Winepress - July 2024

Pick of the posts

Steel, wood, recycled plastic or a combination are on offer to replace broken vineyard posts. But which choice is the best for your vineyard?

BEV DOOLE

THE LONG walk down vineyard rows to stop and check every wooden post for cracks or breakages is well under way. It’s time consuming and labour intensive and with estimates of more than 600,000 posts in Marlborough to be replaced and disposed of each year there’s also a significant cost to winegrowers.

This year’s drought hasn’t helped. “Some vineyards have had a 50% increase in breakages compared to 2023 because the dry season means there’s less give in the ground when the machinery goes through,” says Kerry Hammond, viticulturist for Sheridan Contracting.

Wooden posts are treated with a preservative containing copper, chromium and arsenic (CCA), which makes disposal difficult when they break or come to the end of life. For many years broken posts were stockpiled on vineyards, waiting for a solution to emerge. Marlborough company Repost have became part of that solution with their operation to trim up broken posts and sell for farm fencing. Repost charges the vineyard up to $2 a post –less than the cost of sending it to landfill – but 5-10% still goes to landfill as off-cuts.

“There’s definitely a growing understanding about moving away from CCA-treated posts for environmental and cost reasons,” says Kerry. “It’s about $55 to put in a replacement wooden post – buying it, paying labour to remove the old one, put in the new one, and dispose of the old post. And there’s still the risk of breakage.” He estimates about 40% of replacement posts being installed by Sheridan Contracting are alternatives. It’s creating a patchwork in vineyards as wooden posts are replaced by metal or plastic and is helping the NZ wine industry reach its goal of zero waste to landfill by 2050.

Dr Ed Massey, NZ Winegrowers general manager sustainability, says there’s a lot to weigh up when it comes to alternative vineyard posts. “The NZW environment

strategy has six focus areas: waste, climate change, plant protection, soil, water and people. Business decisions might have positive impacts in one of those focus areas but less positive impacts on another.

“If you took a solely climate-change based approach, wooden posts would be a good option because wood is a really good carbon store. However if you took a waste focus, it’s a different story. Treated wooden posts are more difficult to consider at the end of life,” says Ed. “Steel posts don’t break, they’re potentially recyclable but from a climatechange point of view they’re emissions-heavy to produce and recycle. Plastic posts are great for turning waste plastic into a valuable resource but they don’t have the carbonstorage benefits of wood.”

Decisions around vineyard posts involve weighing up environmental, financial and safety considerations. However, whatever decision is made in the vineyard also needs to consider the growing demand from the market for environmental accountability including reduced carbon emissions, reduced chemical use and zero waste to landfill. “There’s no silver bullet when it comes to finding the ideal vineyard post,” says Ed. “They all have their pros and cons and it’s important that growers consider all the information before deciding what’s right for them.”

So what are the options on the market?

Steel posts

Steel is gaining popularity as a replacement for broken wooden posts because it is stronger, lighter and easier to handle through the wires and canes of the vineyard.

Tracey Marshall, Sustainability Manager for Pernod Ricard Winemakers NZ, says weight was a key factor for the company when choosing to replace treated wood with Eco Trellis steel posts. “While other alternatives to CCA posts are available, their weight is a primary concern. Manual handling is the second highest contributor to lost time accidents, and our goal is zero harm,” says Tracey. Steel posts were also preferred after assessing overall environmental impact, including disposing of CCA-treated posts and working towards zero waste to landfill. “The only negative impact compared to treated wood are the higher carbon emissions to manufacture and recycle steel,” says Tracey. “The strength and consistency of steel is another benefit, especially with increasing automation in the vineyard.”

Steel repair kit

Ocloc V is a steel repair kit that prolongs the life of a damaged wooden post. The 1.05m galvanised stake is rammed down alongside the post and then screwed on to provide ongoing support, like a splint on a broken leg. Made in Australia, Ocloc V is new to Marlborough but early adopters praise the cost, time and environmental advantages of repairing, rather than replacing. HFT Vineyards owner Chris Hammond is trying Ocloc out for the first time this winter. “I was looking for a solution to my pile of broken posts getting bigger and bigger. Ocloc is much cheaper and quicker than putting in a new wooden post. I’ve repaired 700 posts and am impressed so far - we use a hand-held post rammer and it only takes about three minutes per post. We’ve put it on cracked posts as well as ones that are broken above the ground, as long as the edges can knit together.”

Plastic posts

Diverting irrigation pipe and plastic grow guards away from landfill and turning them into vineyard posts is a strong selling point for Future Post. The plastic posts, made in Blenheim, are described as “awesome” by Mark Lucas, solid waste manager for Marlborough District Council. “My job is to keep stuff out of landfill. Future Post is solving two big issues for me – they’re recycling soft and hard plastic as well as providing an alternative to treated wooden posts.” Jeremy Dennis, Utawai vineyard manager, has been replacing broken wooden posts with Future Post for about four years. “It does what I want a post to do – they don’t break, the round shape means there’s always an outside edge to put clips in, and the nails and clips don’t fall out the way they do with wooden posts. Future Post is heavier than wood, but we manage with a post driver on the back of the tractor.” Jeremy is used to the posts flexing in hot sun until the plastic has hardened off. “It’s never been a problem for vineyard work. The posts keep their strength, we’ve had no breakages and it’s great to be reusing plastic instead of dumping it.”

Untreated wood coated with plastic

Australian company Woodshield has been supplying Marlborough vineyards for nearly 20 years with untreated timber posts encased in a coating of recycled plastic. Nigel Sowman, viticulturist at Dog Point Vineyard, says it’s a good option for their organic vineyards as they work to replace chemically treated wooden posts. “Our vineyards are quite old and we have a multitude of different trellising configurations. Woodshield is much lighter and easier to handle than a CCA-treated post. It fits into an established trellis and best of all we can put nails and staples in where suits us. We’re getting the strength of wood without the chemical treatment, they store carbon, and the plastic is made of recycled irrigation pipe. The main downside is the posts don’t have a pointy end but they slot in easily where there’s already a hole in the ground and they’re lasting well.” When it comes to end of life, the plastic outer can be peeled off and recycled, while the wooden core is reusable as chipped-up mulch, firewood or biochar.

CCA treated wood

Treated wooden posts are the backbone of the Marlborough wine industry – they were the first to be used and are still prevalent throughout vineyards, old and new. Radiata pine is grown and milled in the top of the South and provides an ongoing carbon store as vineyard posts. A key issue is disposing of broken posts. Repost’s work to turn them into fence posts is making a difference but those that end up in landfill take up a lot of space because they can’t be compacted. Once the post finally breaks down, the CCA is confined in the fully lined landfill but Council is charged for greenhouse gas emissions as the post decomposes. “We are trying to cut down on everything going into landfill because new landfill space is very expensive to build,” says Mark Lucas. “There is potential for energy plants to burn treated wood or use it as biofuel instead of coal but we haven’t got there yet in Marlborough.”

In the meantime, grower and vineyard consultant Dominic Pecchenino is sticking with wood for replacement posts: “The half round CCA-treated post is doing the job for us – it’s what we’ve had from the start and keeps us uniform and consistent. My broken posts get a second life for fencing on farms.”