Sulfur leaching from soil columns treated with S-35 labeled urine

Abstract

Pasture improvement has led to increased stocking rates which has potentially increased sulfur losses in urine patches and in sheep camps in merino enterprises. A study was undertaken using soil collected from a camp and non-camp area of an aeric ochraqualf soil. 35S-labelled urine was applied to these soils and the columns were leached daily for 7 days or subjected to wet/dry treatments for 7 cycles. The amount of S leached was dependent on the soil S level and the nature of the wetting and drying cycles. There were significant losses of unlabelled soil S in the leachate and retention of 35S in the profile which indicates that the sulfate in the profile moves en masse, most likely through continuously dynamic adsorption/desorption reactions.