Dung beetles making farms clean, green and productive

Beef producers are already under pressure to meet rising consumer expectations, but how worse off would they be without dung beetles? For starters, there would be a lot more flies and less enjoyment of the outdoors, but that’s just one way farmers and communities benefit.

The value of dung beetles was discussed at a recent event in Collie featuring expert Dr Shaun Forgie from New Zealand. “The biggest issue in NZ is the reduction in pasture productivity from huge concentrations of manure that foul the pasture,” Dr Forgie said. “The cowpat has a repugnant zone five times the size of a cowpat that animals avoid.”

By burying the dung in tunnels, dung beetles not only recycle nutrients and clear the way for pasture growth but also transfer nutrients and carbon below ground where they are less likely to be washed into waterways or lost to the atmosphere. These environmental benefits could help to address increasing consumer expectations for sustainable production and carbon sequestration. “New Zealand prides itself on being clean and green, but we have freshwater lakes contaminated with E. coli, while chemical and nutrient run-off is high. Part of the problem is the amount of manure sitting on the surface exposed to rainfall and run-off.  You can’t really call yourself clean and green when this happens.”

Another critical benefit to farming is helping to adapt to a drying climate. helps to increase rainfall infiltration and soil moisture while reducing run-off and soil erosion. Dr Forgie has first-hand experience with this benefit. “In one experiment we subjected a range of soils to a rainfall event. The results showed an 80% reduction in surface flow and a 91% reduction in sediment where dung beetles were on cowpats compared to cowpats without dung beetles and control treatments.”

One of the problems with permanent pasture systems is the difficulty of incorporating nutrients and soil amendments such as lime below the soil surface. Lime applied at the surface struggles to reach more acidic layers in the subsurface, while nutrients decrease with depth. Both of these issues may be limiting rooting depth and the ability of plants to grow later in the season when topsoil dries out. Tunnelling may improve root depth by pushing nutrients and amendments deeper into the soil. “If you can get nutrients down deeper you can improve grass root penetration. Activity also increases air space and oxygen and could lead to a significant improvement in productivity.”

It’s not just nutrients but also soil carbon that is buried, and this improves the soil’s ability to hold moisture and nutrients. Perhaps even more critical is the potential for carbon sequestration in soil and mitigation of climate change. One of the issues with carbon sequestration in permanent pasture is that topsoil levels are often near their limit, so it is difficult to increase. However, subsoil levels are typically much lower and have more potential to store carbon.  It is worth noting that different beetles tunnel to different depths, typically ranging between 10-40 centimetres in South West WA.

Benefits of dung beetles even extend to animal health because dung beetles directly or indirectly kill eggs and young larvae of parasitic worms. “Ultimately your reliance on drenches will be broken to the point where there is zero requirement, but because beetle numbers take time to bulk up (e.g. 5-7 years), you have to take an integrated approach for some time.”

The need for an integrated approach is also due to the harmful effects of anthelmintic antiparasite treatments on dung beetles, especially those excreted in manure or that persist in dung for a long time. Treatments excreted in urine appear least harmful. Where drenching affected livestock while beetles are active is unavoidable, farmers may need to reintroduce dung beetles to the property.

For more information on dung beetles and introducing them to your farm, contact Kathy Dawson at Warren Catchments Council on 0439 926 000 or email [email protected]. Information is also available at the ‘Dung Beetles in South Western Australia’ Facebook page and website.

The Collie event was facilitated by Warren Catchments Council in collaboration with Leschenault Catchment Council. This project is supported by Meat and Livestock Australia, through funding from the Australian Government Department of Agriculture and Water Resources as part of the R&D for Profit program.

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