Naturally Degradable Capsules Loaded with Pickering Emulsions for Slow Release of Liquid Nutrients

Liquid fertilizers with a high plant uptake and low energy consumption have aroused wide attention in the world for the agriculture industry. However, the slow release of liquid fertilizers remains a challenge because the molecules with an angstrom scale (e.g., urea) in water are easy to pass through the nanopores even in the hydrophobic encapsulating materials. In this study, a Pickering emulsion slow-release strategy is for the first time developed for the delivery of liquid nitrogen fertilizer. In the whole process, the Pickering emulsifier concentration and oil/water ratio are used to regulate the emulsion stability, leading to the slow release of liquid fertilizer in calcium alginate capsules encapsulated with urea-loaded water-in-oil Pickering emulsions (CUPEs), allowing for a rate of release to be achieved at 81.30% in 96 days in soil with a release curve that follows the “S” curve of plant growth, which is higher than the previous literature. More importantly, the CUPE-treated maize plants exhibit favorable growth conditions. Overall, this work presents an effective slow-release method and mechanism for delivering liquid nutrients, which is expected to open a new avenue for the effective use of agrochemicals to address population and environmental crises.