Climate change is forcing intelligent irrigation in wine growing

@ Hermann Pilz

Water is essential for all life processes. There can be no life without it. Therefore, it is not surprising that water is also a crucial factor in the beverage industry and in wine production. This makes irrigation for wine growing a topic more important now than ever.

trockenschäden an weinstöcken in der südpfalz
@ Hermann Pilz

In recent times, humanity has seen dramatic changes in the global environment due to climate change. Clean water has always been highly valuable, but it is now more of a precious resource than ever. All countries are having to grapple with the questions of supply, precipitation, availability, storage opportunities, protection of natural reservoirs, quality and frugal water usage. This has direct effects for the beverage industry, meaning that sustainable water management is taking on a whole new meaning for wine growing: Intelligent irrigation is essential.

Sustainable irrigation in wine growing

In wine regions all around the world, wine growing is struggling with the consequences of climate change and the stark changes in the availability of water. Even today, you can feel the effects of water shortages in declining yields and, in many cases, rising water costs. This impacts wine growing, in particular, which takes place in arid and semi-arid desert regions due to the better phytosanitary conditions and reduced need for plant protection. This not only applies to wine regions overseas such as California, Chile, Argentina, Australia and South Africa, but also to European countries such as Spain, Italy, Portugal and France – even the dry Alpine valleys of Valais in Switzerland and the dry hills of Rheinhessen where it rarely rains.

The hot, dry summers of recent decades have also impacted German wine-growing regions. Even in a rainy country like Germany where rainfall is abundant by comparison, averaging 750 mm of precipitation per year, water during drought periods can lead to water stress in the grapes. Using this natural resource frugally is just one part of the equation. Intelligent irrigation for wine growing presents another solution.

Grapes take root deep in the earth and have survival down to a fine art: They can tap water from five, ten or even more meters down. The steady shrinkage of the water table, however, is leading to stunted growth, especially in dry locations. On many of the steep slopes in Germany today, wine growing would no longer be possible without artificial irrigation. Systems such as drip irrigation, which have long been the standard for grape cultivation overseas, are absolutely essential in Germany and many other regions.

Drip irrigation: how irrigation works in wine growing

In drip irrigation, grapes largely grown with wire frames are economically supplied with water via a drip line. Through this, water is supplied selectively and only as necessary, for example if the grapes are suffering from water stress from lack of rainfall or if they need more water during their development phase. The temperatures on steep slopes can reach more than 45 degrees Celsius on hot summer days, and the need to protect the grapes’ leaves from overheating via evaporation is equally high. Above all, grapes demand sufficient water in both growth phases: when the buds flower and for the gradual growth of the berries.

weinstock bewässerung
@ Matthias Petgen

Osmotic pressure intelligent irrigation systems that supply water when it is needed, and observing water evaporation in the leaves as parameters can help to use water efficiently and sustainably. Around the world, research is being carried out into water management systems that also take into account reservoirs, canals and water-saving planting. Each plant requires different amounts of water: While plant varieties such as the eucalyptus tree drink up large quantities of water, other plant varieties in semi-arid wine regions can be planted to provide shade and effectively reduce water usage.

Available water includes the surface water in rivers and lakes, as well as rainwater in collection tanks and existing groundwater. Germany is a country with ample water and is in the fortunate position that it only uses around 15 percent of its available water for power generation, industry and agriculture. According to publications from the German Federal Ministry for the Environment, public drinking water requires only three percent of the available water supplies. Nevertheless, in the summer of 2020, many of the roughly 6,000 water suppliers in Germany had to call for frugal water usage in a number of regions.

Contaminants in groundwater complicate water treatment

Only around a quarter of the raw water taken from the natural water cycle can be used directly as drinking water. The majority requires varying degrees of treatment. Groundwater in Germany often contains high quantities of iron and manganese. For hygiene reasons, the water used on a daily basis by wineries is already-treated drinking water.

Contaminants such as phosphates and nitrates are both found largely in wine, vegetable and fruit growing regions, as well as regions with intensive livestock farming. As of 1991, member states of the European Union have been subject to nitrate guidelines. These are in place to ensure water quality by keeping groundwater and surface water from being exposed to nitrate impurities. On the whole, the guidelines have had a positive impact over the years.

In recent years, contaminants found in the water – residue from pesticides and high nitrate values –  have been attracting more and more attention. Despite its abundant water supply, for decades Germany has had problems with fertilizer residues such as nitrates and phosphates, as well as residue from pesticides. Removing the high levels of residue results in high costs for suppliers of drinking water. This is currently around 40 cents per cubic meter of water. Using fertilizers more sparingly in wine growing is therefore just as crucial as the carefully considered usage of pesticides.

Monitoring and measurement technology, management systems for irrigation and systems to treat and save water will be indispensable in the future of wine growing. You will find information about the latest technologies, treatment plants for removing iron and manganese and ventilation and filtration at drinktec, taking place from September 12 to 16, 2022 in Munich.

Dr. Hermann Pilz

Dr. Hermann Pilz has been in charge of the trade magazine WEINWIRTSCHAFT as chief editor for over 20 years. He loves writing about many different topics of the wine and spirits industry.