Dung beetles could be the answer
Could using exotic dung beetles help address soil health and water quality issues in New Zealand?
It’s an option that has real possibilities and potential.
Dung beetles provide multiple ecosystem services.
Those services include decreasing the amount of pasture smothered by faeces (pasture fouling), increased pasture growth, nutrient cycling, improved soil structure and control of pests and diseases.
On the basis of these benefits, New Zealand authorities have given permission for importation of dung beetles, which are now being mass reared here.
While dung decomposes naturally, intensive farming means large amounts of dung are dropped which can lead to environmental problems such as nutrients and pathogens moving into waterways.
Pasture production can also be reduced because of fouling.
However, dung beetles search out the faeces of animals, which they use for food and reproduction.
Most adult dung beetles make tunnels in the soil beneath the faeces, which they then bury to lay eggs in.
Other species make balls from the faeces which they roll away and bury deep beneath the soil surface before adding an egg.
As the eggs hatch the grubs feed on the dung so they break it down and eventually turn it into a sawdust-like material that actually adds to the fertility of the soil structure while all the time getting rid of dung sitting on top of the ground.
Beetles can also help reduce nitrous oxide emissions as some 80 per cent of the nitrogen content of dung is lost by volatilisation when dung remains on the pasture surface, compared to only 10 per cent following burial by dung beetles.
Greater pasture productivity is another benefit, as stock will not graze around dung pats, reducing pasture productivity.
Burial of nutritious material by dung beetles enhances grass growth, reducing reliance on fertiliser inputs.
Nuisance flies breed in dung but are out-competed for resources by fast dung burying beetles.
Dung beetles spread slowly after introduction and research is under way to find improved ways to increase their distribution in pasture, so they can help to reduce the effects of grazing animals on the environment.