NZ-grown eucalypt vineyard posts offer alternative to pine
The pine posts used to support grapevines in New Zealand vineyards have a couple of weaknesses; they break easily and are treated with toxic copper chromium arsenic (CCA). These chemical treatments may leach into the soil and water which is bad for the image of the industry. Also, environmentally acceptable disposal of the posts is difficult.
These problems are creating an interest in ground durable alternatives for vineyard posts, including eucalypts (gum trees).
Eucalypts are well-adapted to low altitude, sheltered coastal areas of New Zealand, generally requiring sheltered sites, fertile and well-drained soils and a mild winter. Some species require regular annual rainfall while others are adapted to low rainfall areas including Southern Marlborough.
Vineyard Timbers Limited
Vineyard Timbers Ltd is promoting the establishment of eucalypt hardwood forests to produce naturally durable timber for New Zealands wine industry and other uses where high strength is required.
It will be many years until significant volumes of eucalypt timber come on stream, says Vineyard Timbers Limited director (and environmental forestry consultant), Paul Millen. Meanwhile, the company is selling small volumes of eucalypt vineyard posts sawn from older farm forestry eucalypt plantations in Marlborough and elsewhere.
New Zealand Drylands Forestry Initiative
With support from Scion (previously the Forest Research Institute), Paul has identified several eucalypt species and provenances selected as suitable for ground-durable uses including vineyard posts. These are now being trialed at several Marlborough sites, with support from the Marlborough District Council, Proseed NZ Ltd and local landowners.
The next step is to explore the eucalypts forestry and woodlot potential for East Coast dryland regions including Marlborough, which are becoming increasingly drought-prone. Farming incomes could become even more tenuous and options more limited, as a result of climate change.
Two species showing up as as suited to drylands plantings and with post-wood potential are Eucalyptus bosistoana and E. cladocalyx.
Paul is developing a research project with the School of Forestry in Canterbury, to look more closely at the growing of drought-tolerant eucalypt species as a diversification option. This New Zealand Drylands Forestry Initiative will seek funds from the Ministry of Agriculture and Forestrys Sustainable Farming Fund, to establish large-scale breeding populations of selected species,
The focus is identifying timber species adapted to dryland areas, developing suitable planting stock, designing sustainable production systems and investigating potential costs and returns from timber and carbon sequestration.
Eucalypts at Marlborough Ridge
John and Robyn Cuddon are among a small number of Marlborough landowners who have participated in the early eucalypt trials, planting almost 2000 trees representing 20 species at Marlborough Ridge, near Blenheim. Most have done well and another planting is planned.
The aim is to plant intensive mixed species pockets, as finances permit.
Grapegrowers themselves, the Cuddons are interested in alternatives to CCA-treated posts. Another positive is the attractiveness of eucalypts, which are being made a feature of the property and an adjoining subdivision, developed by the couple. Also, they can be used to control erosion. Our only reservation is susceptibility to fire, says Robyn.
Eucalypts for vineyard posts
Vineyard posts are treated with toxic CCA (copper chromium arsenic) which stops the pine softwood rotting in the ground. This has a couple of downsides; the possibility of the toxins leaking into the soil or groundwater, and disposal.
Between 74,200 and 572,400 treated pine posts are broken in Marlboroughs 21,200 hectares of vineyard each harvest. This is based on a breakage rates of 3.5/ha (Marlborough District Council estimate) to 27/ha (Paul Millens figure, based on the 5% often quoted in the industry).
Demand for freebie damaged posts for uses including fencing on West Coast dairy conversions has recycled a portion of this waste-stream. However, massive expansion of vineyard area means vineyard stockpiles are slowly but surely growing.
Broken posts cant be burned or buried as this would release toxins into the air or soil. One disposal option is the Blenheim landfill, at a cost of $21/ m3. With around 20 posts making up a cubic metre, if all waste posts were taken to the landfill of they would take up 3710-28,620m3; 2.5 to 20% of its 150,000m3 annual capacity.
There is growing concern that using CCA-treated posts is not a good look for New Zealand vineyards, creating an interest in ground durable alternatives including eucalypt.
There is very little locally grown eucalpyt available in New Zealand. Paul is hoping to change this through the New Zealand Drylands Forest Initiative which he hopes will see farms grow eucalypt timber for nearby vineyards, with a considerable saving in costs and energy. Thinnings could be especially suitable for use as vineyard posts.
