Urea fertiliser encapsulation using natural rubber latex

Urea fertiliser encapsulated using natural rubber latex for the controlled release of urea has been prepared. Factors affecting the release rate of urea, for example, the type of rubber matrix, the concentration of sodium alginate used as the capsule coating agent, and the initial concentration of urea, were investigated. The lowest rate of urea released from the capsules was achieved using coated urea-unvulcanised rubber, from which the release was prolonged for ∼ 50 days. The maximum urea concentration incorporated in the coated capsules was ∼ 80% and the morphology of the prepared capsules was studied microscopically.