Department of Soils, Punjab Agricultural University, Ludhiana, Punjab
*Present address: Department of Agronomy, Ohio State University, Columbus, Ohio 43210, USA
**Present address: Potash Research Institute of India, Vandhana, 8th Floor, 11, Tolstoy Marg, New Delhi 110 001
Downward movement of surface applied urea, with or without addition of commercial urease was studied in columns. Leaching was done with 8-cm water, maintaining 1 cm water-head on the soil surface, immediately or after 24 hours of urea application. Most of the urea leached down with the water front in the initially dry soil. In the soils maintained at 50% field capacity urea peak lagged behind the wetting front. A part of the applied N remained close to the surface when water was applied 24 hours after urea application, which was probably adsorbed as hydrolysed urea (NH+4). Application of the commercial urease prevented the urea from moving down the wet soil, but had little effect in the initially dry soil.
Urea leaching, urease activity