Another option would be for wine companies to establish on-site eucalypt plantings. Ten to 15% of the capital cost of new planting and replanting of vineyards is tied up in posts, says Paul so growing their own would make business sense.
Eucalypts at Seresin Estate
Organic certifier, Bio-Gro, stipulates that when posts are broken they must be replaced with non-treated alternatives.
Marlborough organic-certified vineyard, Seresin Estate, last year bought 100 ground-durable eucalypt posts from Vineyard Timbers Limited, to replace broken posts. Eucalypt stakes and poles are also being used in the companys orchard and olive groves.
Seresin planted an area of eucalypts with the intention that they be encouraged to coppice then used as posts. These were accidentally sprayed and wont be replaced, as Colin has since become concerned about the possibility of eucalypt flavours tainting wines, if they are grown too close to vines.
The company has chosen to use wooden posts ahead of other pine post alternatives, mainly for their natural appearance.
Before moving to Marlborough two years ago, Colin worked for a wine company in the Margaret River, 300 kilometres south of Perth. A lot of vineyards there were moving away from treated pine posts to alternatives. However, eucalypt was in increasingly short supply because of a growing feeling that this native species should be protected. Pauls idea of farming eucalypts for specialist uses including vineyard posts is ground-breaking stuff.
Trials in Australia had highlighted soil contamination under piles of treated posts, leading to recommendations that they be wrapped or stored in sheds.
Eucalypts for timber
Eucalypts grow fast in New Zealand, with the potential for short rotations of 20 to 25 years for sawlogs compared with 30 years for pine plantations. Pole crops could be harvested in less than 10 years. Many eucalypts coppice after cutting so offer the potential for several rotations without soil erosion or replanting costs.
Eucalypt is a potentially valuable timber which could replace imported hardwoods such as non-sustainable teak and kwila. In 2007, 26,000 m3 of hardwood was imported at a total cost of $32 million ($1230/m3) for uses including marine grade decking, cross arms for the electrical lines industry and rail sleepers.
The current domestic retail value of CCA treated sawn timber is $800-$900 per m3. There are also export opportunities due to shortages in the supply of naturally durable timbers in Australia due to public pressure to stop logging native eucalypt forests.
These problems are creating an interest in ground durable alternatives for vineyard posts, including eucalypts (gum trees).
Eucalypts are well-adapted to low altitude, sheltered coastal areas of New Zealand, generally requiring sheltered sites, fertile and well-drained soils and a mild winter. Some species require regular annual rainfall while others are adapted to low rainfall areas including Southern Marlborough.
Vineyard Timbers Limited
Vineyard Timbers Ltd is promoting the establishment of eucalypt hardwood forests to produce naturally durable timber for New Zealands wine industry and other uses where high strength is required.
It will be many years until significant volumes of eucalypt timber come on stream, says Vineyard Timbers Limited director (and environmental forestry consultant), Paul Millen. Meanwhile, the company is selling small volumes of eucalypt vineyard posts sawn from older farm forestry eucalypt plantations in Marlborough and elsewhere.
New Zealand Drylands Forestry Initiative
With support from Scion (previously the Forest Research Institute), Paul has identified several eucalypt species and provenances selected as suitable for ground-durable uses including vineyard posts. These are now being trialed at several Marlborough sites, with support from the Marlborough District Council, Proseed NZ Ltd and local landowners.
The next step is to explore the eucalypts forestry and woodlot potential for East Coast dryland regions including Marlborough, which are becoming increasingly drought-prone. Farming incomes could become even more tenuous and options more limited, as a result of climate change.
Two species showing up as as suited to drylands plantings and with post-wood potential are Eucalyptus bosistoana and E. cladocalyx.
Paul is developing a research project with the School of Forestry in Canterbury, to look more closely at the growing of drought-tolerant eucalypt species as a diversification option. This New Zealand Drylands Forestry Initiative will seek funds from the Ministry of Agriculture and Forestrys Sustainable Farming Fund, to establish large-scale breeding populations of selected species,
The focus is identifying timber species adapted to dryland areas, developing suitable planting stock, designing sustainable production systems and investigating potential costs and returns from timber and carbon sequestration.
