10 facts you should know about cover crops in vineyards
What is a cover crop? What are its advantages? its drawbacks? Which cover species should be chosen? What factors should be taken into account for its management?…
Cover crops are a complex subject that raises many questions, so much so that it is sometimes difficult to find one’s way around.
Here are 10 facts you need to know about cover crops in vineyards :
1. Cover crops are plants that cover the soil between and under taller crops
Cover crops can be found between and under the rows of at the foot of a vertical crop (vineyards, orchards..). They can be natural or sown, temporary or permanent, planted in all rows or not. They represent an alternative to chemical weeding and tillage.
This technique is not new, as the Romans were already using it 2000 years ago.
Indeed, until the 1930s, this method of maintaining vineyard soils was considered a good viticultural practice, with positive effects on soil.
Later, the development of mineral fertilizers, mechanization, and an increased awareness of the nutrient and water competition between “grass” and vines led to extensive weeding in vineyards. Since the 1970s, chemical weed control has been adopted by the vast majority of vineyards in France.
2. Cover crops occupy 52% of the surface area of French vineyards
In 2016, in France, cover crops occupied 52% of total vineyard surface area. Their presence varied according to the viticultural area, from 24% in Burgundy to 99% in Dordogne. On the other hand this practice is hardly present in Mediterranean vineyards. This is because mediterranean winegrowers fear an excessive competition between cover crops and grapevines, generating water stress.
3. Cover crops favor life in the soil
Cover crops are an important source of organic matter that encourages life in the soil. They create biotopes favoring the formation of humus and the development of microbial ecosystems.
4. Cover crops protect the soil from erosion and limit pesticides transfer into soil and water
Cover crops prevents soil erosion by acting as a protective layer. The roots of the herbaceous plants hold soil particles in place, thus preventing erosion by water and wind. Surface vegetation creates a physical barrier that reduces the direct impact of raindrops, thereby decreasing the risk of soil loss. As a result, cover crops keep vineyard soils healthy, preserving their fertility and ability to support growth. Additionally, they act as a natural barrier against the pesticides transfer into soil. Vegetation captures some of the pesticides that could otherwise be washed away by precipitation or irrigation, thus limiting their impact on groundwater and watercourses. By promoting microbial biodiversity in the soil, herbaceous plants also contribute to the natural decomposition of pesticide residues.
5. Cover crops create competition
Cover crops create competition for water and nutrients between the plant cover and the vine. This competition is strongly influenced by climate – in particular by sunshine and rainfall – and must be controlled and adapted to the desired objectives. If it is too strong, the vine will become water stressed and will not absorb the appropriate amount of nitrogen.
The competition caused by cover crops occurs during the vegetative season of grapevine and during berry ripening. Thus, it begins at bud break and becomes more pronounced at flowering. During the vegetative rest period (autumn and winter), there is no competition between cover crops and grapevine.
If competition is too important, it can result in grapevine stress. Therefore, to control competition, it is possible to adjust the width of the grass cover or to irrigate. Be careful, however: to be effective, these measures must be taken at the right time.
6. Cover crops are not recommended for young vines
Because of water and nutrient competition, the French Institute of Vine and Wine (IFV) advises against growing cover crops in young vineyards that are less than 3 years old. Plants are not sufficiently developed to draw water and nutrients from the soil deep layers.
With the exception of particularly vigorous plots, cover crops should not be considered before the 4th or 5th year. However, grass strips can be planted around the plot to limit erosion.
7. Cover crops help to control vine vigor
Cover crop can be used to limit problems related to excessive plant vigour. Water and nutrient competition results in a reduction in vine vigour and yields. By controlling cover crops, winegrowers can control this balance, to improve the quality of their wines.
8. Cover crops can improve wine quality
Cover crops can play a beneficial role in improving the quality of grape musts by influencing both vine vigor and soil microbial life.
Competition between the vegetation cover and the vine can lead to a reduction in vigor, resulting in grape musts that are less acidic and have a higher alcohol potential. For red grapes, this potential improvement in quality also translates into an increase in phenolic compound concentration.
Moreover, scientific research has established links between soil microbial activity and fermentation processes, resulting in variations in the taste, aroma, and chemical composition of the wines produced. Thus, by promoting soil microbiota, cover crops could also positively influence wine quality.
9. The effect of cover crops depends on the species composing them
Different types of cover crops will have very different effect on vines. For this reason, the choice of cover crop species must be accurate : winegrowers must take into account the wine production objectives, soil structure, vigor, berry quality, etc. The most important factor for defining the species to be planted is the desired or acceptable competition level in a given plot or vineyard. The other elements then help to refine the choice of species.
The species that are the least competitive for grapevines are legumes and grasses. Their cycle ends in May, so they disappear during the summer season, which avoids any competition for water during the hottest periods.
Finally, the possibility of a natural, spontaneous grass cover should not be neglected. This is often the simplest (and least expensive) option. The species naturally growing in the plots are already adapted to their climate and soil structure. Moreover, they are easier to destroy a strip of planted grass, which is a significant advantage in managing competition.
10. Cover crops can be managed using digital tools
Some winegrowers give up on the benefits of cover crops to avoid water competition, even though a controlled competition could be sustainable for grapevines.Indeed , cover crops can be now managed based on precise information concerning the water status of plots.
In order to facilitate the water and nitrogen management of crops, ITK has developed a smart digital solution: Vintel. The Decision Support System (DSS) Vintel® helps to manage irrigation and nitrogen fertilization in real time according to vine water and nitrogen needs. This solution provides winegrowers with precise knowledge of the water and nitrogen status of the plots, for a better management of the vineyard
In addition, for regions where irrigation is possible, Vintel provides irrigation recommendations adapted to each plot and target wine profile, based on agro-environmental and artificial intelligence models. This allows yield optimization and managing berry quality, plot selection, water management, etc.
In short, with Vintel, you have a real-time view of the water and nitrogen status of your vines. Want to know more? Contact-us !
