Dung beetles play valuable role in grassland management

Livestock farmers walk past piles of cow pats or sheep droppings every week, but when was the last time you took a closer look?

Rapid and thorough dung decomposition can have significant benefits for soil nutrients and structure, while also increasing the area available for grazing livestock.

Sarah Beynon, founder of Dung Beetles Direct, says in England an estimated 161,826ha or 4.8% of permanent pasture could be lost from production each year if cattle dung alone is not broken down.

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“In the UK, we have over 40 species of dung beetle. By feeding-on, breeding-in, shredding and burying dung, dung beetles can efficiently break down dung, which can deliver significant benefits to farming businesses.”

Heading up a recent Farming Connect dung beetle project, Dr Beynon organised a pilot release of nearly 2,700 beetles at set points throughout the spring and summer on three farms. The benefits of dung beetles included:

• Faster dung breakdown which increased the amount of available pasture for grazing
• Increased soil nitrogen which reduced the need for artificial fertilisers
• Higher pH which reduced the need for lime
• Increased soil P, Mg and K, which improved soil nutrient availability

Peter Williams: Great House Farm, Llansoy, Usk

Beef and sheep farmer, Peter Williams, who took part in the trial, admits he didn’t think he had any problems.

The trial at Great House Farm, Llansoy, Usk, involved fencing off a 20sq m area in a paddock so livestock could not access it. Dung beetle numbers were assessed using dung baited pitfall traps during a one-week period.

“After my attention was drawn to it, I noticed particularly on dry ground, the dung was not being broken down.”

The results showed existing dung beetles at the farm were increasing rates of dung breakdown by 46% in spring, 4% in summer and 31% in mid-summer on average.

However, after the additional dung beetles were released (2,500 in spring, 100 in early summer and a further 100 in mid-summer), dung breakdown increased by an additional 134% in spring and 13% in early summer on average.

But the benefits are not always visible, says Mr Williams. In spring, phosphorous soil levels were higher under dung pats with dung beetles than without (with = 50mg/litre, without = 45.5mg/litre) and the same was true in early summer (with = 43.5mg/litre, without = 34.5mg/litre).

Mr Williams has also altered his worm control protocol by reducing the amount of ivermectin used, as drenching with this chemical can kill the beetles.

“I had no idea how important dung beetles are until taking part in this trial, but without them we can’t go on. If you can’t get muck into the ground you can’t grow anything.”

Mr Williams’s next step is to monitor the fields to see if the population has increased and he hopes, in future, savings can be made by reducing the amount of fertiliser required.

Dung beetle decline

“As long as farm management practices don’t kill the beetles, the population should increase year on year, delivering more benefits,” says Dr Beynon.

However, dung beetle numbers are declining, she warns. Dr Benyon puts this down to changes in agricultural practices, intensification and the associated treatment of livestock with certain wormers, which are toxic to the beetles. 

“I believe the decline is largely due to more intensive patterns of anthelmintic and ectoparasiticide treatment of livestock, as well as fewer grazed, old, unimproved pastures and the upsurge of the short-term ryegrass monoculture.

“Chemicals that are toxic to dung beetles should not be routinely employed when livestock are at pasture, but selectively used and, if possible, used instead during housing, so the toxic dung does not come into contact with dung beetles.”