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      New treatment “digests” dairy effluent
Grant and Scott Shaw and Semex Area Representative, Howard Hodgetts, inspect the well-functioning effluent pond at Hawova Holsteins, Finley, NSW. The use of a new “biologically active” microbial culture has significantly improved water quality, reduced odour and all but eliminated surface crusting on the effluent pond of a large-scale Riverina dairying operation. Brothers Grant, Scott and Brett Shaw milk about 700 registered Holsteins producing around 6.5 million litres of milk a year at Finley, NSW. The Shaws’ intensively-fed, Canadian-pedigree cows are renowned for their size and high production, but the by-product of this success has placed their effluent pond under severe pressure in recent years. “The yard and effluent pond were built for 300 cows but now we’re milking 700 cows in two groups twice a day,” Grant Shaw said. “There’s been a huge build-up of solids in the pond, which has buried the outlet valve. For the past couple of years, effluent has simply overflowed into a drainage channel instead of being flood-irrigated over our pastures. “The pond had a thick, hard crust on its surface that was almost strong enough to walk on. It smelt awful. Luckily, the prevailing winds are south-westerlies but when they blew our way you could smell it at the house. “It got to the stage where we had to clean the pond out every couple of months, which cost thousands of dollars each time. Within four or five months, it’d be back to what it was, so it was all a waste of time and money.” Last spring, the Shaws agreed to participate in a trial using BioAg Digest-it® for Dairies, a fermented culture that helps to create and maintain a balanced microbial environment in effluent ponds. Developed by Narrandera company, BioAg, it provides a rich source of dormant aerobic bacteria and an additional food source for microbes, thereby stimulating microbial digestion of organic matter. Depending on the thickness of the surface crust, a number of physical and chemical changes can be observed in ponds within four to six weeks of treatment. These include increased bubbling due to increased aerobic microbial activity and reduced surface crusting, turbidity, solids and odour. In the longer term, nutrients that are otherwise “locked up” in suspended solids are converted into a rich source of plant-available nutrients, which can be applied to pastures. This reduction in solids also reduces the need for desludging. The Shaws activated the pond by applying 20 litres of Digest-it® as a high-pressure spray to the crust and pond surface in mid-September. Since then, they have poured 1.5 litres of the product onto the concrete apron before it is hosed down after each morning’s milking. According to Grant Shaw, the result has been little short of amazing. “Digest-it® has done a great job on the pond,” he said. “The crust has disappeared, the water has cleared up and the constant bubbling shows that the solids at the bottom of the pond are being dissolved. Every now and then a big ball of solids pops up from the depths and gradually disappears. “There’s very little smell. You can push a stick into the sludge on the bottom and it doesn’t have that pungent smell of putrefaction that it used to have. “The outlet valve is still blocked so the water still overflows into a drainage channel, but at least it’s not green and thick like it used to be. In fact, it’s so clear that the other day I checked to make sure the irrigation gate was not leaking! “The water quality has obviously improved. It used to kill everything in the overflow channel, but now we’ve got grasses and weeds growing so I’ll have to spray them.” As an added bonus, birds are starting to return to the pond. Ducks have always camped on the crust but now a small flock of ibises is making regular visits. Grant said treatment with BioAg Digest-it® for Dairies was very cost-effective. “The cost is nothing compared to the cost of getting the pond pumped and cleaned out every couple of months,” he said. “The plan now is to get the outlet valve working again so that we can recycle the effluent, which is clearly of much higher quality than before, over our pastures. The pond would cope much better if we could get the water out sooner. “The way things are going we should be able to continue using this pond without enlarging it even if we continue to increase our herd size.” BioAg Digest-it® for Dairies is distributed by leading livestock genetics organisation, Semex Pty Ltd, which employs six full-time sales representatives throughout Australia. |
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