A Summer Oasis – Farmers Weekly

Don and Liz Polson have struck green on their Mangamahu Valley farm near Wanganui after spending $5000/ha on irrigation. Russell Priestreports. Photos by Graeme Brown.

A desire to improve lamb growth rates and drought-proof their finishing prompted the Polsons to install an irrigation system along with high-performance forages on their 130ha alluvial river flats.

“I’ve had enough of droughts,” Don says. “We’ve gone from a desert to an oasis under irrigation. We’ve never had so much summer feed.”

The Polsons’ main farm, Waipuna, is a 1600ha mainly medium to steep hill-country block lying between Mangamahu Valley and State Highway 4 (the Parapara Rd) north-east of Wanganui.

The farm includes 350ha of river flats and terraces bounded by the Mangawhero River. The area is prone to dry summers.

“In the past we’ve finished most of our lambs by various means. However, we’ve generally ended-up having to carry a lot of light lambs into the winter to finish,” Don says.

“My philosophy used to be that if we could get our lambs through the summer they would be very valuable.”

In recent years the Polsons have even fed grain or pellets to help carry their lambs through.

“We quite enjoyed feeding grain-pellets as it was nice to feel appreciated. The lambs would be waiting for you at the gate each day!”

Nowadays the focus is on getting lambs to slaughter weights as early as possible. To help them do this the Polsons have invested $5000/ha to irrigate some of the river flats.

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The option of buying more finishing land was also investigated but irrigation got the nod.

Don concedes that not everyone close to a major water source is able to irrigate because of the difficulty in getting water consents and in lifting it out of the river.

The irrigation project employs three guns, each covering an area of a little over 40ha and capable of delivering 30mm every 10 days. The required operating pressure is 120psi.

“Because of the high pressures required, guns are less efficient than centre pivots in delivering water. We couldn’t use centre-pivot technology because of the uneven contour.”

To achieve the required result two pumps are used in tandem. The first pump (30kW) lifts the water 30m out of the Mangawhero River and delivers it to the second pump (90kW) that provides the necessary volume and pressure to drive the guns. The Polsons have a consent to use 5300-cubic metres of water a day.

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Finishing lambs on irrigated red clover.

Paul Oliver of H&T Agronomics has been heavily involved in the species selection for Don and Liz Polson’s irrigated area. Red clover (35ha), plantain-white clover (20ha) and high-performance ryegrass-white clover (75ha) swards have all been sown.

Measurements of drymatter yield and liveweight gain have been recorded on each of the swards.

Red clover has shown to produce the greatest annual yield and consistently the best liveweight gain. It has generated spectacular performance results in summer, has a full range of weedcontrol options but is the least-robust plant at low residuals.

Also, all animals grazing it have to be vaccinated with 10-in-1 because of animal health issues related to clostridial diseases.

Ryegrass-white clover drymatter yield exceeded the other two swards in mid-winter to early spring but was the poorest performer over the spring-summer period.

It was the most robust sward of the three at low residuals but did have a greater requirement for nitrogen and water.

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It also achieved the poorest lamb growth rate. The Polson’s farming programme was considerably disrupted last winter when 20-30% of their river flats were covered in silt because of flooding.

Some of the flats were too wet to get on with a tractor so they’ve been successfully resown with ryegrass and white clover by using a helicopter.

Don’s thoughts are that the 75ha of ryegrass-white clover pasture will be included in a three-year rotation involving pasja, followed by two years of a high-performing ryegrass-white clover sward.

“Because we are unfamiliar with these new species we are on a very steep learning curve and a lot of trial and error will be involved in determining the appropriate management for them,” Don says.

“Our intention is to start lambing twinbearing-older ewes (in-lamb to Primera sires) on the ryegrass-white clover paddocks in late August. From here they can be moved on to the plantain and red clover swards.”

As growth rates increase within the swards, ewes and lambs and yearling cattle will be pulled off the hills to control the feed on the flats. Once weaning takes place the flats will be stocked almost entirely with lambs and cattle.

“Last year was our first full year using irrigation and it worked very well.”

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Three of the Polsons’ employees, from left: Hoani Pouwhare- Anderson, Kapawai and Jason Anderson. Front: Jason Anderson’s son Jayna.

