Addition of vermicompost and pond sludge improves the quality of growth media based on green waste compost for Stevia rebaudiana Bertoni seedlings

Composted green waste (CGW) is commonly used as a growth medium; however, its application is often limited by nutrient imbalances, high pH, and elevated electrical conductivity (EC), which can hinder plant growth. Incorporating vermicompost (VC) and pond sludge (PS) into CGW has the potential to improve its nutrient profile and suitability for cultivation. This study investigated the synergistic effects of VC and PS amendments on the growth performance of Stevia rebaudiana Bertoni (stevia) when used as enhancements to CGW. A factorial experiment was conducted with varying levels of VC (0, 10, and 20%) and PS (0, 10, and 25%) to evaluate their impact on key growth parameters, including above-ground and root biomass, root length, plant height, and chlorophyll content, over a 90-day cultivation period. Results revealed that the combined application of VC and PS significantly improved stevia growth and nutrient uptake, with the 10% VC and 10% PS treatment yielding the highest plant height, biomass, and overall growth performance compared to unamended CGW. In conclusion, CGW amended with 10% VC and 10% PS represents an optimal formulation for enhancing stevia growth, with broader implications for improving growth media in sustainable agriculture.