Currently 50-80% of nutrient (nitrogen, phosphorous) added to crops via fertilizer addition is lost to the environment via atmospheric emission and leaching. Not only is this a significant financial cost, it is also a contaminant, degrading the environment i.e. algal blooms etc. We are developing novel materials and methods to encapsulate urea fertilisers to increase efficiency of nitrogen use by crops and reduce losses to the environment. The capsules are stimuli-responsive such that the urea is released to the environment when optimal for the plant i.e. at changing pH, temperature, moisture content, ionic strength.