Plant residue quality regulates its incorporation into soil aggregates and organic carbon stabilisation

• The incorporation of residue-derived C can be divided into three critical stages. • Hemicellulose content regulates residue decomposition in the partitioning stage. • P and cellulose contents are key regulators in stabilisation of residue-derived C. Plant residue input is vital for soil organic carbon (SOC) formation and stabilisation. While soil aggregates serve as fundamental units for SOC physical stabilisation, residue-derived C distribution among aggregate fractions and the factors regulating this complex process remain unclear. In this study, the effect of plant quality on the distribution of residue-derived C within soil aggregates was evaluated in a 120-day incubation experiment using various parts of 13 C-labeled maize straw (root, stem, leaf, sheath, husk, and cob; P content: 0.04–0.11 %; cellulose content: 25–33 %). Residue-derived C flow was divided into three stages: partitioning, transformation, and stabilisation. In the partitioning stage, residue-derived C was initially distributed across all aggregate fractions and subsequently declined in all fractions due to residue decomposition and CO 2 emissions. In the transformation phase, the 13 C content in small macroaggregates increased by 0.13 g 13 C kg −1 , reflecting transfer from other aggregate fractions. Finally, residue-derived C in small macroaggregates was further transferred to the silt + clay-sized fraction. The residue hemicellulose content was positively correlated with 13 C transfer into large macroaggregates and the silt + clay-sized fraction in the partitioning stage. In the transformation phase, residue-derived 13 C in small macroaggregates increased with increasing plant P contents. During the stabilisation stage, the cellulose content was negatively correlated with 13 C in the silt + clay-sized fraction. This study highlighted three critical stages of residue-derived C dynamics in soil aggregates during decomposition and identified plant P and cellulose contents as key regulators of residue-derived C stabilisation in soil aggregates.