Leaching and transformation of urea in dry and wet soils as affected by irrigation water

Summary The leaching losses of urea in dry and wet soils as affected by the irrigation water, were studied in 90 cm long and 5 cm diameter plexiglass columns. In dry sandy loam soil urea leached with irrigation water and peaks of urea were observed with water front but in sandy soil the wetting front moved faster leaving the urea peak behind. In initially wet soils the urea peak did not coincide the wetting front, following infiltration and after redistribution for 24 hours of infiltration. More urea was recovered in sandy soil than in sandy loam soil following infiltration and redistribution for 24 hours. Urea leached only upto 30 cm with 5 and 7.5 cm irrigation water whereas with 10 and 15 cm irrigation water profiles urea penetrated to deeper layers. The sub-surface application of urea did not change the leaching behaviour of urea. Urea behaves as a non-reacting ion like Cl with respect to its movement with soil-water before it is hydrolysed.