A scheme covering an environmentally sensitive valley in the Marlborough Sounds is using dung beetles to reduce the emissions impact of cow dung.
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Source: NZ Farm Life Media

Karen Morrison and four of her neighbours have worked together to release dung beetles in the past few months in a bid to boost numbers faster and make a difference on their farms and the catchment.

She farms at Linkwater, a tiny community just five minutes from Pelorus Sound on one side and Queen Charlotte Sound in the other direction. Several dairy farmers farm the valley floor that runs between those two sounds. It is a spectacularly picturesque part of the country and because of its location, also environmentally sensitive.

Each farmer decided to buy two farm packs of the beetles and all have released them at the same times and worked together on the project. Each farm pack contained four different species of dung beetles recommended for the Linkwater climate, soils and type of farm. Beetles ranged in size, seasonal activity, even day versus night activity and dung preference.

“You open up a cow pat for some species and put them under and put it back on. For others you just sit them on top. We released the paua beetles (Geotrupes spiniger) on a warm day and they flew straight up and came down to another cow pat.”

Karen Morrison has been examining dung closely for signs of dung beetles.

One pack of beetles is recommended for a herd of 300 cows which is about the size of each of the farms in the Linkwater catchment. If they put just one pack of beetles on each farm, they expected to see results in five to seven years, whereas two packs for the size of their herds is expected to speed it up to between three and five years. Hence two packs each to increase the beetle population in the valley faster.

The first batches, each containing several hundred beetles, arrived in November, with further batches released in January, February and the last one in March.

“We got as many people as possible on board from the start to spread the beetles throughout the valley,” Karen says. “We’re enclosed in a little valley, so they’re not going to go out of the valley and it’s beneficial to everyone.”

The group went around each farm as the first of the beetles were released and the GPS coordinates of the sites are all on file with Dung Beetle Innovations that bred them as well as the Marlborough District Council.

The council is working with the farmers as part of the Te Horiere/Pelorous Catchment Restoration Project which the Ministry for the Environment has identified as an exemplar catchment. The project has been mapping streams on all properties throughout the catchment and measuring them for clarity, nutrients, sediment and E.coli. That has created a baseline that can be used for a monitoring and evaluation programme, with improvements made where they are needed.

As part of that process to make improvements, the project is providing a subsidy to farmers purchasing dung beetles. Each pack usually costs $6000, but that was reduced to $5000 for Karen and her group of farmers because they ordered 10 packs. The Te Horiere/Pelorous Catchment Restoration Project then provided a $2000 subsidy for each pack, which meant each farmer paid $3000 for each pack of beetles.

Because they are working with the council, Karen and her neighbours had their packs of beetles couriered overnight to the council’s offices in Blenheim to avoid the extra travel time for rural delivery. She collected the first batch from Blenheim and the council delivered the next batch to her which she then distributed to her neighbours. It was one of the many advantages of working as a group and also a good working relationship with the council.

“You have the same questions and we wanted to talk about dung beetles, so we got someone to talk to us and the council has put meetings together to answer our questions.”

Karen has high hopes about the dung beetles’ ability to improve pasture on the farm as well as the environmental benefits. Beetles tunnel into the soil, taking dung with them, which has a flow-on effect. Their tunnelling aerates the soil and allows water to penetrate better, which combined with dung increases grass root growth and biological activity. All going well, she expects the paddocks where the dung beetles have been released should have about 20% more pasture in four years, simply by having enough beetles to replace dung patches with grass.

“It will also mean we will put more dung into the ground rather than being washed off into the waterways. And because it has been put back into the soil, you shouldn’t have to use as much nitrogen in your paddocks or other fertiliser.”

She acknowledges they have yet to achieve those results, but she’s positive the beetles will have a beneficial effect on the farm and the environment. She has already found signs of the beetles in the paddocks beyond the release sites.

Karen and her family’s environmental work on the farm goes back much further than dung beetles and riparian plantings became the norm. She is the third-generation dairy farming on the Linkwater farm that today covers 115 hectares on the valley floor and edging up the sides of the steep surrounding hills. Taking out the rougher terrain and a bit of forestry, the family milks their Friesian herd on 84ha. A 15ha support block down the road winters the cows for 42 days and produces a cut of pit silage followed by a cut of hay. Young stock are sent away to graziers.

The support block flows down a gentle slope to the valley floor where it borders the road and the lower edge has the added challenge of natural springs. Combined with an annual rainfall of about 1.6 metres, the area “just made mud”. It prompted the Morrisons to fence 0.6ha of land for a wetland.

Another reason for establishing the wetland with a mix of native plants was to add to the corridor of native plantings in the area for native birds to follow. Other farmers in the area are doing similar plantings to build up that corridor.

“We used to have lots of tuis and wood pigeons around and they disappeared. Then a few years ago we planted shelterbelts for the cows and that brought more birds back. Since then we’ve looked at what else we can do to make things better like getting back eels in the creeks and freshwater crays.”

