Phosphorus, a vital element to life, experiences a particular double threat: it faces both scarcity and excess in aquatic systems, the later causing eutrophication and damage to ecosystems. To address these challenge, scientists and farmers are looking for new solutions to ensure a more sustainable and efficient use.
Phosphorus is an essential element of life in our planet, found in bones, teeth, DNA, and RNA, and plays a critical role in vital processes such as photosynthesis, the nervous system, and muscular function. However, today we are faced with a paradox: on the one hand, the threat of its scarcity and, on the other, its overabundance, both with serious repercussions for our ecosystems.
In Chile, numerous lakes and rivers are already facing pollution challenges. The situation is exacerbated by high concentrations of nutrients from wastewater discharges, the lack of rural sewage networks, and wide-spread agricultural pollution caused by the use of fertilizers. It all underscores the urgency of adopting stricter global regulations. Countries like Denmark have implemented the “polluter pays” principle and Switzerland enacted a zero pollutant discharge policy. Chile authorizes phosphorus discharges into bodies of water with limit values between 2 and 15 mg/L.
Phosphate rock, which is clearly identified and accessible, is economically, energetically, and politically viable for mining and therefore can be converted into fertilizers and absorbed by plants. Despite its apparent abundance, only five countries control 88% of the world’s phosphate deposits: Morocco (with a dominant 75% share), China, Algeria, Syria, and South Africa. That dependency needs to be considered.
The phosphorus cycle goes from extraction to human consumption, including fertilizer and agricultural and livestock production, as well as food processing. However, the natural phosphorus production on Earth has been doubled, producing negative consequences.
When stored for thousands of years, phosphorus becomes more reactive, leading to the excessive growth of dependent organisms such as algae. This causes water eutrophication, with harmful effects such as soil degradation, pH alterations, massive proliferation of cyanobacteria, changes in salinity, and potential leakage into groundwater.
With more than 9.5 billion people to feed by 2050, and a trend towards diets rich in meat and dairy, demand for phosphorus will grow. However, phosphate is finite and its extraction is declining. Moreover, it is estimated that the overall efficiency of its use is lower than 20%.
It is key to manage phosphorus by developing sustainable fertilizers, ensuring coordinated environmental policies, optimizing its use in agriculture, and promoting a circular use of nutrients For example, organic fertilizers rich in phosphorus can be used in agriculture, such as derivatives of slurry treatment, manure, and biofertilizers from the agricultural and livestock sector. A strategy focused on the reuse of waste and the active involvement of all stakeholders will be decisive for sustainable phosphorus management.
For a more efficient use of phosphorus, the following options stand out:
Mycorrhizae as phosphorus collectors
Mycorrhizae, the symbiotic association between plant roots and fungi, can improve the nutrient uptake of plants. The fungi extend into the soil beyond the roots accessing and absorbing phosphorus from areas that would otherwise be unavailable to the plant. By establishing this relationship, plants have access to more phosphorus, reducing the need for excessive fertilizer applications.
Phosphorus-solubilizing bacteria and plant growth promoters
Some soil bacteria can solubilize phosphorus, converting unavailable forms of this element into forms that are easily absorbed by plants. These bacteria can also promote plant growth by producing plant hormones, improving soil structure, and fighting pathogens. Using these bacteria as biofertilizers can reduce dependence on chemical fertilizer and help make better use of the phosphorus in the soil.
Struvite
Eutrophication, caused primarily by phosphorus run-off into aquatic ecosystems has become a significant environmental concern. An emerging solution is phosphorus recovery from wastewater in the form of struvite, a mineral that is formed from elevated concentrations of phosphorus, ammonium, and magnesium. Once collected, struvite can be used as a slow-release fertilizer, efficiently recycling phosphorus and reducing its negative impact on aquatic ecosystems.
Controlled release fertilizers
Excessive use of fertilizers is one of the main causes of phosphorus overabundance in aquatic systems. Controlled release fertilizers are designed to gradually release nutrients such as phosphorus according to the plants’ needs. This not only uses phosphorus more efficiently, but also reduces the risk of run-off and therefore eutrophication.
In summary, the right balance in phosphorus use is essential to ensure agricultural sustainability and the health of our ecosystems. The alternatives explained here show a promising pathway to a more balanced and resilient future, where phosphorus is used efficiently and responsibly. It is crucial for farmers, scientists, policy makers, and consumers to work together in implementing these new solutions.
