Assessing environmental impacts of various biofertilizers in Europe: A step toward circular economy transition

Composts, biofertilizers, and biostimulants are emerging as key solutions for sustainable agriculture, contributing to nutrient cycles closure and resource efficiency. This study evaluated the environmental impacts of three composts, three biofertilizers, and two biostimulants produced in Ukraine, Denmark, and Sweden using a life cycle assessment approach. The analyzed products include low and high biology compost, vermicompost, insect frass, digestate, biochar, fish hydrolysate, and compost tea. Environmental impacts were assessed from production to farm gate delivery, using functional units based on nitrogen, phosphorus, and potassium contents. To date, no comparative studies have evaluated biofertilizers, biostimulants, and composts based on their nutrient content, highlighting the novelty and innovative nature of this research.

The results revealed that digestate is the most environmentally favourable option for mitigating climate change impacts per tonne of nitrogen and potassium, while vermicompost is optimal for phosphorus due to its high intrinsic content. Fish hydrolysate has the highest impact on acidification, with potassium being the nutrient contributing more to this impact. Compost tea is the most water-consuming biostimulant, and it has the highest impact on eutrophication and land use per tonne of nitrogen, compared to the other products. Interestingly, biochar emerged as the least impactful in terms of acidification, eutrophication, land use, and water use across all three nutrients. Low biology compost, high biology compost, and insect frass are environmentally friendly options, demonstrating low impact across all categories. The sensitivity analysis results highlight the impact of nitrogen and phosphorus mineral fertilizer equivalents on environmental outcomes. Significant changes were observed in land use, freshwater eutrophication, and acidification, while climate change and water-use impacts remained stable.

Selecting the appropriate composts, biofertilizers, and biostimulants can enhance circularity and minimize environmental impacts. This study provides valuable insights to help decision-makers advance sustainable agricultural practices.