Professor Robert White is Emeritus at the Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Australia. His long experience has made him one of the most important soil scientists internationally. He is the author of several books used as textbooks in many universities worldwide. Among these, Professor White is the author of “Principles and Practice of Soil Science: The Soil as a Natural Resource” (Wiley-Blackwell Publishing), “Soils for Fine Wines” (Oxford University Press), “Understanding Vineyard Soils” (Oxford University Press), and “Healthy Soils for Healthy Vines”, co-authored with Mark Krstic (published by CSIRO Publishing and CABI). His scientific activity is centered on the soils under vineyards as well as on environmental issues, such as climate change and the sequestration of soil carbon. Professor White is the author of more than 200 publications (books and papers) with a record of more than 10.000 citations and a remarkable h-index of 52 on Google Scholar and 41 on Scopus.
Robert, first of all thanks a lot for your availability for this interview.
The first question is a classical one for the blog: how was your passion for soils born? And why vineyard soils?
I was stimulated to follow a career in soil science by a lecturer at university. For many years subsequently I worked in broad-acre agriculture in various parts of the world, even after I returned to Australia in 1992. However, on a soil science field trip to the Great Western vineyard in Victoria I was struck by the fact that the vineyard manager paid no attention to below ground in the vineyard – it was all about the canopy and vine physiology. So I realized that there was a big opportunity for an input of soil’s knowledge into viticulture, especially in Australia, where the above ground focus was driven by people like Richard Smart, John Gladstones and Brian Crosier. In 1999 I decided to take study leave in Berkeley California, where a good friend of mine, Professor Gary Sposito, had offered me an office and financial support. I went there to ‘tool up’ on vineyards and gather material for my first book on soils and viticulture – Soils for Fine Wines, published in 2003. The Californians were extremely helpful.
Before that, together with one of my research assistants we started soil water measurements in several vineyards on the Mornington Peninsula, and so the story of my involvement with vineyards blossomed from there.
You have written many things on terroir concept and use (and above all its misuse).
What is terroir for you?
I have no particular perception of terroir. Many definitions of terroir have been given and I accept that wine terroir is a multifaceted concept embodying three broad categories of factors: natural factors that are associated with the environment (sometimes called “endowments”); human factors – involving the use of techniques in the vineyard and winery that are specific to an individual region (sometimes referred to as “technologies”), and historical factors – reflecting widespread public knowledge of the wine coming from a region and recognition that this has been a long tradition. In my work I have focused on the soil component of the environment.
In all the scientific debate about how one, or a combination of factors determines a site’s terroir, one point should always be borne in mind: that is, the distinctive character of a wine that is an expression of a site’s terroir is ultimately determined by its sensory properties (taste, mouth feel, aroma and so on) and this depends on the consumer. Vignerons and wine writers will try to influence the reception of a wine by consumers, often with flamboyant descriptions of the wine’s individual character and appeal, but it is up to the consumer to judge a wine and hence the appreciation of a wine’s terroir can be very variable.
How important is terroir for wine quality?
Terroir and wine quality are not necessarily related. Terroir reflects a sense of place and tradition, as I alluded to in my previous answer.
Quality refers to how well a wine is made and depends on the quality of the fruit used, the skill of the winemaker in converting that fruit to wine, and attention to detail in the cellar. Again, the assessment of quality will depend on the consumer, although in this case the consumer ought to be an experienced wine buff. One might expect that a wine of poor quality would not reflect the terroir of the site from which it came.
In what way are Australian soils different from other soils worldwide?
Viticulture for wine grapes is carried out mainly in southern Australia, ranging from regions with a Mediterranean-type climate in southwest Western Australia, through to southeast South Australia, to Victoria and southern New South Wales up to the Hunter Valley, and finally down to Tasmania.
As one can imagine, vineyards covering such a wide (but not necessarily contiguous) area encompass a great variety of soils. Consequently, one can find soils similar to most of these Australian soils elsewhere in the world. However, there is one soil type (at the higher classification levels) that is very common in southern Australia and not so common elsewhere in the world, and that is the ‘duplex’ soil.
