The nexus of soil health, crop productivity, and environmental contamination, especially from microplastics (MPs), presents a complex challenge in sustainable agriculture. This dissertation explores the effects of various biosolids on soil health and crop growth, with a focus on mitigating the risks of organic pollutants and MPs in agroecosystems. Three experimental studies were conducted to investigate the potential of raw and treated biosolids, including the development of hydrochars from sewage sludge (SS) and chicken manure (CM), and their impact on the growth of soybean and corn, as well as the presence and effects of MPs in fertilizers and soil. In the first experiment, hydrochars produced from SS and CM at two temperatures (125°C and 225°C) were compared with conventional phosphate fertilizer. Results indicated that low-temperature hydrochars significantly increased crop biomass and soil phosphate availability, potentially offering a sustainable alternative to traditional fertilizers. The lower temperature hydrochars improved dry biomass significantly, indicating their direct nutrient supply efficacy. The second study quantified MPs in organic fertilizers, revealing high variability in MP abundance and composition. Composts displayed between 13,600 to 61,850 MPs per gram, with the quantity and size distribution of MPs being influenced by the feedstock and treatment conditions. Notably, organic fertilizers contained the highest MP levels, emphasizing the urgency for monitoring and managing MP pollution in fertilizer inputs. The third experiment assessed the impact of polyethylene microplastics (PE-MPs) on lettuce growth in hydroponic and soil systems. Degraded PE-MPs were shown to have a more detrimental effect on plant health, affecting photosynthesis, respiration, and nutrient uptake. Metabolomic analysis revealed substantial shifts in vital plant metabolites, indicative of defensive responses and stress adaptation. These findings highlight the need for sustainable soil amendment strategies that consider environmental contaminants, like MPs, and their complex interactions with soil and plant systems. They call for a reevaluation of biosolid use in agriculture and stress the importance of treatment processes to mitigate potential risks. The research underscores the imperative of developing integrated solutions to enhance soil health, ensure food security, and protect ecosystems from emerging contaminants