Impact of municipal solid waste compost on Spinacia oleracea L. (Spinach) Yield: Health risk assessment and dosing optimization

• Lower Municipal Solid Waste Compost (MSWC) concentrations enhanced soil health and crop growth but resulted in excessive heavy metal accumulation in crops, exceeding WHO permissible limits. • Compost quality depends on its Fertilizing Potential (FI) and Pollution Potential (CI). FI values met standards, but CI values indicated heavy metal pollution. • The Okhla Compost Sample (OCS) showed higher metal contamination than the Bawana Compost Sample (BCS). • Increasing MSWC doses raised soil metal concentrations, except for Nickel. Roots had higher metal accumulation than edible crop parts, but elevated MSWC levels caused unsafe metal levels in crops. • MSWC application at below 25% rate showed moderate pollution levels and is safer for agriculture. The increasing demand for effective Municipal Solid Waste (MSW) management stresses the importance of sustainable disposal approaches. Composting biodegradable solid waste offers such a solution, but it raises concerns about contamination with xenobiotics. This study evaluates the impact of Municipal Solid Waste Compost (MSWC) sourced from open landfills on agricultural soils and the yield of Spinacia oleracea L. (Spinach). The suitability of MSWC as a soil amendment was characterized using the Fertilization Index (FI) and Cleanliness Index (CI), while the risk of trace metal (TM) contamination was assessed through the Pollution Index (PI), Pollution Load Index (PLI), and Enrichment Factor (EF). The results show that MSWC application improved soil health but did not significantly enhance plant performance. Higher MSWC concentrations in amended soil increased TM levels, including Cu, Cr, Cd, Pb, and Ni, often exceeding permissible thresholds for soil and plant safety. At a 25% application rate, PI and PLI values indicated low to moderate pollution, while EF suggested no significant 33 accumulation of Cu, Cr, Cd, or Ni but moderate enrichment of Pb. The study infers that while MSWC can condition soil, its use must be carefully managed to mitigate toxicity risks. This research highlights the dual potential and challenges of using MSWC in agriculture, emphasizing the need for optimized application strategies to balance soil improvement with food safety.