Pig manure can replace phosphate fertilizer in agriculture
The War in the Middle East brought a warning to Brazil: in addition to the rise in the prices of inputs, essential for agriculture, the country's dependence on imported products.
Brazil purchases around 75% of the phosphate fertilizers it uses in agriculture on the international market. A vulnerability that researchers from Embrapa Agrobiologia (RJ) are working to reduce.
One of the most relevant inputs for agriculture, phosphorus directly influences plant growth, flowering, grain filling and fruiting. Its absence in the soil compromises productivity. The problem is that, unlike nitrogen, it cannot be captured from the air. Mineral reserves are finite and non-renewable.
The solution to this problem may lie in struvite, a mineral obtained from pig waste or urban sewage. It is a sustainable technology within the concept of circular economy.
Recent experiments carried out on soybean crops showed that the structure was able to supply up to 50% of the demand for phosphorus, maintaining productivity of 3,500 kilos per hectare, very close to the national average of 3,560 kilos per hectare recorded in 2025 with conventional fertilization.
According to the study coordinator, researcher Caio de Teves Inácio, the difference between struvite, in addition to its economic and environmental advantage, lies in the way it acts in the soil. It is a slow-release fertilizer, which combines well with the conditions of tropical Brazilian soils, which tend to quickly fix soluble phosphorus, making it unavailable to plants. The alkaline reaction of struvite contrasts with the acidity of traditional fertilizers, an additional advantage for predominantly acidic soils such as those in the Cerrado biome.
Waste becomes input
Struvite is formed by crystals of magnesium and ammonium phosphate, obtained by chemical precipitation of nutrients present in pig farming waste.
For medium and large pig producers, technology opens up the possibility of a new income. Embrapa estimates indicate that farms with more than 5 thousand animals have the potential to generate around 340 thousand tons of struvite per year in Brazil.
And it well represents the concept of circular economy, by transforming an environmental liability, which is animal effluents, into agricultural input with high added value. In addition to looking for a substitute for conventional phosphate, the research seeks to build a more autonomous production model, capable of recovering nutrients from the waste we generate, reinforces researcher and study coordinator Caio Inácio.
Researchers are also testing a more sophisticated version of the product: an organomineral fertilizer that combines struvite with organic matter, whose phosphorus diffusion experiments in the soil showed 50% greater results in the first 28 days compared to pure granulated struvite.
Another competitor for phosphates is in the automotive industry. The production of batteries for electric cars also requires the mineral, which can become more expensive.
Global market advances and Brazil takes its first steps
On the global stage, interest in struvite has grown exponentially in the last decade. More than 80 struvite production facilities were already operating around the world in 2019. Countries such as China, the United States and Germany lead research and innovation in the sector.
In Brazil, scientific knowledge about the mineral's performance in tropical conditions is still scarce. A gap that science seeks to fill.
The research is aligned with the National Fertilizer Plan and financed by CNPq. The next step is to obtain regulatory registration to enable the commercialization of the product in the Brazilian market.
In addition to Embrapa Agrobiologia, participating in the research are: Embrapa Solos (RJ), Embrapa Swine and Poultry (SC), the Federal University of Santa Catarina, Federal University of Santa Maria, University of Rio Verde and the Federal Farroupilha Institute.
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Source: CNN