Effect of organic and inorganic fertilizers and rice straw on carbon sequestration and soil fertility under a rice–rice cropping pattern

ABSTRACTRice–fallow–rice, the dominant cropping system in Bangladesh, has received little attention regarding soil organic carbon (SOC) changes through organic amendments. Understanding the contributions of organic amendments in C sequestration is important for carbon budgeting. This study determined the effect of organic amendments on CO2 emission to the atmosphere and C sequestration in soil. A series of field experiments in five consecutive rice seasons were conducted during 2010–2012 at the research farm of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Bangladesh, using five treatments – control, cow dung (CD), poultry manure (PM), rice straw (RS) and soil test-based fertilizer (STB). The carbon application rate from CD, PM and RS was 2 t C ha−1 season−1. Carbon dioxide production from rice fields was measured through NaOH absorption followed by HCl titration. The difference in the amount of cumulative CO2 evolution and SOC accretion between the control and organic treatments gave apparen...