Supplemental Data for: Crop diversity alters mineral-associated organic matter composition and its susceptibility to desorption.

However, MAOM composition progressively diverged across the crop diversity gradient. The perennial-inclusive system (WBCC) had higher relative abundances of lipids and lower proportions of N-bearing and phenolic compounds compared to monoculture wheat. In desorption incubations, WBCC soils exhibited MAOM mobilization following Pi addition, whereas wheat monoculture soils showed net sorption.

Pi-induced mobilization correlated positively with unclassified compounds and negatively with phenolics. Though MAOM formed under higher crop diversity exhibited greater susceptibility to Pi-induced desorption compared to wheat monoculture, this did not translate to higher C losses via mineralization. Our findings demonstrate that MAOM molecular composition is an early and sensitive indicator of soil responses to crop diversification and nutrient inputs, highlighting the importance of MAOM chemistry in regulating the balance between MAOM persistence and exchangeability.