Impact of dung beetle activity on the quality of water percolating through Allophanic soil

Dung beetles are described as key ecosystem service providers. Because of ecosystem benefits from their activity, approval has been granted to import dung-burying beetles for release into pasture systems in New Zealand. Concerns remain, however, about the impact of dung beetle tunnelling and burying activity on the leaching of contaminants through soil. To assess the quality of water leaching from soil cores containing dung beetles, a trial was conducted using 12 intact Allophanic soil core lysimeters under in situ soil moisture and temperature regimes. Four lysimeters received dung and beetles (Geotrupes spiniger and Onthophagus taurus), four received dung and no beetles and four (controls) received no dung and no beetles. The quality of water was assessed by monitoring leachate samples for Escherichia coli and total N and P for 6 months. Key findings of the study were that concentrations of E. coli, N and P leaching through the lysimeters treated with dung beetles were not significantly different from soils without dung beetles. In addition, where dung was buried there was a significant decrease in E. coli and total N and P in surface soil compared with the lysimeters receiving dung only. Results from this study suggest dung beetle tunnelling and burying activity does not negatively impact the quality of water leaching through Allophanic soil.