Contributed by Bruce Pearse, Viticulturist
With the 2014 vintage successfully tucked away in winery and with winemakers and viticulturists beaming red smiles from exuberant tastings, we viticulturists turn our attention to celebrating vintage with some recreation and relaxation. With vintage completed, I like nothing better than relaxing with friends and trying my skills on a few wild caught fish in the northwest of Western Australia. Exmouth is our destination this year and it is a privilege to be writing this piece while having a glass of chardonnay and avoiding what has been the wettest few days that Exmouth has received in many years…. So wet up here that we are glad that the house is up off the ground and we gathered some of Margaret River’s best to bring with us! I suspect that if the rain doesn’t stop soon we may be in a spot of bother and will need to call home for additional supplies (maybe we could call the office and chopper some wine in?).
At home in Margaret River winter has arrived. Family and friends tell me plenty of rain falling there as well. With shorter daylight hours, cold weather and rainfall the grapevines respond with late autumn colours and leaf loss. The start of the dormant period in the cycle of vine life will begin. Grapevines are very robust plants and have evolved over millions of years to survive harsh winters by losing their leaves and shutting down their metabolic processes. Dormancy is really the winter survival behavior of vines grown in temperate areas.
We generally have very wet winters in Margaret River (expect 750 – 1200mm annually) and the outcome can cause leaching of mineral wealth from the soil. This leaching or loss of soil minerals has a compounding effect not only on future profitability but also on the environment and we manage this with some very thoughtful practices. The practice of planting winter crops to take up minerals that would otherwise be lost through leaching is very important. These minerals are stored in plant tissue and are released when decomposition occurs throughout early summer. This is a natural process of the plant dying and soil microbiological activity in soils that have natural moisture holding capacity proving the natural environment for biological activity. I suspect it is a basic understanding of what most would call “organics”; I would refer to “biologic farming” or “sustainable farming”. Of course once this process is better understood, then the reduction in chemical input reduces and the system becomes sustainable and “organic”.
We recognize that half of the plant biomass provided with cover crops is root system and that this is already incorporated in the soil, this is important as we may actually achieve much better change to soil structure and mineral wealth by having deep rooting and volumous root systems. The concept is to select range of plant species that is suitable for the environment and then support healthy plant growth (the bigger the root mass the better the end result). The end outcome should be better nutrient/mineral uptake and then excellent opportunities from future biologic and organic benefits.
Another benefit of having established cover crops in the vineyard is that it allows the identification of mineral deficiency through observation. We regularly test soils for mineral availability and other indicative attributes. Not always are the results that we see in analysis similar to what we see in plant health. Every year winter is different, rainfall events vary in volume and timing, temperature can be hotter or cooler and soil temperature will change. The biologic activity in soil will be variable and the complex soil chemistry with its cation and anion exchange (effecting nutrient availability to the plant root system) will challenge us. As a result of seasonal variation, plant species will respond differently and we need to take this into consideration when we assess the needs of grapevines going forward. For this we look at plant growth and also deficiency symptoms of winter and spring pasture and vine growth and then make adjustments to the mineral requirements of the plants. We use tools such as soil and leaf analysis to help support what we observe. It probably sounds complex but is simply an extension of what would normally be expected for routine plant performance analysis. Simply, if the winter cover crop is performing well, then we could expect the summer grapevine performance to be acceptable for quality wine production!
This is a constant cycle of vine improvement, a good deal occurring naturally, even when we are on holidays. A discerning bunch of caring and passionate viticulturists rising to the challenge of making the best possible Margaret River wine from our sustainable vineyards goes well for our future drinking pleasure.
Contributed by Bruce Pearse, Viticulturist
Margaret River Discovery Tours
Sean Blocksidge is the owner operator of the Margaret River Discovery Company, an avid photographer, blogger and South West WA ambassador. In 2010 he won Western Australian Guide of the Year and his tours have been rated the #1 thing to do in Australia on the Tripadvisor website for the past two years.