<b>Code of Great achievable whole-profile sequestration potential of mineral-associated organic carbon in Chinese croplands</b>

Mineral-associated organic carbon (MAOC), characterized by due to its relatively slow turnover rate, playis a critical role inpivotal for long-term soil organic carbon (SOC) sequestration, supporcontributing to soil health, climate change mitigation, and therefore food security. However, the depth vertical distributions of MAOC storage and its sequestration potential across soil depths remain poorly understood, especially at large spatial extents. Here, we report a national dataset of SOC and MAOC measurements across seven sequential depth layers down to 2 m atfrom 365 cropland sites in Chinese croplands (nonexcluding -paddy fields) across China, sampling seven sequential soil layers down to 2 m. Our findings We showreveal substantial spatial variability in that the depth distribution of MAOC concentration with depth, s varies widely across the sites, strongly being positively correlated withto depth-specific soil carbon- to- nitrogen ratios and fine mineral particle contents (clay and silt). WhileAveraging across the sites, MAOC is the dominatesnt SOC across all sampled depthsfraction at all depths, but its relative contribution dominance diminishes eclines in deeper layers, particularly below 1 m, probably due to reducedlimited microbial activities in deeper soi layerstherein. NotablyAdditionally, we find that current average MAOC stockslevels only constitute &lt;25% of their attainable maximum MAOC, with even larger deficits in subsoils (0.3-2 m) exhibiting even greaterwith higher deficits in high-clay and /silt regionscontent. Nationwideal-scale mapping estimates a totalthat the SOC stock in the 0–2 m depth of Chinese croplands is of 11.4 Gt (95% confidence interval: 6.8–16.2 Gt) in the 0–2 m depth of Chinese croplands, with &gt;75% of this stock residing belowin the 0.3–2 m layer and MAOC contributing 55% to the total SOC. We project that an aAdditional 4.7 and 13.4 Gt MAOC can be sequestered in the 0–0.3 and 0.3–2 m depths, respectively, if properly managed. These findings underscore the untapped substantial potential for whole-profile carbon sequestration viain the form of MAOC accumulation in Chinese croplands. Achieving this potential will require , emphasizing the need of novel agricultural management strategies tailored to enhance MAOC formation and stabilization across the entire soil profile, with implications for climate-smart land management and national carbon neutrality goalsto reach this potential.