Supplementary file 1_Contrasting responses of loamy and sandy soils to biodegradable plastic residues: microbial biomass, aggregation, and aggregate-associated carbon and nitrogen.docx

This treatment also increased macroaggregate abundance by 32% and 11% in the loamy and sandy soils, respectively, while decreasing the free silt–clay fraction. These changes were accompanied by higher C and N contents in macroaggregates, and also in sandy-soil microaggregates. Lower BDP doses produced weaker and more soil-specific effects, including increased microaggregate recovery in the loamy soil. δ¹⁵N progressively increased from macroaggregates to finer fractions in both soils, but was not affected by the presence of BDP.

In contrast, δ¹³C enrichment toward finer fractions occurred only in the loamy soil, demonstrating that soil characteristics, such as texture, may regulate C transformation and potential stabilization. Overall, BDP effects were dose-dependent and potentially modulated by soil properties. Although the strongest responses occurred at a concentration exceeding realistic annual inputs, detectable effects at lower doses highlight the need for long-term field studies evaluating repeated BDP incorporation.</p>