Study links soil microbial carbon metabolism to organic matter chemistry in temperate grasslands

A new open-access study published in Communications Earth and Environment examined 33 temperate grassland soils to understand how the chemical composition of organic matter affects microbial carbon metabolism. The researchers found that biomass-normalized rates of microbial growth and respiration are primarily linked to aliphatic compounds like carbohydrates and proteins, with a secondary link to unsaturated lignin-like compounds. This suggests that the specific chemistry of bioavailable organic matter plays a key role in determining how microbes process carbon in soils. The study also found that biomass-normalized respiration was positively linked to carbon in a reduced oxidation state, indicating a carbon-conserving catabolism process. However, microbial growth appeared unrelated to the oxidation state of carbon, suggesting that factors beyond simple energetic constraints control microbial growth in aerobic soils. These findings provide new insights into the processes governing the fate of carbon across different ecosystems, which is critical for improving soil carbon models and understanding carbon storage potential.