This generic name derives from the soil profile, which is typically one of texture-contrast, e.g. a sandy loam A horizon with a sharp boundary over a clay loam-clay B horizon.
These soils pose particular management problems because, depending on their genesis, they can have acidic or sodic subsoils, both of which conditions can inhibit root development. In the better winter-rainfall areas in the coastal belt, these soils can periodically be waterlogged at the top of the B horizon. However, Australian vignerons have generally learnt to overcome the challenges of these soils, in the main by trying to improve soil structure through the use of cover crops, mulches and composts.
Do you think that these differences give special imprinting to Australian wine quality as compared, e.g., to French and Italian wines?
As I said in answer to an earlier question, wine quality is determined by the quality of the fruit used, the skill of the winemaker and attention to detail in the cellar. This applies to any wine be it Australian, French or Italian. However, the terroir of a site can confer differences among wines and, since terroirs can be very site-specific, one might expect some Australian wines to be distinctive. Although this would not apply to wines made from fruit sourced from several regions (e.g. Penfolds Grange), such wines can still be of high quality. Wine styles, which largely reflect winemaking methods, can also be different from region to region within a country and between countries.
You have written a very interesting book: “Healthy Soils for Healthy Vines: Soil Management for Productive Vineyards”. Can you explain to our readers what is meant for soil health?
Soil health is now a widely used term that is broadly synonymous with soil quality, which in the agricultural literature connoted a soil’s ‘fitness for purpose’.
However, soil health has now largely replaced soil quality as a descriptor, primarily because it more directly implies the biological condition of a soil. Increasing emphasis has been placed on a soil’s biological condition in recent years. This is partly because this aspect has been underplayed relative to soil physical and chemical conditions in the past, and partly because we are learning much more about the structure and function of the soil microbiome. Throughout agriculture, including viticulture, a practical outcome of this change in emphasis is the uptake of ‘regenerative agriculture’ and organic and biodynamic farming.
We discussed the topic of the microbiome with Professor Massimo Labra who illustrated its characteristics and introduced us to the topic HERE.
Why soil health is related to healthy vines?
The vine is a perennial and vineyards are expected to produce for many years. If the soil in which the vines grow does not have the correct balance of physical, chemical and biological properties, the vines’ growth will be affected and they can become unhealthy: that is, they do not produce good quality fruit.
Is soil health related also to wine quality?
Yes, as I said earlier wine quality depends on the quality of the fruit from which the wine is made, and this depends on the health of the soil.
There are few scientists worldwide concentrating on vineyard soil characteristics. When I navigate the web, I find that geologists are the main scientists trying to find a correlation between wine quality and geology of the environment where the vines grow. Yet, rocks are the basis for pedogenesis, and vines grow on soils from where they take nutrients. Do you have any explanation why soil scientists seem not to be interested in vineyard soils?
I think perhaps your question refers to the number of soil scientists studying vineyard soils. One explanation may be that this reflects the importance of viticulture relative to broad-acre agriculture that produces staple foods and fibre. Wine, after all, is not a life-sustaining product. Secondly, the science of geology is older than soil science and so geologists may have had a ‘head start’ in exploring the complexities of what goes on below ground. Thirdly, there have been some influential books on wine and geology published over the years such as Pomerol’s Wine and Winelands of France. Geological Journeys (1989), Wilson’s Terroir. The Role of Geology, Climate and Culture in the Making of French Wines (1998) and most recently Maltman’s Vineyards, Rocks and Soils. The Wine Lover’s Guide to Geology (2018).
But as you say, the vine grows in soil even though this may be quite shallow, so our first port-of-call in studying vine growth and grape production should be the soil. I have tried to present that argument in my books.
I just published an article on the use of the “mineral” descriptor right here together with Dott. Bambina, an enologist, and Professor Conte.
What is your opinion about the use of the term “minerality” used in wine tasting?
Often wine writers use the term ‘minerality’ in association with adjectives such as ‘slatey’, ‘flinty’ and ‘chalky’ to imply a taste in the wine which is directly determined by the soil in which the vines are grown.
