Oil-based polyurethane-coated urea reduces nitrous oxide emissions in a corn field in a Maryland loamy sand soil

Authors: BORTOLLETO-SANTOS, RICARDO - Embrapa; Cavigelli, Michel; Montes Muniz, Sheila; Schomberg, Harry; Le, Anh; Thompson, Alondra; Kramer, Matthew; POLITO, WAGNER - Embrapa; RIBEIRO, CAUE - Embrapa

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2019
Publication Date: 11/15/2019
Citation: Bortolleto-Santos, R., Cavigelli, M.A., Montes Muniz, S.E., Schomberg, H.H., Le, A.N., Thompson, A.I., Kramer, M.H., Polito, W.L., Ribeiro, C. 2019. Oil-based polyurethane-coated urea reduces nitrous oxide emissions in a corn field in a Maryland loamy sand soil. ACS Sustainable Chemistry & Engineering. 249(2020). https://doi.org/10.1016/j.jclepro.2019.119329.
DOI: https://doi.org/10.1016/j.jclepro.2019.119329

Interpretive Summary: Less than 50% of nitrogen fertilizers are taken up by crops. The remainder is susceptible to loss, thereby contributing to multiple serious environmental problems. For example, nitrous oxide, one form of nitrogen lost from agricultural systems, is a greenhouse gas and a catalyst of stratospheric ozone decay. Coating fertilizer particles may be one means of increasing the efficiency of nitrogen fertilizer uptake while also reducing losses, including nitrous oxide. ARS scientists and colleagues found that a novel polyurethane-coated urea performs similarly to uncoated urea for corn production while reducing soil N2O emissions up to 80%. These results will be of interest to fertilizer manufacturers, companies interested in reducing their global warming footprints, policy makers and anyone concerned about global warming and food production.

Technical Abstract: Urea is the most widely used N fertilizer due its high N concentration (46%), cost effectiveness and ease of handling. However, urea is particularly susceptible to N loss through volatilization and, like other forms of N fertilizer, is also susceptible to other losses including as N2O, a greenhouse gas and catalyst of stratospheric ozone decline. Polymer-coated fertilizers may be effective in reducing such losses but their effectiveness is largely unknown. We, therefore, developed a polyurethane coating for urea based on castor oil. To assess the appropriate coating thickness for field performance, we prepared urea granules with polyurethane coating (PCU) at 2% to 8% by weight. We tested the fertilizer value of these materials for corn (Zea mays L.) and measured field loss of N2O. Corn grain yield and N uptake were similar in treatments fertilized with urea (uncoated) and each of the coated materials. Cumulative N2O-N per unit of grain yield, however, was reduced by about 50% and 70% in the 6% and 8% treatments, respectively, compared with the uncoated urea treatment. Nitrogen uptake by a rye cover crop planted after the corn crop suggests that residual soil N was similar following all treatments. Results indicate that polyurethane-coated urea performs similarly to uncoated urea for corn production while reducing soil N2O emissions up to 60-80%, with an efficiency factor twice as high as that suggested by the Intergovernmental Panel on Climate Change (IPCC) for N fertilizers.