matter, a phenomenon called priming. However, priming is difficult to predict, making its
relationship with C input elusive. To assess this relationship, we added 13 C-glucose at five
levels (8 to 1606 μg C g− 1 week− 1) to the soil from four different ecosystems for seven
weeks. We observed a positive linear relationship between C input and priming in all soils:
priming increased from negative or no priming at low C input to strong positive priming at …