Organic-inorganic fertilization regulates carbon sequestration-emission coupling through soil carbon fractions and...

Carbon sequestration and emission reduction in farmland ecosystems are central to sustainable agricultural development. This study evaluated whether organic-inorganic fertilization could coordinate soil carbon accumulation, respiratory carbon losses, crop productivity, and bacterial community structure in a semiarid dryland maize system.

Using a long-term fixed-site field experiment established in 2012, we compared five fertilization regimes during 2024 and 2025: no fertilization (NA), chemical fertilizer alone (CF), combined organic and chemical fertilization (SC), organic fertilizer alone (SM), and maize straw alone (MS). We measured maize productivity, soil total carbon and nitrogen, soil organic carbon and labile carbon fractions, soil CO₂ emissions, and bacterial community composition.

Fertilization increased grain yield and soil carbon and nitrogen pools, although its effects on the growing-season carbon budget differed among treatments. SC produced the highest grain yield, improved carbon emission efficiency, and maintained positive growing-season net ecosystem productivity within the accounting framework used in this study. Compared with NA, SC and CF increased grain yield by 235.4% and 195.3%, respectively. Although SM and MS increased soil carbon and nitrogen pools, neither improved the growing-season balance between crop production and respiratory carbon losses. MS produced the highest total carbon emissions and the most negative net ecosystem productivity. Fertilization primarily altered bacterial community composition through treatment-specific shifts in dominant taxa. SC and CF favored Gemmatimonadota-related groups, whereas MS enriched copiotrophic and substrate-responsive groups, including Proteobacteria and Bacteroidota.

These findings indicate that integrated organic-inorganic fertilization may be more effective than high organic-carbon inputs alone for coordinating maize productivity, soil carbon accumulation, and growing-season carbon performance in semiarid dryland maize systems.