Controlled and Prolonged Release Systems of Urea from Micro-and Nanomaterials as an Alternative for Developing a Sustainable Agriculture: A Review

The world population requires the increase of food products from agricultural fields and also the improvement of agricultural practices to avoid the environmental pollution. Urea is the most used fertilizer worldwide; however, it is lost to the environment by processes such as leaching, volatilization, and denitrification. As an alternative to avoid these losses, controlled-release fertilizer (CRF) and prolonged release fertilizer (PRF) have been proposed. With this type of system, the plants could take the necessary amount of nutrients for their growth at the same time decreasing the environmental pollution. These systems could be fabricated from both synthetic and natural sources, such as wheat gluten proteins, polysaccharides, and composites (polymeric matrix, wheat-gluten-urea mix, among others). This review gives a sustainable agriculture approach in the application of CRF and PRF using inorganic and organic raw materials, focusing on the use of wheat gluten proteins and urea for the development of these systems.