Eucalypts at Marlborough Ridge
John and Robyn Cuddon are among a small number of Marlborough landowners who have participated in the early eucalypt trials, planting almost 2000 trees representing 20 species at Marlborough Ridge, near Blenheim. Most have done well and another planting is planned.
The aim is to plant intensive mixed species pockets, as finances permit.
Grapegrowers themselves, the Cuddons are interested in alternatives to CCA-treated posts. Another positive is the attractiveness of eucalypts, which are being made a feature of the property and an adjoining subdivision, developed by the couple. Also, they can be used to control erosion. Our only reservation is susceptibility to fire, says Robyn.
Eucalypts for vineyard posts
Vineyard posts are treated with toxic CCA (copper chromium arsenic) which stops the pine softwood rotting in the ground. This has a couple of downsides; the possibility of the toxins leaking into the soil or groundwater, and disposal.
Between 74,200 and 572,400 treated pine posts are broken in Marlboroughs 21,200 hectares of vineyard each harvest. This is based on a breakage rates of 3.5/ha (Marlborough District Council estimate) to 27/ha (Paul Millens figure, based on the 5% often quoted in the industry).
Demand for freebie damaged posts for uses including fencing on West Coast dairy conversions has recycled a portion of this waste-stream. However, massive expansion of vineyard area means vineyard stockpiles are slowly but surely growing.
Broken posts cant be burned or buried as this would release toxins into the air or soil. One disposal option is the Blenheim landfill, at a cost of $21/ m3. With around 20 posts making up a cubic metre, if all waste posts were taken to the landfill of they would take up 3710-28,620m3; 2.5 to 20% of its 150,000m3 annual capacity.
There is growing concern that using CCA-treated posts is not a good look for New Zealand vineyards, creating an interest in ground durable alternatives including eucalypt.
There is very little locally grown eucalpyt available in New Zealand. Paul is hoping to change this through the New Zealand Drylands Forest Initiative which he hopes will see farms grow eucalypt timber for nearby vineyards, with a considerable saving in costs and energy. Thinnings could be especially suitable for use as vineyard posts.
Another option would be for wine companies to establish on-site eucalypt plantings. Ten to 15% of the capital cost of new planting and replanting of vineyards is tied up in posts, says Paul so growing their own would make business sense.
Eucalypts at Seresin Estate
Organic certifier, Bio-Gro, stipulates that when posts are broken they must be replaced with non-treated alternatives.
Marlborough organic-certified vineyard, Seresin Estate, last year bought 100 ground-durable eucalypt posts from Vineyard Timbers Limited, to replace broken posts. Eucalypt stakes and poles are also being used in the companys orchard and olive groves.
Seresin planted an area of eucalypts with the intention that they be encouraged to coppice then used as posts. These were accidentally sprayed and wont be replaced, as Colin has since become concerned about the possibility of eucalypt flavours tainting wines, if they are grown too close to vines.
The company has chosen to use wooden posts ahead of other pine post alternatives, mainly for their natural appearance.
Before moving to Marlborough two years ago, Colin worked for a wine company in the Margaret River, 300 kilometres south of Perth. A lot of vineyards there were moving away from treated pine posts to alternatives. However, eucalypt was in increasingly short supply because of a growing feeling that this native species should be protected. Pauls idea of farming eucalypts for specialist uses including vineyard posts is ground-breaking stuff.
Trials in Australia had highlighted soil contamination under piles of treated posts, leading to recommendations that they be wrapped or stored in sheds.
Eucalypts for timber
Eucalypts grow fast in New Zealand, with the potential for short rotations of 20 to 25 years for sawlogs compared with 30 years for pine plantations. Pole crops could be harvested in less than 10 years. Many eucalypts coppice after cutting so offer the potential for several rotations without soil erosion or replanting costs.
Eucalypt is a potentially valuable timber which could replace imported hardwoods such as non-sustainable teak and kwila. In 2007, 26,000 m3 of hardwood was imported at a total cost of $32 million ($1230/m3) for uses including marine grade decking, cross arms for the electrical lines industry and rail sleepers.
The current domestic retail value of CCA treated sawn timber is $800-$900 per m3. There are also export opportunities due to shortages in the supply of naturally durable timbers in Australia due to public pressure to stop logging native eucalypt forests.