Enhancing carbon sequestration in water stressed plant–soil systems through soil amendment with a Superabsorbent Nanocomposite derived from natural materials

Climate change and intensifying droughts represent a critical challenge to agricultural productivity and soil sustainability. This study evaluated the effect of two superabsorbent amendments with contrasting chemical compositions (polyacrylate-based polymer and a biodegradable polysaccharide nanocomposite) on carbon dynamics in common beans grown under drought conditions. The experimental design included analyses of morphological parameters, elemental composition, ¹³C allocation, and soil density fractionation. The results showed that drought drastically reduced biomass and nitrogen in leaves and roots, increased C:N ratios, and decreased root-derived carbon (RDC) incorporation, especially in stable soil fractions. The application of superabsorbents reversed these effects, increasing ¹³C translocation to roots and RDC in soil. NSN stood out for its ability to increase total RDC compared to the drought control parallelling the irrigated control in the heavy fraction associated with minerals, a key indicator of stable carbon sequestration. In contrast, Com mainly promoted flow to labile fractions, with less impact on stabilisation. These findings demonstrate that superabsorbents might be an effective tool for sustaining crop productivity and strengthening carbon sequestration in agroecosystems under conditions of increasing aridity.