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Technology developed by Embrapa, Unaerp, Unesp, and USP uses castor oil and nanoclay to control urea release, retain nitrogen longer in the soil, improve plant absorption, increase biomass production in tests with piatã grass, and reduce environmental losses linked to traditional nitrogen fertilizer use
Researchers from Embrapa, the University of Ribeirão Preto (Unaerp), São Paulo State University (Unesp), and the University of São Paulo (USP) have developed a Brazilian innovation to make fertilizers more efficient.
The group created a coating with a polymer derived from castor oil and mineral clay. This layer makes urea release nitrogen in a controlled manner.
In greenhouse tests with piatã grass, the technology improved nitrogen absorption by plants.
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The coated fertilizer also generated more biomass than common, uncoated urea.
Brazilian coating controls urea release
Urea leads global use among nitrogen fertilizers, mainly because it contains about 45% nitrogen by mass.
However, its high solubility in soil creates a significant agronomic challenge.
Under normal conditions, the fertilizer dissolves quickly and contributes to significant environmental losses.
According to researcher Caue Ribeiro, from Embrapa, this process increases ammonia volatilization and nitrous oxide emissions.
This gas intensifies the greenhouse effect, which underscores the importance of more efficient technologies.
Tests show significant difference in nitrogen
In water release tests, uncoated urea released over 85% of its nitrogen in just four hours.
As explained by Professor Ricardo Bortoletto-Santos from Unaerp, the coating with only polyurethane slowed down this process.
In this case, the fertilizer released about 70% of its nitrogen in nine days.
However, the incorporation of just 5% montmorillonite mineral nanoclay drastically changed the result.
With this composition, the fertilizer released only 22% of its nitrogen in the same period.
Nanoclay acts as an intelligent barrier
The internal structure of the coating explains the performance difference.
According to Caue Ribeiro, the nanoclay creates a kind of intelligent barrier within the coating applied to the granules.
In practice, it hinders water passage and chemically interacts with the released nitrogen.
This way, the nutrient remains retained longer and reaches the plants gradually.
This pace more closely matches the absorption capacity of crops.
Research overcomes urea’s environmental challenge
The innovation created a thin, continuous, and homogeneous layer around the urea granules.
This coating, similar to plastic, directly boosted fertilizer performance.
The system also used renewable and biodegradable polyurethane, derived from castor oil.
The matrix received small amounts of montmorillonite, between 2% and 10% relative to the mass of urea.
According to Bortoletto-Santos, this clay has a lamellar structure, similar to stacked platelets on a nanometric scale.
Piatã grass absorbs more nitrogen in tests
In greenhouse experiments, the nano-clay coated fertilizer increased dry matter production.
It also significantly increased total nitrogen absorption.
According to researchers, the rate reached double that recorded in the control fertilized with uncoated urea.
Therefore, the results highlight the role of nanostructure in nutrient use efficiency.
At the same time, the technology can reduce environmental losses linked to the use of nitrogen fertilizers.
Next step targets the productive sector
Now, researchers are looking for partners to bring the coating to the productive sector.
The proposal seeks to advance with a sustainable alternative for the next generation of controlled-release fertilizers.
With thinner coatings and preserved performance, the technology can make urea use more efficient in the field.
Can this type of Brazilian fertilizer change the way nitrogen is utilized by agriculture in the coming years?
