Restoration of Copper (Cu) Polluted Soil Using Compost and Vermicompost and Their Impact on Chili Growth

The phytoavailability of copper (Cu) in productive soils poses a significant threat to ecosystems, predominantly due to its extensive use in mineral fertilizers aimed at enhancing crop yield. To address this issue, a pot trial was conducted to evaluate the efficacy of compost (CP) and vermicompost (VC) induced from agro‐industrial waste byproducts, applied at rates of 1%, 3% and 5% to immobilize Cu in contaminated calcareous soil. This trial was arranged with seven treatments along with their three replicates following a completely randomized design. Results presented that CP and VC significantly reduced soil alkalinity by reducing soil pH by 0.45 and 0.38 units, respectively, over control. In addition, incorporation of CP and VC at 5% expressed efficient reductions in Cu mobility by 34.4% and 48.8%, respectively over control soil. Furthermore, significant reductions in Cu were noticed by 47% and 37.9% in chili shoot and root when CP at 5% was applied. Likewise, the addition of VC at 5% also showed the prominent reduction in Cu absorption in chili shoot and root by 62.2% and 49% respectively, relative to control polluted soil. Moreover, a prominent increase in soil nutrients was observed after the incorporation of CP and VC at 5% respectively, over nontreated soil. Furthermore, the greater increase in chili yield, plant biomass, chlorophyll contents, as well as nutrient absorption by chili tissues was observed primarily due to the greater soil nutrient availability provided by the CP and VC in alkaline Cu polluted soil. These findings demonstrate that CP and VC, as byproducts of agricultural waste serve as sustainable, eco‐friendly soil amendments for restoring soil health. They not only mitigate the phyto‐toxicity of Cu but also improve the alkaline soil nutrients status and reduce the dependence on synthetic fertilizers by naturally restoring soil fertility. Future studies will evaluate the long‐term effectiveness of CP and VC in field‐scale applications, their interactions with soil microbiota and their potential for broader crop systems.