Fertilizer quality and labile soil organic matter fractions are vital for organic carbon sequestration in temperate arable soils within a long-term trial in Switzerland

• Bulk SOC increased under long-term organic fertilization. No accumulated in the MAOM fraction (<6.3 µm) over a 36-year period. increase fertilization was solely attributed to labile POM fractions. oPOM-C contents are highly dynamic and depend on farming system. Agricultural management of soils has led severe losses soil matter (SOM), accompanied by an release CO 2 into atmosphere reduction fertility. Especially aspect global warming increasing demand for food, there is need sustainable options carbon (SOC) storage agricultural soils, but knowledge gaps exist regarding C persistence in, its transfer between functional pools, within different systems. Here we report impacts systems temporal dynamics SOM fractions DOK trial (Switzerland), from 1982 2017. A purely minerally (CONMIN), organically (CONFYM), fertilized system (BIODYN) were compared with unfertilized control (NOFERT). We separated archived Haplic Luvisol (0–20 cm depth) particulate (POM) mineral-associated OM (MAOM) fractions, via physical fractionation, analyzed chemical composition selected solid-state 13 CPMAS-NMR spectroscopy. demonstrate that none systems, additional sequestered clay-sized period 36 years. In all amount this pool did not change, strongly decreased NOFERT (-27%). BIODYN (+13%) CONFYM (+5%), CONMIN (-8%) (-20%). As no fraction, implies bulk increases stored NMR spectra showed comparable compositions Differences fertilizer quality (BIODYN = composted farmyard manure vs stacked + mineral fertilizer) omission pesticides resulted better conditions stabilization consequently significantly higher occluded (oPOM) aggregates, BIODYN. However, at high risk being lost few days, as illustrated strong annual content fluctuations depending timing sampling after harvest. The highest post-harvest indicate CONFYM. It anticipated only methods continuous application fertilizers long-run can maintain elevated levels, thereby ensuring also illustrates prevention major careful could associate fine particles later stage thus contribute OC sequestration stable pool. Overall, potential arable accumulate questioned.