Potentially Toxic Elements in Fertilizers and Associated Risks for Soil Organisms: A Bibliometric and Meta-Analytical Assessment

Soil contamination by potentially toxic elements (PTEs) from fertilizers represents a major issue threatening agricultural sustainability and global food security. This work conducted a bibliometric analysis and a meta-analysis on the occurrence of As, Cd, Cr, Cu, Pb, Zn, Ni, Co, Mn, Hg, and Fe in fertilizers and their implications for soil biota through risk assessment. The database used was Web of Science, and R software version 4.3.2 (bibliometrix and metafor packages) was utilized to perform bibliometric analyses (1116 documents) and meta-analysis with a five-year filter (548 articles). A total of 45 articles met all the inclusion criteria for the meta-analysis. The risk assessment was based on a quotient risk approach, considering high and low fertilizer application rates, as well as the average and maximum reported metal concentrations. Legal limits were surpassed for Cd in phosphate rock; for Cd, Cu, Cr, and Zn in manure; and for Cd and As in compost. Overall, organic sources presented a higher risk than mineral ones, with major risks related to mid- to long-term applications. These findings highlight the urgent need for strict regulation of contaminants in fertilizers and technical legislation grounded on ecotoxicological data to preserve soil quality and promote agricultural sustainability.