Insight into\nRedox Sites and Intermolecular Interactions\nof Soil Dissolved Organic Matter through Diverse-Compost Applications\nUsing VSOMM2 and Schrodinger

Substituting chemical fertilizers with compost is anticipated\nto\nfacilitate the disposal of organic waste and mitigate nonpoint source\npollution. However, research investigating the impact of diverse-compost\nutilization on the chemical reactivity of soil at the molecular-level\nremains lacking. Herein, the quantification and identification of\nmolecular-scale redox sites and intermolecular interactions of soil\ndissolved organic matter (DOM) using diverse composts during a crop\nrotation cycle were investigated using the unified theoretical modeling\napproach VSOMM2 and Schrödinger. Results showed that compost\nuse considerably altered the molecular weight and composition of soil\nDOM. In particular, we successfully optimized the validity coefficient\nof the unit model’s molecular number to construct 38 molecular\nmodels of DOM molecules to identify and quantify the distribution\nof redox sites and intermolecular interactions within soil DOM molecules.\nMoreover, the distinct roles of different composts in modulating redox\nmolecules within the soil DOM were determined during a crop rotation\ncycle. The application of cow manure compost considerably increased\nthe quinone, Ar–COOH, and Ar–SH contents in Model(EAC+),\nwhile application of food waste compost enhanced the Ar–OH\nand Ar–NH<sub>2</sub> in Model(EDC+). Finally, rotatable bonds,\ncation−π interactions, aromatic H-bonds, π-stacking,\nand salt bridges were identified to facilitate electron transfer within\nthe redox molecules of soil DOM, which can be further enhanced via\ncompost use. The findings of this study provide insights into the\nenvironmental biochemical reactions involving microcatalysts, metal\nreduction fate, pollution fate, and molecular composition of soil,\nproviding a theoretical basis for enhancing soil reactivity using\norganic fertilizers instead of chemical fertilizers.