Kari Ylivainio
Principal Scientist
Natural Resources Institute Finland
Finland
kari.ylivainio@luke.fi
Agriculture is the main source of external nutrients to the Baltic Sea, enhancing eutrophication, which is evident as algal blooms. The main nutrients causing eutrophication are nitrogen and phosphorus, which at the same time are essential for sustaining agricultural productivity. Therefore, these nutrients are applied via fertilization, but excessive application increases the risk of losses through volatilization or leaching.
Prior to World War II, fertilization was mainly conducted by using various organic nutrient-rich side streams, such as manures. However, population growth accelerated significantly from the 1950s onwards, putting pressure on agriculture to produce more food for the growing population. One of the main causes of increased productivity during the Green Revolution in 1960s was the increased use of mineral fertilizers. Since then, fertilization has commonly been conducted with mineral fertilizers, peaking in the 1980s. In the 1990s, fertilization recommendations were lowered to better match crop requirements, improving the utilization of phosphorus fertilizers and reducing nutrient losses to surface waters.
All this time, a vast amount of nutrient-rich side streams was produced but considered waste and not an option for replacing mineral fertilizers. Recently, however, there has been growing interest in turning nutrient-rich side streams into bio-based fertilizers (BBFs) to replace mineral fertilizers, decrease dependency on imported fertilizers, and reduce environmental problems.
In the Horizon 2020 -project LEX4BIO (https://lex4bio.eu/), we evaluated the potential of BBFs to replace conventional mineral nitrogen and phosphorus fertilizers in Europe. LEX4BIO focused on the most promising technologies for BBF production, their fertilization efficiency, and potential impacts on food and feed security and human health. The most important impact of the project was to provide technologies for developing safe BBFs, along with a policy framework for the EU’s transition to maximizing fertilizer self-sufficiency by using BBFs, while minimizing potential risks.
Screening of both available BBFs and emerging processing technologies, a wide selection of BBFs was tested, considering the new fertilizing products regulation (EU 2019/1009) that allows free movement of CE-labelled fertilizers across the EU. A total of about 40 nitrogen and 40 phosphorus-containing BBFs were selected for testing from laboratory to field scale. From a farmers’ point of view, the fertilization efficiency of BBFs compared to mineral fertilizers is a pivotal issue. Thus, both greenhouse and field trials were conducted in different climatic and soil conditions in Finland, Denmark, Germany, Austria, Hungary, France, and Spain to ensure comparability among different growing conditions. The results clearly showed that both nitrogen and phosphorus-containing BBFs can efficiently replace mineral fertilizers and thus reduce dependency on them.
The main concern for consumers is whether BBFs affect food safety. Potential heavy metals and organic contaminants, including pharmaceuticals, pesticides, and persistent organic pollutants (POPs; including PCBs, PAHs, PCDDFs and PFASs) are a major concern. A large screening of these contaminants was conducted for both the BBFs and the harvested crops. Heavy metal concentrations in the BBFs were below the limits set for the fertilizers and, in some cases, significantly lower than those in mineral phosphorus fertilizers, such as cadmium. Organic contaminants were also below the strictest limits set in the EU member states. From an environmental perspective, BBFs caused lower phosphorus losses than mineral fertilizers. One emerging concern relates to antibiotic resistance genes, which could potentially reduce the efficiency of currently used antibiotics. Although some BBFs contained pharmaceutical residues, these BBFs did not pose a risk of disseminating antibiotic resistance in the soil.
At the European level, nutrient-rich side streams could almost fulfill the crop requirement for phosphorus fertilization due to decades of overfertilization. However, this requires processing these side streams into more concentrated BBFs to reduce transportation costs from nutrient-surplus to nutrient-deficient regions. Unlike phosphorus, nitrogen fertilization is needed annually for optimal yields due to its leaching losses and the risk of ammonia volatilization. In the Baltic Sea region, data on the locations and amounts of these side streams is needed to evaluate their potential to replace mineral fertilizers.
All reports and publications of LEX4BIO can be found at the following link https://cordis.europa.eu/project/id/818309.