While New Zealand plays catch-up and Europe leads in using farm effluent, it was always going to fall to the North American continent to go large — very large.
The recent appointee to the Fonterra sustainability advisory panel says companies are finding as they change their sustainability practices it brings economic and environmental advantages.
Most of the dairy farms in the South Canterbury-based Pye Group run two-pond effluent systems with one settling pond and one aeration. Pye says Canterbury leads the way in such systems because it has had to, with the number of dairy conversions in the region.
James Emmett, who runs the Pye Group’s Grantlea Dairy No 1 farm, explains that all effluent from the shed goes into a settling pond. From there it flows to a second pond by way of a slightly upwards-sloping pipe to minimise the amount of solids flowing through.
The second pond has a constantly running electric aerator which is moved every couple of days. When the soil moisture is right the water from that pond is fed back to the pasture, he says.
Pye says every farm in the group has an effluent management plan, so that staff all know what the consents say, when they can put on effluent and when they can’t, what to do when a pump breaks down and how often they need to check the irrigators.
A computer program monitors everything, even down to sending an annual reminder to check the backflow preventers that keep clean water and effluent water separate in the system.
Emmett says he would love to have variable rate irrigators to apply the effluent, ensuring it only goes where you want it, and away from laneways, waterways and structures.
That would be his wish list “gold standard”, he says. “We do the best we can with the tools we’ve got.”
Eyeing the forecast, Emmett explains that every drain in the dairy shed leads into the effluent ponds so they must be managed to ensure they do not get so full that they are forced to pump out at the wrong time.
“We don’t want to be forced to apply effluent in wet weather because that’s when you get leaching and nutrient loss. We’ve just had rain. We’ve got a break in the weather and then Saturday we’ll have more rain. So tomorrow’s going to be my day when I target my drier paddocks and apply my effluent to them.”
Meanwhile, the solids ponds are also cleaned of sludge every two years, and that too is applied to the pastures, and is also part of each farm’s nutrient budget.
Pye says the group likes to do things itself so has bought its own effluent slurry spreader.
Emmett says it needs to be measured and monitored so they know exactly what is going back on the pasture.
“The best time is probably when you’re looking to re-seed or re-pasture so you can keep stock off it. Simple things like that -- good old-fashioned farming practice, use your head, use your gut, do what’s right.”