Both ingrowth treatments and fertilization affect litter C and N transformations, but there was no interaction between these factors.
Root ingrowth core treatments and fertilization treatments both altered litter C and N transfers between SOM pools, but the root effect did not depend on fertilization (SI Table 2, all p-values for ingrowth core treatment x fertilization treatment interactions are above 0.05). As such, subsequent data shown for each factor are aggregated over the other factor.