Experimental design
We incubated isotopically enriched litter in soil ingrowth cores and
traced the fate of litter C and N into SOM over one growing season. Our
experimental design included 3 levels of root/hyphal ingrowth: root and
fungal ingrowth (root), root exclusion and fungal ingrowth (fungal), and
root and fungal exclusion (none) and 3 fertilization treatments: no
fertilization (control), high-level inorganic fertilization (high N), or
organic fertilization (organic). We randomly selected 5 plots from each
fertilization treatment from those which had successful rhizome
establishment during initial plot development. Within each plot, we
replicated each ingrowth core treatment twice, where we installed
ingrowth cores by 2 of the plot’s 25 plants (SI Fig. 3b ). This
resulted in a total of 90 experimental ingrowth cores (3 cores x 3
fertilization treatments x 5 plots x 2 locations/plot).