Ethanolic Extracts of Karanja and Neem Seed Kernels as Effective Aids for Coating Karanjin on Urea

Urea coated with 10% (of urea-N) karanjin employing 5% of ethanolic extracts of Pongamia glabra or Azadirachta indica A. Juss (neem) seed kernels as coating aids, revealed over 40% inhibition of nitrification by the 45^th day over urea alone in laboratory incubation studies employing typic Ustocrept soil. Nitrapyrin alone was superior in this respect causing 67% inhibition at 5% level. Both the ethanolic extracts were superior to coal tar as coating aids for karanjin, with neem extract imparting better persistence. Karanja oil was not effective.