Designing sustainable soil conditioners: Nanocomposite-based thermoplastic starch for enhanced soil health and crop...

The growing demand for sustainable solutions in agriculture, driven by global population growth and increasing soil degradation, has intensified the search for sustainable soil conditioners. This study investigated the impact of adding nanoclay (NC) and nano lignin (NL) to thermoplastic starch (TPS) on its physical, chemical, and thermal properties, its effectiveness as a soil conditioner, and its resistance to UV-C degradation. TPS nanocomposites were prepared with varying NC (3 %, 5 %, 7 %) and NL (0.3 %, 0.5 %, 0.7 %) proportions and characterized by FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), TGA (Thermogravimetric Analysis), and DSC (Differential Scanning Calorimetry). Swelling tests, phosphate buffer solubility, cation exchange capacity (CEC), and UV-C degradation resistance were evaluated. Results indicated that incorporating 7 % NC (TPS/NC7%) significantly improved TPS's CEC and swelling properties. Conversely, adding 0.3 % NL (TPS/NC7%/NL0.3 %) improved photodegradation resistance and thermal stability. The TPS/NC7%/NL0.3 % nanocomposites also demonstrated superior water retention in soil, efficient absorption and controlled release of nitrogen, phosphorus and potassium (NPK) fertilizer, significant reduction in the leaching of NH₄⁺, H₂PO₄^-, and K⁺ ions, and antimicrobial activity against both Gram-positive and Gram-negative bacteria, highlighting their biodegradability and potential as soil conditioners to promote agricultural sustainability. Additionally, tests conducted on cherry tomatoes confirmed the effectiveness of these nanocomposites under real cultivation conditions, with improved seedling development when using the TPS/NC7%/NL0.3 % soil conditioner.