While Don and Liz oversee the business and are both actively involved in it, the three farms each have a manager – Waipuna is managed by Roy Pullen, Te Tui by Gerald van der Vlerk and Awarua by Andrew von Pein.

“We are very appreciative of our managers and our three other employees: Jason Anderson, Hoani Pouwhare- Anderson and Kapaiwai. They have all been through the highs and lows of floods and droughts and are still with us,” Don says.

“Farming has become more high-tech with animal recording, irrigation and modern machinery and they have all coped with these with ease, which has amazed us.”

Pasture renewal

As part of a pasture renewal programme to replace poor performing pastures and to eliminate persistent weeds like Californian thistles, the Polsons grow 80ha of turnips for summer feed.

Turnips are grown instead of other summer forage crops because they produce a bulk of feed in February when it is required.

“Other crops are often ready to graze earlier than we require them,” Don Polson says.

“Also, turnip bulbs don’t deteriorate when it is very dry. They have real value in a drought.”

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The Polson’s winter 12,000 ewes of which 10,300 are mostly commercial Highlander ewes.

The Polson’s business winters 12,000 ewes. Of these 10,300 are mostly commercial Highlander ewes – 6300 are mated to Highlander ram hoggets and 4000 to Primera ram hoggets.

The remaining ewes include 1000 Multiplier Primera ewes mated to elite two-tooth progeny-tested Primera rams and 700 elite Highlander ewes mated to elite two-tooth and hogget rams with a strong facial eczema-tolerant background.

High lambing percentages are maintained without flushing ewes before mating. All ewes are mated on the hills except for the Highlander DNA ewes.

“We are comfortable with our current docking percentage of 150%. A greater number of lambs challenges our ability to finish them and we must remain flexible. Who knows what the future holds,” Don Polson says.

About 3000 ewe hoggets are lambed each year, producing about 2900 lambs. Initial selection for those going to the ram is made on liveweight assessment at the drafting gate.

The second stage of selection is based on those that conceive, normally about 90%.

They are mated to Primera ram hoggets. Ewes are scanned to identify the multiple-bearers and lambing starts in late August.

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Ewe shearing at Waipuna.

A number of the multiplebearing Highlander ewes mated to Primera rams are lambed in late August on the easy country as are the Highlander DNA ewes and Multiplier Primera ewes.

The ewe flock docks on average 18,000 lambs of which 12,000-13,000 are finished at an average slaughter weight of 18kg. All lambs are processed by Silver Fern Farms.

About 4000 Highlander ewe lambs are retained for breeding within the business and a further 1500 sold to commercial farmers for breeding.

Selection of these lambs must be made early enough so that commercial clients can get them up to 40kg for mating as hoggets. Usually this occurs in January at an average weight of 25kg.

“A 25kg lamb in January should easily be able to reach 40kg by mating,” Donsays.

A number of Primera ram hoggets are also sold for breeding. Having to delay selection of ram hoggets for sale-breeding until they are able to be assessed in February for structural faults is a further impediment to management.

“Under normal commercial farming practice most of the 1300 ram hoggets culled in the assessment process would have been killed a lot earlier if we did not have to wait to go through that process. There are significant costs associated with this.”

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The Polsons run 500 Stabiliser breeding cows primarily to maintain feed quality.

The Polsons’ business also runs 500 Stabiliser breeding cows over the three farms primarily to maintain feed quality. However, some of the country is too steep to run cattle.

“We don’t do our cattle as well as we would like,” Don says.

“Their value is in maintaining feed quality. Sheep are our first priority.”

Cows are calved from mid-October to mid-November on the easier hills and achieve an average calving percentage in excess of 90%.

About 130 two-year-old heifers are calved behind an electric fence on Awarua, generally producing about 125 calves.

“We’ve had mixed results with our two-year-old calving. We have learnt that manipulating their condition score tends to lead to calving problems so we try and maintain it at the same level throughout pregnancy.”

Calves are yard weaned in early April.

Don and Liz Polson own two farms, Waipuna and Te Tui and part-own a third, Awarua, in partnership with David Boswell. Te Tui is a 600ha farm of mixed contour – 100ha cultivable, 200ha easy ash-covered hills and 260ha steeper papa hills – on Fields Track Rd off SH4 north of Waipuna. Awarua is a 512ha farm – 160ha of cultivable ash soil, 305ha of papa and ash soil and 47ha of pine forest and bush – at Raetihi in the central North Island. This property’s climate is quite different to the other two farms – it’s significantly higher in altitude with a shorter growing season and is less prone to dry summers.

