Assessing the Potential of Pomegranate Meal and Potato Waste as New Organic Amendments for Vermicompost

Abstract

ABSTRACTWaste disposal has become one of the greatest global concerns, which has high operational costs and might cause environmental pollution. Due to the lack of the organic matter in most of the Iranian agro-ecosystem, recycling organic waste materials favors the environment by reducing chemical fertilizers as well as improving soil structure and fertility. A vermicomposting system using cow manure (CM), pomegranate meal (PM) + sawdust (S), CM + potato waste (PW), PM + PW, CM + PM, and CM + PM + PW was set up to find a viable alternative raw material for improving physico-chemical properties of vermicompost after 60 days. The amended vermicompost of PM + S and PM + PW markedly improved the electrical conductivity (EC), which were below the EC limit (by 1.01 and 2.27 dS m−1, respectively), pH (by 7.04 and 6.60, respectively), and water holding capacity (respectively 1.9 and 1.2 times higher than CM). Vermicompost amendment led to significant reduction of organic carbon (OC), but nonetheless, PM + S and PM + PW showed higher OC content in the final product probably due to the higher initial carbon to nitrogen (C:N) ratio, raw material origin, and lower decomposition rate. In regard to nutrient value, the total phosphorus content in the end-product of PM + S and PM + PW was, respectively, 19.3 and 7.9 times higher compared with the final product of CM. Additionally, the amended vermicompost of PM + PW markedly improved total nitrogen content as compared with CM. The findings suggested that the additional amounts of nitrogen and potassium to PM + S and also potassium to PM + PW would improve the physico-chemical properties and fertilization of the final vermicompost considerably higher than CM vermicompost. This amendment has the potential to mitigate the adverse effects of vermicompost of CM, for example, salinity and alkalinity; and chemical fertilizers, for example, soil pollution with heavy metals in phosphate fertilizers, as well as the potential for soil rehabilitation.