Fungal-fermented corn straw as an organic amendment: balancing tomato nutrition, soil functions and antibiotic resistance

Introduction Tomato growers need strategies that improve fruit nutritional quality and soil health while reducing dependence on synthetic fertilizers and wasting less crop straw. Fungal-fermented straw products (FSP) are a candidate amendment, but their suitable application rate, placement depth and side effects on soil microbes and antibiotic resistance genes (ARGs) remain unclear. Methods An FSP was produced from corn straw via solid-state fermentation for 30 d using Auricularia cornea cv. Yumuer. A single-season greenhouse pot experiment was conducted with an unamended control (no FSP) and six FSP treatments combining different rates (0.5–5% w/w) and soil incorporation depths (3 and 10 cm). Measurements included tomato yield (growth and fruit yield), fruit quality, soil health, biochemical responses, and molecular responses. Results FSP at 2% (w/w) incorporated to 10 cm increased yield by about 30% and raised fruit lycopene and vitamin C by 20–40% compared with the control. It also enhanced soil organic carbon, available P and K, humic substances and key enzymes, and shifted microbes toward decomposers and plant-beneficial taxa (e.g., Streptomyces , Sphingomonas , Nocardioides , and Arthrobacter ). A high surface dose (5% at 3 cm) increased total ARGs, whereas 2% at 10 cm achieved quality and soil benefits with ARG levels comparable to or lower than the control. Discussion These results suggest a practical application pattern that balances agronomic benefits with ARG-related risk for recycling crop residues in intensive tomato systems.