Here is our final report. Beyond the numbers from the organic and conventional vineyards, we believe this is one of the best practical resources available on how to convert a vineyard to organic management, and what can happen along the way. Please share it widely!
You can download the full report HERE.
Printed copies of the report are available free of charge to all members of the New Zealand wine industry. Email firstname.lastname@example.org to request a copy.
Summary of Results
The three focus vineyards showed that each vineyard’s pathway into organic production is unique. Organic vineyard managers must respond adaptively to the needs of their own sites and vines. Nevertheless, some common themes emerged.
Pests and Disease
Pest and disease levels were generally low on the focus vineyards. Even in seasons with high disease pressure, the organic spray programmes were thoroughly effective. Organic pest and disease control costs were lower than conventional costs at two of the three focus vineyards.
For most soil variables, no statistically significant trends were detected related to the change to organic management. All three organic vineyards showed a reduction in soil compaction undervine, and a corresponding increase in water infiltration. On the one hilly site, the Central Otago focus vineyard, the organic block showed a reduction in soil erosion compared with the conventional block.
Weed management proved one of the most significant technical challenges for all three organic vineyards. However, all vineyard managers believed that they had achieved good weed control on the organic blocks. All three vineyards used undervine cultivation for their organic weed management. Organic weed control costs were higher than conventional costs at all sites.
The one exception to this was a block of Pinot Noir at Wither Hills, which struggled with yields and vigour once converted to organic management. Managers suspected that the vines were stressed by having their surface roots cut by undervine cultivation. The young age of the vines, the compacted soils and the rootstock all would have made these vines’ root systems vulnerable to disturbance. By the end of the trial, following intensive soil management efforts, the vines showed signs of recovery.
Production costs were specific to individual vineyards and their management practices. At Mission Estate, organic production costs were lower than conventional costs. At the other two vineyards, organic production costs were higher than conventional costs.
Laboratory assays did not reveal any major chemical differences between organic and conventional juice and wine samples.
At Mission Estate, the winemaker found the organic wine to be of higher quality. At the other two focus vineyards, vineyard variables made the wines difficult to compare directly, and winemakers therefore were hesitant to select either the organic or conventional wines as their favourites.
At the end of the project, all three wineries chose to either maintain or expand their certified organic growing areas.
For more detail, download the full report (4MB PDF).