Effect of surface application of urea, ammonium-sulfate and lime on exchangeable cation distribution in an inceptisol in humid tropical Queensland

Abstract

The effect of two sources of N (urea and ammonium sulfate) on the leaching of exchangeable cations in an Inceptisol was examined in the field over a 6 week period. During this time, artificial rainfall (60, 80 and 90 mm) was applied on three occasions to enhance the rate of leaching of exchangeable cations. This was assessed by taking soil samples prior to, and 2 days after, each irrigation. By the end of the experiment, about 50% of the applied N had been lost from the top 20 cm of the profile. Ammonium sulfate caused exchangeable cations to move from the 0-5 cm layer, but urea had no effect on cation distribution. The effects of lime application were confined to the upper 10 cm of the soil profile.