Urea fertilizer with precisely regulable slow-release performance by complexing with random copolyester

Abstract

Slow-release fertilizers have been widely used to promote agricultural production with less losses to the environment. However, further achievement of fertilizer with precisely regulable release performance is still full of challenges, especially for the most used nitrogen fertilizer – urea. In this study, we provide a strategy for regulating performance of slow-release urea fertilizer (SRUF) based on inclusion complexation between biodegradable copolyester and urea via simply changing chain composition. The units of butylene adipate (BA) are copolymerized into the main chains of poly(butylene succinate) (PBS) to obtain a series of random copolyesters of poly(butylene succinate-co-butylene adipate) (PBSA). The crystallizability of PBSA declines with increasing BA content, leading to the longer slow-release time for corresponding PBSA/urea inclusion complex fertilizer. The monotonous, nearly linear relationship between chain composition and the slow-release performance of SRUF has been demonstrated, revealing the great potential to design SRUF with precise slow-release time. Consequently, pot trails in the lab are employed to evaluate the promotion effect of SRUF on Brassica chinensis L.. The growth indexes of plants significantly increase with increasing BA content in PBSA chains used in SRUF of inclusion complex. The plants reach about twice of dry weight in optimized group by referring to neat urea group when the SRUF shows a release duration closely matching to the growth cycle of Brassica chinensis L.