Soil amendment with biomass-derived carbon dots enhances rhizosphere organic matter, nutrient turnover, and microbial metabolism for maize growth

Soil degradation necessitates reducing the application of agrochemicals, while advancements in nanotechnology present growing opportunities in agriculture. Herein, this study synthesized a calcium- and nitrogen-co-doped carbon dots (Ca,N-CDs) with a high yield of 79.97% using the biomass of a submerged plant Potamogeton crispus . The soil application of Ca,N-CDs (100 mg/kg) significantly enhanced the growth (7.27–71.69%), photosynthesis, and antioxidant activity (29.49–173.20%) of maize ( Zea mays L.). In the rhizosphere microenvironment, the application of Ca,N-CDs enhanced soil pH and the turnover of organic matter and nutrients (nitrogen and phosphorus) by regulating related soil enzyme activities. Metagenome analysis revealed that Ca,N-CDs enhanced the diversity and evenness of the rhizosphere microbial community, particularly increasing the abundance of archaea, eukaryotes, and some beneficial bacterial groups ( Actinomycetes , Longimicrobia , and Micrococcales ). KEGG functional analysis, combined with metabolomics analysis, demonstrated that the microbial metabolic processes related to growth and reproduction were significantly enhanced by Ca,N-CDs. Changes in microbial communities and metabolism showed positive correlations with soil properties. Co-occurrence network analysis indicated that Ca,N-CDs changed the dominant microorganisms in the maize rhizosphere and strengthened their associations among themselves and with soil properties. The rhizosphere responses synergistically promoted the maize growth and development. These findings present a promising alternative for improving soil health and fertility as well as promoting sustainable agricultural production. • A high-yield CDs was developed using biomass from an aquatic plant. • Soli application of CDs promoted maize growth. • CDs improved the physicochemical properties of the rhizosphere soil. • CDs improved rhizosphere microbial community and metabolism. • CDs strengthened microbial and metabolic networks.