Monday, 25 May 2015 14:56

Organic Focus Review

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Soil scientist Tim Jenkins measures water infiltration at Wither Hills. Soil scientist Tim Jenkins measures water infiltration at Wither Hills.

To go organic, what should I do first? Is it possible on every vineyard? What does it cost? What will happen to my yields?

After receiving questions like these from curious grape growers for some years, Organic Winegrowers New Zealand knew that it was time for the Organic Focus Vineyard project. 

In the 2011-12 growing season, with funding from the MPI Sustainable Farming Fund and New Zealand Winegrowers, we began the project. Three vineyards, each in a different region, began conversion to organic management. Half of each vineyard would be left under non-organic management for comparison. 

The focus vineyard managers expressed a variety of reasons for getting involved with the project, including a desire to learn how to take optimum care of their land and vines, and to produce premium quality wines. 

The vineyard managers bravely agreed to be subjected to intense scrutiny. Scientific technicians would monitor their soils, pest and disease levels, irrigation and more. The vineyard managers themselves would keep detailed field observations and yield records, as well as tracking every vineyard financial cost. At the end of the three-year organic conversion period, we’d compare the resulting wines as well. 

To ease the transition, we supplied the vineyard managers with free advice from organic viticultural consultant Bart Arnst throughout the project.

We knew from the outset that this was a demonstration project aimed at conveying best practices to others in the industry, rather than a traditional scientific project. Three vineyards would never prove, once and for all, the relative merits of organic vs. conventional wine production. Still, core lessons emerged across the focus vineyards, with deep relevance for other grape growers considering the organic transition.

1.Organic pest and disease management methods are robust.

All of the vineyard managers were highly satisfied with the level of control they received using organic canopy sprays, with Bart Arnst’s advice on timing and application. In all three years of the trial – including a few seasons with high disease pressure – the organic vineyards had little to no crop loss from pests and diseases. 

2. Consider undervine management carefully.

All of the focus vineyard managers agreed that undervine weeding presented their biggest learning curve. Undervine cultivation, the selected tactic for all three organic focus blocks, needs careful planning, with attention to weather, soil type and vine development.

Still, some fears of cultivation proved unfounded. In Central Otago, some local growers had expressed scepticism about cultivation, fearing erosion of the region’s fragile soils. However, Gibbston Valley Wines’ organic focus block in Bendigo showed the opposite to be the case. In fact, water infiltration increased in the organic blocks once cultivation had opened the soil surface under the vines; meanwhile, water tended to run straight off of the hardened herbicide strip under the conventional vines. This was confirmed by both manager observations and scientific field measurements.

3. Understanding your soils, and your vines’ relationship to them, is essential to organic management.

The Wither Hills vineyard managers, in their final reflections on the project, put it this way: “Vine health is often masked by the plethora of chemicals and fertilisers available. Once these are taken from the equation, the viticulturist has to better examine what is happening below the ground.”

Of the six blocks in the trial (two grape varieties in each of three regions), only one saw a significant loss in yields under organic management: the Wither Hills Pinot Noir. The reasons likely were buried underground. The organic Pinot’s combination of young vine age and highly compacted soils due to past horticultural use meant that the vines’ shallow root systems were not well positioned to handle undervine cultivation. 

Of course, soil health can be improved – and the vines respond. Wither Hills’ organic Pinot was showing signs of recovery by year three, after a programme of deep ripping to break up soil compaction; sowing interrow crops to boost organic matter levels; and applying organic nutrients. It became a teachable moment for the local industry: before converting to organic management, consider the history of your vines, and think about how you can support them through the organic transition. 

The nearby vines of the Wither Hills Sauvignon Blanc continued to yield well under organic management. 

Meanwhile, other blocks experienced no such difficulties. At the Hawke’s Bay focus vineyard, on Mission Estate’s Mere Road vineyard, the Merlot and Syrah both had comparable vigour, yields and operating costs across the organic and conventional systems in all three years of the trial – delighting the vineyard and winery staff with the gracefulness of the transition and the quality of the organic fruit.

4. Warning: organic growing can be addictive. 

Perhaps one of the most interesting data points from the trial was what the participating wineries decided to do once the project finished. All of the vineyard managers expressed a passion for organic growing by the end of the three years. Two of the wineries involved, Mission Estate and Gibbston Valley Wines, decided to expand their commitments to organic growing. Wither Hills chose to maintain the organic/conventional split, integrated into the company’s existing patchwork of organic and conventional vineyards. Gibbston Valley began converting more land to organic management. 

Asked for final advice to prospective organic growers, Ben Burridge, focus vineyard manager at Wither Hills, offered: “Start small so you can gain knowledge about what processes are required to run an organic vineyard. The Organic Focus Vineyard Project has demonstrated that organic blocks are managed quite differently depending on location, variety and philosophy.”

The project “really just cemented the fact that it is reasonably simple to convert to organic production here in Central Otago, provided one has the desire to do so, along with the required financial resources for the change,” reflected focus block manager Grant Rolston of Vinewise Viticulture. As advice for others contemplating the organic conversion process, he added: “Don’t be afraid of taking a step back so that you may be allowed to go forward.”

A full report from the project, complete with data and detailed vineyard manager observations and advice, will be mailed to all New Zealand Winegrowers members this autumn. Blogs featuring three years of vineyard manager experiences and observations are at, and will remain online as a lasting resource for others considering organic conversion.


The project team is grateful to the Sustainable Farming Fund and New Zealand Winegrowers for their funding support, as well as our field day sponsors (AgriSea, BioAg and BotryZen) and our in-kind service sponsors (BioGro, Hill Laboratories, HydroServices, Soil Foodweb New Zealand). We also thank our diligent data collection and analysis team, including Fruition Horticulture, Tim Jenkins, Kirstin Creasy and Anna Lambourne; and the focus vineyard wineries and staff for their huge contribution of time, energy and enthusiasm.

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