Cover crop diversification alters microbial life-death cycle and enhances carbon sequestration in agricultural soil

Sequestering atmospheric CO2 within soil organic matter via shifts in agricultural practices represents a compelling strategy for enhancing soil ecosystem services and mitigating global change. Traditionally, the perception of soil carbon (C) stability is focused on intrinsic characteristics of organic matter inputs, such as lignin content. However, recent studies challenge this perspective, proposing a more effective approach centered on managing how the soil microbiome processes C inputs (Sokol et al., 2019; Poeplau et al., 2019).

This shift prompts an exploration into the intricate connection between aboveground plant communities and belowground diversity of the microbiome, as well as the associated metabolic processes governing C sequestration. Building on this, Lehmann et al. (2020) presented a theoretical framework that interprets the persistence of C in soil as a consequence of interactions between the molecular variability of organic matter input and the spatio-temporal microbial heterogeneities within the soil system. This perspective underscores the need for a comprehensive understanding of the dynamic interplay shaping C sequestration, moving beyond static views of organic matter stability.

Therefore, within the EnergyLink framework various microbial markers were investigated to shed light on potential physiological changes at a microbial level across several European agricultural field sites with different cover crop management types. Specifically, to discern shifts in microbial necromass composition and quantity, we focused on amino sugars (galactosamin, gluctosamine, mannosamine and muramic acid). To evaluate effects on potential growth rates, we quantified ¹⁴C incorporation into ergosterol for fungi and ¹⁴C-leucine incorporation for bacteria. Comprehending changes in uptake strategies, we examined extracellular enzyme activities for different nutrient classes. Additionally, we determined C:N:P ratio for bulk soil and microbial biomass. Here we present first results and discuss implications of diversified cover crops on soil carbon properties.