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More nitrogen in crops

Ricardo Bortoletto-Santos Polymer-coated urea (in blue) loses less nitrogenRicardo Bortoletto-Santos

Nitrogen is an essential nutrient for many crops, such as corn, wheat and coffee. Farmers supply it to plants by way of urea, a fertilizer that contains 43% to 46% nitrogen. The problem is that nitrogen volatilizes easily, losing up to 50% of its composition within 14 days of application. Researcher Ricardo Bortoletto Santos, a doctoral candidate at the São Carlos Chemistry Institute of the University of São Paulo (USP), is looking for a possible solution to that impediment: coating urea granules with a polymer. Conducting his research at Embrapa Instrumentation, also in São Carlos, on a team headed by materials engineer Cauê Ribeiro, Santos used a polyurethane made from two oils, castor and soybean, to coat the urea. “With a 7% polymeric coating (70 grams of polyurethane to one kilo of fertilizer), nitrogen losses dropped to 13% in laboratory tests, in 42 days,” he says (Journal of Applied Polymer Science, September 2016).