id	keyword
hungeobull-1257	soil
hungeobull-1257	isotope
hungeobull-1257	carbon
hungeobull-1257	13c
hungeobull-1257	som
hungeobull-1257	et al
hungeobull-1257	co2
hungeobull-1257	turnover
hungeobull-1257	abundance
hungeobull-1257	fractionation
hungeobull-1257	δ13c
hungeobull-1257	vegetation
hungeobull-1257	plant
hungeobull-1257	matter
hungeobull-1257	kuzyakov
hungeobull-1257	science