“Early yard weaning has been very successful for us. We shut the calves in the yards for three days and feed them balage and grain,” Don says.

“They then go out on to the flats where they continue to have access to grain up to a maximum of one kilogram a head per day and poorer-quality pasture which exists on the flats at this time of the year. They do really well and become our best friends.”

This feeding regime continues as long as grass is in short supply. They remain on the flats until late July when they are set stocked on the hills for two months then brought back on to the flats for growing out.

The best 100 yearling steers are sent up to Awarua in early December and finished as two-and-a-half-year olds at about 300kg carcaseweight.

The rest are finished at Waipuna. Replacement R1 heifers are sent to Te Tui and the culls are finished or sold store at Waipuna.

“Cattle are our safety valve. Sometimes we will even graze them off the farm if we consider it appropriate.”

The Polsons’ business is a complex one involving not only commercial sheep and cattle breeding and finishing enterprises but also ram breeding.

They are a genetic breeding partner for Focus Genetics, producing Highlander and Primera rams and ram hoggets.

Such complexity with so many different stock classes and breeds is a big impediment to management although having three separate farms does enable some rationalisation.

Te Tui runs the Highlander Multiplier breeding ewes, 150 Stabiliser breeding cows and 150 replacement R1 Stabiliser breeding heifers. Most male lambs bred onfarm are finished on Te Tui.

Waipuna is home to the main breeding ewe flock as well as the Highlander DNA ewes and Primera Multiplier ewes. It also finishes the Awarua-born lambs and the surplus lambs from Te Tui. As well as running most of the lambs,

Waipuna carries 200 breeding cows, all the R1 steers, some R2 steers and heifers for finishing and all the R1 heifers not required as replacements.

Awarua’s main function is to run the in-lamb hoggets and in-calf R2 heifers as well as finish some of the R2 steers. A lot of the hills on the farm lie to the north providing excellent shelter for lambing hoggets.

Steeped in erosion

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Slip damage on Waipuna from last year’s wet winter.

The Polson’s farming business has been severely disrupted by two big weather events in the past 12 years – the 2004 flooding that devastated parts of the lower North Island and last year’s extremely wet winter.

Both events caused major erosion on the hills and flooding-silting of the river flats. Don Polson believes that if farming is to continue sustainably on steep hill country the erosion problem must be addressed.

He believes that blanket-planting of shortrotation trees is not the answer because of accessibility and the post-harvest trash problem.

“We must continue to be able to graze our hills using wide-spaced planting of long-rotation trees like poplars. They not only provide ground stability but also stock shade, valuable fodder during droughts and are aesthetically pleasing.

“The latter is particularly important for our burgeoning tourist industry. It is likely farmers will not be able to finance the level of planting required therefore they would need to be rewarded for fixing carbon.

“With the rapidly evolving drone technology we should in the near future be able to assess the amount of carbon being fixed from the air,” he says.

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Don Polson surveys the flood damage on his irrigated flats.

The Polson family name was established in the Wanganui area in 1873 when Don Polson’s great grandfather Donald Gunn Polson bought Manurewa, a 460ha farm at the southern end of what is now known as Waipuna.

Further land was subsequently bought by Donald until Don’s grandfather, Sir William John Polson, took over the farm. It underwent a period of consolidation under his ownership because of his divided interest in politics.

Sir William was an independent Member of Parliament for Stratford and leader of the Upper House before it was disbanded. He was also a foundation member of the NZ Farmers’ Union (now Federated Farmers) and its president for 18 years.

“The organisation had a lot of political clout in those days. It almost ran the country,” Don says.

Don’s father and uncle subsequently managed the property and when they returned from World War II the farm was divided three ways, the third-share going to their sister Dorothy.

When Don and his late brother Alistair – a past national president of Federated Farmers and a special agricultural trade envoy for NZ – were handed the reins of their father’s share of the farm they set about amalgamating, with the help of their cousin Sam, the farms previously owned by Sir William.

Sam’s father, John Polson, was also politically inclined, serving on the NZ Meat Board. In 2005 Don and Alistair decided to follow the family tradition and divide the business so the farm was once again split.

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