Luke Johnston - Organic Viticulture: why research needs to progress grower practices
How it all started
After working at Castagna and Sorrenberg vineyards (both biodynamic) in Beechworth, and reviewing the relevant literature for two minor university research projects, I realised that many questions regarding the organic system remain unanswered.
To my surprise, and many of the academics, there is in fact a strong body of knowledge on organic and even biodynamic practices. Most of these peer reviewed studies have focused on measuring soil properties, in particular soil biological characteristics. However, little research has been done on grapevines, and nothing in Australia.
Dr Cassandra Collins from The University of Adelaide encouraged me to develop a potential Ph.D experiment. Mind you, there were a few raised eyebrows from some at the university when biodynamics was mentioned! Nonetheless, the industry support was unquestionable, and a trial at Gemtree Vineyards in McLaren Vale was established.
The scientific experiment
There are two main methodologies for conducting organic scientific research: 'research trials' and 'comparative surveys'. Therefore, in order to adequately measure the effects of using organic viticultural techniques, both methodologies will be used.
Comparative soil survey
In spring 2009, we intend to conduct a soil survey by measuring the soil physical, chemical and biological properties of 10 established organic/biodynamic vineyards and their adjacent conventional neighbours. We have some sites earmarked, however, more sites are needed. If you have been using organic/biodynamic practices for at least 7 years, and your neighbour are keen to partake please email me. luke.johnston@adelaide.edu.au.
This study will be used to gauge and the longer term effects of organic/biodynamic practices over various soil types and regions. While there are now a few examples of such studies in Germany, South African and Greece nothing of the like has been conducted on Australian vineyards and is long overdue.
McLaren Vale vineyard 'conversion' trial
Beginning in July 2008, a 10ha section of the Gemtree vineyard (which was traditionally managed using a low input conventional system) was divided into four management systems (organic, biodynamic, low input conventional and traditional conventional) each replicated four times. As noted in the literature, organic growers often have better soil physical and biological properties than conventional growers, potentially from the use of compost compared to synthetic fertiliser. In order to separate the effects of compost from 'the system' per se, each treatment will be divided into with and without compost.
This trial will run for 3 years and therefore we will be able to evaluate what changes to the soil properties, one can expect over the conversion period. Other measurements include, grapevine physiological and reproductive growth, grape berry parameters and a sensory evaluation of wines made under each system will be undertaken. Finally a financial analysis of the four systems will be done to advise growers on the costs involved in using each management system.
Finally…
Unlike most PhD studies, this is a holistic study. Therefore, in order to specialise in such a diverse range of fields, I need supervisors with a wide breadth of knowledge. I am indebted to Dr Cassandra Collins (vine physiologist), Dr Petra Marschner (soil microbiologist) and Mr Chris Penfold (cover crop/under vine management) for their many hours of conversations and corrections.
Although we have no results at this stage, and we can't predict what we will find in the future, the literature review has demonstrated to many at an academic level that many components of the organic system are scientifically sound. I am hopeful that this research will once again advance grower management practices.