However, most soil scientists and geologists do not accept this direct relationship between soil minerals and wine taste, with the possible exception of a salty or even ‘soapy’ taste due to the mineral halite (sodium chloride) in the soil. However, research conducted on French and New Zealand Sauvignon Blanc wines suggested that experienced wine tasters could detect a mineral taste, primarily due to the absence of the floral tastes and aromas often associated with such wines. The most likely explanation for a ‘mineral’ taste is that a specific flavour compound is derived from the grapes during ripening or is synthesized in the wine during fermentation.
What about its use by the enologists who apply the term to indicate a relationship between soil and wine flavor?
Enologists are wine tasters by profession and they will describe all sorts of flavors and aromas in the wines they make and taste. Some of the terms used are very imaginative, such as James Halliday, the doyen of Australian wine writers who is an erstwhile winemaker, describing a ‘citrus-infused minerality’. Consumers may or may not be convinced, but if the imaginative descriptors entice them to try a wine, the enologist and wine writer will have achieved their objective.
What does sustainability mean for you?
Sustainability in agriculture can mean different things to different people. Individual organic farmers may argue that their system is sustainable if they practice recycling and do not bring anything in from off-farm. But in the long term, if harvested produce is leaving the farm, and there are losses from the soil, such a system will eventually ‘run down’ and therefore not be sustainable. On a larger areal scale, if materials are brought onto farms from external sources, the whole system is not sustainable because resources are being depleted from somewhere in the system. But this may take a long time to show up.
On a much larger scale again, there is the question of human civilization and the waste materials generated and largely disposed of in the environment. For how long can that be sustainable? We might also speculate that in an even longer timeframe, Earth’s volcanic activity may replenish some of the raw materials we need for our existence, and hence delay the onset of unsustainability. In other words, sustainability is meaningless unless we specify a scale of reference and a timeframe. But one thing is certain, it is very difficult to predict the future, as the onset of the current Covid-19 pandemic should teach us.
Last year a paper titled “What are the realistic expectations for making money out of carbon credits in vineyards?” appeared in the journal “Australian and New Zealand Grapegrower and Winemaker”. Can you tell our readers what are carbon credits and why they are important?
Carbon credits are important in any scheme for offsetting greenhouse gas (GHG) emissions, primarily consisting of carbon dioxide from the burning of fossil fuels. Every tonne of extra carbon that can be sequestered in soil (mainly in soil organic matter) in the long term (ideally 100 years) can be said to offset the emission of 3.67 tonnes of carbon dioxide equivalent (CO2-e). Superficially, this looks to be an attractive proposition because increasing soil organic matter is generally good for soil fertility and crop productivity. However, such an offsetting mechanism should not excuse governments, industry and individuals from taking action to reduce greenhouse gas emissions from various sources – mining, power generation, manufacturing, clearing land, transport, buildings and houses.
By going back to the question asked in the title of your article on “Australian and New Zealand Grapegrower and Winemaker”, can you briefly summarize your answer for our readers? Is it possible to make money by carbon credits applied to vineyards?
My article referred specifically to Australian vineyards and the possibility of earning carbon credits under the Australian government’ s Emission Reduction Fund (ERF). These credits are called Australian Carbon Credit Units (ACCUs) and are supposed to be equivalent to Kyoto units. To earn these credits a vigneron must implement a vineyard management practice that has not been in place for the previous 10 years and commit to maintaining this for a minimum of 25 years. There are significant costs associated with compliance in the first three years in taking soil samples according to an approved protocol and having these samples analysed and the results audited. Because there is uncertainty as to whether vineyards are eligible under the scheme, no vineyard has been registered under the ERF. Carbon credits are awarded per tonne of CO2-e sequestered per hectare. In vineyards that are cultivated under-vine, the area in each ha that can accumulate soil carbon is reduced. Given that the value of an ACCU has averaged only AUD12 per tonne of CO2-e over the past 6 years, the cost of participation is likely to exceed the benefit to be gained from sequestering soil carbon.
