Effect of poly(butylene adipate-co-terephthalate) (PBAT)-coated urea on nitrogen release, greenhouse gas emissions, and residual behavior in soil

Urea, a widely used nitrogen fertilizer, rapidly releases nitrogen into a soil, reducing nitrogen use efficiency and causing environmental issues such as greenhouse gas emissions and nitrogen leaching. To address these issues, controlled-release fertilizers such as polyethylene (PE)-coated urea have been developed to regulate nitrogen release kinetics. However, PE coating remains in soil and contributes to microplastic contamination. Therefore, this study evaluates the viability of polybutylene adipate- co -terephthalate (PBAT)-coated urea as a controlled-release fertilizer. The nitrogen [ammonium (NH 4 + -N) and nitrate (NO 3 - -N)] releases, greenhouse gas (CO 2 , CH 4 , N 2 O) emissions, and residual behavior of PBAT-coated urea (PBAT urea) in soil were compared with those of conventional urea (Urea) and PE-coated urea (PE urea) under aerobic (upland) and anaerobic (paddy) conditions. PBAT urea and PE urea delayed nitrogen release compared with conventional urea and continuously supplied nitrogen to the soil. In addition, both coated urea reduced greenhouse gas emissions compared with conventional urea. In particular, under aerobic conditions, cumulative nitrous oxide (N 2 O) emissions in the coated urea treatments decreased by 51.5–67.9% compared with conventional urea. After 7 months of incubation, terephthalic acid (TPA), a potential degradation product of PBAT, was not detected by LC-MS/MS analysis indicating that TPA did not accumulate to detectable levels under the incubation conditions of this study. Although PBAT-coated urea delayed nitrogen releases and reduced greenhouse gas emissions compared with conventional urea, long-term evaluation and additional verification under actual agricultural field conditions are required to assess the residual behavior and degradation of PBAT in soil.