Global warming might accelerate the decomposition of soil organic carbon (SOC) stock,due to more highly increased microbial activity than net primary production (NPP). Thedepletion of SOC stock can deteriorate soil quality and worsen climate change, and therefore,higher amounts and more recalcitrant types of organic amendment applications might berequired under future climate conditions. To investigate the feasibility of organic amendmentsself-produced inner rice cropping boundary to sustain SOC stock under global warming, covercrops during the fallow season and rice during the cropping were cultivated under the presentand future climate (2℃ and 200 ppm CO2 elevation over the ambient) conditions. Cover cropbiomass and rice straw were incorporated by fresh and biochar (pyrolysis at 400℃ for 2 hours)types. Annual SOC stock changes were estimated using net ecosystem C budget (NECB)which implies the difference between C input and output. Under the present climate condition,no organic amendment (NPK) decreased SOC stock by 0.6 Mg C ha-1 year-1, but fresh biomassapplication significantly increased SOC stock by 1.5 Mg C ha-1 year-1. In comparison, biocharapplication slightly increased SOC stock by 0.1 Mg C ha-1 year-1, due to low biochar yield (25-40% of fresh biomass) and low NPP. Global warming more highly decreased annual SOCstock by 122-176% over the present under the same amendments. Under global warming,biochar application was more effective than fresh biomass in reducing SOC loss but did notcreate positive NECB. In conclusion, only the utilization of biomass self-produced inner ricecropping boundary may not be enough to increase SOC stock under global warming conditions.Therefore, more application of biochar, a recalcitrant organic amendment, might be essential,via increasing biomass productivity by fertilizer and water management.