I have seen that you have commented on the 4p1000 initiative discussion. What does the acronym stand for? And why is it important?
The 4p1000 proposal advocates an annual increase of 0.4 percent in soil carbon in soils globally. This is deemed to be important because this rate of increase has been estimated to offset the annual addition of CO2 to the atmosphere due to human activities.
Why do you think that the 4p1000 initiative should have another name?
Phillippe Baveye and I argued in an article in Ambio (2019) that the launch of this initiative at the Paris Climate Conference in 2015, and its subsequent promotion, might persuade policy makers that the world’s GHG emission problems could largely be solved by soil carbon offsets. We argued that this was unrealistic in the timeframe in which effective action to reduce emissions needs to be taken. Moreover, it could give governments a ‘fig leaf’ behind which they could hide and not take the tough decisions necessary to reduce emissions in other ways. Hence, we said it should be called an ‘aspiration’ rather than an initiative.
I understand from your paper in “Sustainability” that in Australia you have the same problems as we have in Italy concerning the contrast between science and pseudoscience. This is based on the general distrust in science and scientific activity. Which is, according to your opinion, the reason for this general distrust?
Well, I would not say there was a general distrust of science here, but since the development of the internet and social media, many unorthodox ideas and opinions have been circulated that are contrary to scientific knowledge. Since the general level of science literacy in the community is not high, these unorthodox opinions have gained some traction. However, what we were referring to as ‘alternative philosophies’ were land management practices that were not validated by rigorous science, which were in some cases based on ‘belief systems’.
What are, in your opinion, the possible solutions to overcome this distrust?
Science needs more champions, that is, reputable scientists who can engage effectively with the general public. An effective ‘engager’ is one who is not a narrow specialist and who can communicate his or her enthusiasm for science in a non-condescending way. The person also needs to have good rapport with the media – journalists and media program presenters. Not many can do this. We have a excellent communicator in Australia called Dr Karl Kruszelnicki (find him on Google).
Let me ask you a provocative question: what do you think about biodynamic viticulture based on Steiner’s suggestions?
Rudolph Steiner was a polymath who in the penultimate year of his life gave a series of lectures on agriculture and the cosmos. From those six lectures the farming practice now called biodynamics has evolved. The choice of this name was remarkably good marketing because it has a touch of mystery and connotes a vigorous life force.
Depending on the soil and its organic inputs, biodynamic vineyards may suffer nutrient deficiencies over time and pest/disease control may be a problem. It is also labour-intensive, so difficult to implement on a large scale, but this can be an advantage in small vineyards because it means the vigneron is frequently in the vineyard observing the vines. Biodynamic viticulture depends heavily on the special preparations that are applied to soil and vine. However, as yet there is no conclusive evidence that these preparations change the composition and function of the soil microbiome in a way that improves vine performance relative to that in healthy ‘non-biodynamic’ soil. Nor in wine tasting have biodynamic wines been judged to be consistently better than wines from the same site produced organically or conventionally. In the end, biodynamics is a ‘belief system’ of a vigneron’s choice.
Another provocative question: assume that you get an unlimited amount of money from any supranational public authority. You can manage this money for viticulture, without even territorial limits, any control, constraints, and no reporting obligations. How would you use it?
Given the present state of the global economy and the wine industry in particular, I would buy a prestigious winery and keep on making wine until I had used up all the money.
Last: which is your favorite wine?
I have enjoyed many well-made and some distinctive wines from many countries. It is hard to pick a favorite…
The latest (really!): Australian, French, American or Italian wines?
Of Australian wines, the one I consider to be consistently the best is Henschke’s Hill of Grace shiraz from South Australia. Another excellent wine is the top-level Pinot Noir produced by Bass Phillip in Victoria. In Europe, a late-harvest Chateau d’Yquem stands out in my memory. With my wife, I very much enjoyed a Pinot Grigio from the Friuli region of Italy at dinner in Cormons some years ago.
Thank you Robert, it has been an honor to host you here.