Lignin and fungal abundance modify manganese effects on soil organic carbon persistence at the continental scale

• DOI: 10.1016/j.geoderma.2022.116070
• Publication Date: 2022-08-03T18:49:14Z
• Authors: A.R. Possinger; K.A. Heckman; M.M. Bowman; A.C. Gallo; J.A. Hatten; L.M. Matosziuk; L.E. Nave; M.D. SanClements; C.W. Swanston; T.L. Weiglein; B.D. Strahm
• Keywords: Soil carbon; Cycling; Biogeochemical Cycle; Subsoil

Manganese (Mn) may play an outsized role in soil biogeochemical cycles relative to its abundance. The of Mn-facilitated oxidation biomacromolecules during litter decomposition is well-established, but the balance between Mn-promoted organic carbon (SOC) and long-term SOC protection mineral soils unknown, especially subsoils. In this study, we used collected across US National Ecological Observatory Network (NEON) assess distribution Mn relationships abundance concentration, potential mineralization, persistence at a continental spatial scale. Total reducible was not spatially correlated site moisture (Spearman's Rho = 0.24), highlighting that influence cycling independently from other moisture-driven chemical properties (e.g., reactive iron aluminum). However, effects on depended depth, soil, or site-level properties. particular, fungal:bacterial biomass ratio, proportion free light fraction, lignin abundance, and/or undegraded matter mediated effect metrics. For example, concentration subsoils shifted positive (approximately +270 % mean subsoil SOC) negative (−125 %) with increasing ratio. We propose convergence high Mn, lignin-rich substrates, ratio amplifies mineralization surface soils, does result higher net turnover due fungal stabilization. contrast, suggest promotes smaller, more persistent stocks by accelerating transformation particulate microbial pools.