Substrate spatial heterogeneity reduces soil microbial activity

Soil heterogeneity influences microbial access to substrates and creates habitats varying in substrate concentrations, thus leading local variations carbon (C) dynamics. Based on theoretical considerations, we expected that higher would decrease activity. To test this hypothesis, modified spatial using 3D-printed cylinders with four compartments (either preventing or allowing diffusion between compartments). The same total amount of glucose (1.5 mg C per cylinder) was added either one compartment (highest concentration, 2.0 g?1 soil, highest heterogeneity), two (medium 1.0 intermediate (lowest 0.5 equivalent homogeneous conditions). Thus, experimentally created a gradient heterogeneity. 3D containing soil were transferred into standard calorimetry ampoules incubated isothermal calorimeters monitor heat dissipation rates as proxy activity over 51 h at 18 °C. When among prevented, the most heterogeneous treatment showed lowest rates, despite having concentration. Compared conditions, rate from 110% lower beginning experiment (12.7 ?J s?1) 50% when reached peak (72.6 s?1). Moreover, delayed by approximately 2 compared treatment. allowed, effect strongly diminished. Our findings emphasize influence dynamics, highlighting importance including it cycling models for better understanding