Yumei Peng Zi Wang Jia Shi Xiang Wang
ABSTRACT
Organo-mineral interactions are crucial for soil carbon sequestration, but the stabilization of mineral-associated organic carbon (MAOC) to fresh carbon inputs remains uncertain. Using 13C isotope tracing, we investigated the destabilization potential of contrasting carbon substrates (glucose versus oxalic acid) on MAOC persistence in three cropland soils (black, paddy, and loess soils). The cumulative CO2 caused by glucose was much higher than that caused by oxalic acid in all three soils due to preferential substrate utilization. Substrate-specific priming effects (PE) of MAOC were observed across three soil types. Compared with the control, cumulative PE in glucose exhibited divergent responses, with positive PE in black (2.98 %) and loess (220.48 %) soils, but a negative PE in paddy soil (− 33.2 %). Conversely, oxalic acid induced uniformly positive PE across all soils, with 121.66 % in black soil, 23.65 % in paddy soil, and 152.53 % in loess soil, respectively. Higher thermal stability, the highest ratio of MAOC to the specific surface area of muffled soil, and enriched aromatic C groups (C––O, Ar–C–C(H)) in paddy soil MAOC corresponded to its higher stability, as evidenced by its resistance to glucose-induced priming. By contrast, oxalic acid universally stimulated MAOC destabilization via mineral chelation. Our findings demonstrate that carbon sequestration strategies in agroecosystems must account for both substrate properties and soil-specific mineral-organic associations to optimize MAOC stabilization.
Substrate-specific priming of mineral-associated organic carbon in various.pdf