So far they have planted 0.4ha of it in a mix of plants from kahikatea and rimu through to flaxes and carex. Tastier species of their initial plantings were savaged by wild deer that came down out of the bush and forestry. They went back and erected deer fencing, with the Te Horiere/Pelorus project providing up to $10/m for materials.

A gate opens from the road to the wetland so that the public can walk into it and hopefully one day enjoy the plantings and birds. A walkway alongside the road is used by trampers to link parts of the Te Araroa Trail that travels the length of the country and Karen says a local craftsman has built a macrocarpa seat to place among the plantings.

They fenced waterways through the farm 13 years ago and more recently have been planting them with natives. Karen preparing sites and putting plants in the ground is a breeze – the hard part is managing them after planting.

In the farm operation, they are relatively low stocked and for the past 14 years have milked their 220-cow Friesian herd once-a-day (OAD). A summer crop gets the herd through summer on the unirrigated farm, with each cow getting 1kg palm kernel per day throughout the season. The result is about 1000kg milksolids (MS) per hectare.

The family moved to OAD milking by necessity because they were also running a contracting business back then and needed to free up time on the farm to do both. The Friesian herd was established by Karen’s grandfather, Michael, back in the 50s, so the family were keen to retain those genetics. It was made up of smaller-framed Friesians which helped in the transition to OAD and today the cows average between 500kg and 550kg liveweight.

Karen came back to the farm nine years ago to help out and has stayed. It follows a career in hospitality, including a three-year stint at Milford Sound and also working as a chef. She loved the social side and still does some casual waitressing in nearby Havelock.

Her semi-retired parents, Nigel and Christine, still help on the farm and the family employs one full-time staff plus a relief milker. It makes the farm somewhat overstaffed and means it is not the low-cost operation it would be without the higher wage. But it works for the family. Even with higher staff and that for about nine years now.”

Every three years they soil test every paddock on the farm and that has enabled them to target specific fertiliser applications to each paddock.

“We used to do the odd paddock, but one paddock would be great and the other would be rubbish, so testing every paddock shows us what they need. It’s a worthwhile cost. Instead of blanketing the farm with x amount, we can vary what goes on to each paddock and some paddocks don’t need anything.”

Karen says they have never used a lot of nitrogen and tend to apply it little and often, adding up to 100kg N/ha/year or less.

Into the cropped paddocks they sow a mix of species including One50 perennial ryegrass which they have found the best choice for their dryland farm. To that, they add plantain, chicory and white clover for the cows’ diet and to cover the paddock well. While the ryegrass is sown down the tines, the clover, plantain and chicory seed is blown out the front with an air drill to fill any gaps between seed rows.

It provides a mix that caters for a climate that delivers relatively high rainfall, but also dry summers. The farm averages 1.6m of rain a year and that’s the reason the family installed an above-ground, covered effluent tank. The 1.5 million litre tank is about half a million litres more than the herd needs but provides for the possibility of twice-a-day milking in the future if circumstances change.

This year, relentless rain fell on the Top of the South through late winter and early spring. It took its toll on the cows and instead of calving with the usual condition score of 4.7 or better, they had dropped to about 4. The cows were still building up condition going into mating and Karen gave them molasses for extra energy. Though the cows had a really good submission rate at mating, their empty rates were higher than they would have liked.

Silage is fed out when pasture is insufficient. In the past they grew maize for silage, but for the past three years they have cut grass silage and Karen says they have decided they need the maize. This year they are buying maize silage from a contractor to feed out in April and May to build the cows up for winter. She says the cost of buying it from a contractor or making it themselves works out about the same, but it is less work to buy it.

The cows are usually dried off about May 25 and head to the support block in the first week of June. They stay there 42 days, then head back to the milking platform to begin calving from July 20. It is an early start to the season, but milking OAD means they need the extra milkings to clear colostrum before putting the milk in the vat. Plus, they need the minimum 400l in the vat for the tanker to pick their milk up, so it means calving a bit earlier to get the minimum milk by the beginning of August.

By milking OAD, their first round takes them through to the second week of September and by then those first paddocks are starting to grow again well.

The calves from artificial insemination (AI) are straight Friesian bred for fertility and OAD milking capability. Friesian bull calves find a ready market, as do the Angus-cross calves that result from Angus bulls following AI. The farm buys two new Angus bulls each year from a neighbour and keeps them through to three years old. They also buy a Jersey bull each year from nearby Rai Valley to go over first calvers and the bull calves from those cows are the only calves that go on the bobby truck.

Their environmental focus now is planting more wetland areas and watching the dung beetles expand in numbers to do their job. OAD milking, they still milk 5am every day so they can get all the other jobs done and finish around 3pm.

They learnt a few tricks in their days contracting and one was growing a crop of Hunter brassica for summer feed. The hybrid is a cross between a turnip and Asiatic leaf vegetable which produces a leafy turnip usually grown for sheep.

“It was put in here by mistake one year when we had the contracting business and it was the best mistake we made. We can get two to three grazings off it through summer on dryland and we’ve been doing.

The nation’s power supply crisis and the prospect of rising prices are frustrating northern Victorian farmers.

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