in agricultural lands were studied during the period March to June, 2009 and 2010 under field condition. The amount of CO2 evolved during decomposition of various crop residues varied depending on C:N ratio theirin. The rate of CO2 emission was highest at 30 days of incorporation in horse gram residue, at 45 days for sesamum, niger, toria and buckwheat residues while rice and wheat residue showed maximum CO2 evolution at 60 days of incorporation and gradually declined subsequently up to 90 days irrespective of all crop residues. The percentage of carbon oxidized was maximum with rice residue (32.8%) followed by wheat (27.7%), sesamum (26.0%), niger (20.0%), toria (19.8%), buckwheat (17.9%) and horse gram (16.8%) residues. Horse gram residue increased carbon density by 31.2% over control. Maximum carbon sequestered (1057 g m-2) was found in case of horse gram residue followed by buckwheat over control. The maximum correlation co-efficient between CO2 emission and days of incorporation was found with sesamum residue (r = 0.972), rainfall with buckwheat(r = 0.826), maximum atmospheric temperature in rice (r = 0.871) and soil temperature with toria (r = 0.975) residue.