Mechanosynthesis of urea-hydroxybenzoic acid cocrystals as sustained-release nitrogen fertilizer

Nitrogen is a key nutrient source in agriculture, which has a crucial impact on crop productivity. Out of available nitrogen fertilizers, urea is identified as the major nitrogen source, accounting for similar to 60% of global use. However, due to the low nutrient usage efficiency of urea, it has become unsustainable, as 50-70% nitrogen applied is lost due to leaching, volatilization and nitrification, causing a series of environmental hazards and economic losses. Moreover, the recent global pandemic as well as war disrupt the food supply chain and fertilizer market. Here we used mechanochemistry to prepare a series of novel urea cocrystals that showed sustained-release behavior with significant improvement (similar to 4 times), lower volatilization, and improved hydration stability compared to commercial urea. Therefore, the proposed urea cocrystal based fertilizer system demonstrates a potential sustained-release nitrogen source in agriculture where excessive use of fertilizer and nutrient loss can be minimised. Mechanosynthesis of urea hydroxybenzoic acid cocrystals/salt showed improved hydration stability and sustained-release behavior. Therefore, cocrystallisation of urea can be considered as a potential tool to minimize its excessive use.