Practicing spontaneous or sown inter-row grassing in vineyards
From Triple Performance
Spontaneous or sown inter-row grassing in vineyards consists of maintaining or sowing a permanent or temporary vegetative cover between the rows of vineyards not for harvest but to provide ecosystem services.
Benefits
- This technique primarily allows to improve the physical fertility and biological fertility of the soil through mechanical action by limiting water and wind erosion, runoff and transfer of chemical elements to groundwater.
- It also plays an important role in maintaining soil fauna, promoting beneficial organisms, reducing pest populations and disease risks.
- Sown grassing helps to reduce the abundance of harmful weed flora or to modify the communities present in the plot. This technique thus helps to limit the use of herbicides.
- Temporary grassing is most often referred to as "green manure" and helps fertilize the vineyard.
Success conditions
Ideally for winegrowers is to allow the spontaneous flora to develop, rich in diversity, adapted to the terroir and which does not require sowing. A soil cover of 50% is considered effective to improve water infiltration and reduce runoff (Andrieux, 2015). However, too much biomass can increase the risk of frost.
Sowing is recommended when natural grassing does not meet the producer's objectives such as controlling undesirable species or increasing the organic matter content.
Technique details
Species selection
- In the case of sown grassing, species choice should be based on the pedoclimatic situation and the expected behavior of the cover (competition, longevity, drought resistance). Mixtures are more interesting than single-species sowings because they increase the probability of establishing at least some of the sown plants and allow the cover to accumulate services.
- For permanent sown grassing, perennial species ideally lasting 3-4 years should be planted to ensure cover maintenance over several years.
Grassing can therefore be spontaneous or sown with annual or perennial species depending on the objectives (Table 1). Types of grassing can be alternated.
| Examples of species that can be planted in permanent sown grassing | Examples of species that can be planted in temporary sown grassing | Services provided by plant families | |
|---|---|---|---|
| Grasses | Red fescue (Festuca rubra) semi-spreading, English ryegrass, sheep fescue, meadow fescue, Italian ryegrass, meadow grass | Barley, oat, rye, triticale, ... | Improve soil surface structure thanks to their dense and powerful fibrous root systems.
Limit leaching of fertilizing elements. Control weed flora with species having strong ground cover ability. |
| Legumes | Purple clover, sainfoin, Alexandrian clover, Persian clover, subterranean clover, dwarf white clover type huia, minette, bird's-foot trefoil | Faba bean, common vetch, fenugreek | Improve soil structure at depth with species having taproot systems.
Root exudates play an important role in plant-microorganism interactions that promote soil biological activity. Capture atmospheric nitrogen → enrich the soil in nitrogen. |
| Crucifers | Forage turnip, white mustard, forage rapeseed, ... | Improve soil structure at depth thanks to taproot systems.
Root exudates play an important role in plant-microorganism interactions that promote soil biological activity. Mobilize sulfur and potash and make them available at the surface, improve nutrient assimilation, good nitrate traps. |
Examples of species and sowing rates for permanent and temporary grassing adapted to soil type and climate are available page 38 of the Agrobioperigord dossier.
Establishment
- Grassing is established on planted or newly planted vineyards. Anticipating the presence of grassing at vineyard establishment by choosing vigorous plant material allows more flexibility later but remains a risk due to the water constraint the cover may cause while the vine root system is not yet established.
- Seedbed preparation is done with a tooth harrow to loosen the top centimeters of soil, combined with a rotary tool to break clods and level the soil surface.
- Sowing is generally done in autumn, after the harvest, at a depth of 1-2 cm for permanent grassing and 2-4 cm for temporary grassing mixtures. Spring sowing is also possible but establishment will be more difficult.
- It is possible to use a direct seeding tool or a drill combined with a cultipacker.
- Prefer broadcast sowing over row sowing.
- Rolling after sowing ensures good seed-to-soil contact and thus increases germination chances. Increasing seeding rates is advised if rolling is not possible.
Fertilization/irrigation
- Generally, no fertilizer input is required. However, organic amendment can be considered before grassing establishment on "poor" plots.
- Nitrogen input can be applied localized under the vine row or foliar between flowering and cluster closure stages in case of excessive nitrogen competition, to avoid additional vigor of the cover.
- Legumes in temporary covers do not compete for nitrogen with the vine.
- Irrigation of the vegetative cover can be considered at sowing.
Management/destruction
- Permanent grassing is managed about twice a year by mowing. Contrary to common belief, it is necessary to let the cover plants flower at least once during the season to complete their cycle (annual plants) and become less competitive with the vine.
- Frequent mowing in the first years ensures good soil cover.
- Recommended renewal of the turf is every 5 years but can be extended to 8-10 years depending on its cleanliness.
- Temporary grassing is destroyed in spring. The destruction method depends on the final service sought. To:
- Fight erosion, leave a surface mulch preferably by mulching or mowing. Rolling is also possible. Mowing also provides fresh organic matter to the soil which will be decomposed by soil biological activity and fauna.
- Control weeds, mulch the cover with displacement under the row.
- Grassing can be temporarily destroyed in case of severe drought. Mechanical weeding or thermal weeding can be performed on the row. The latter is possible in regions not at risk for fires.
- Testimonials from winegrowers exist on the establishment of permanent and temporary grassing.
Points of caution
- Grassing can be detrimental and cause competition for water and nitrogen resources with the vine in certain production contexts and pedoclimatic conditions. It is therefore advised to reduce the grassed area, i.e., the number of inter-rows (1/2 or 1/3) and the width of the strip. Temporary and permanent covers can be alternated on the plot.
- Cover competition can lead to reduced vine vigor and yield. Thus, the establishment strategy and grassing should be adapted according to these parameters.
- Grassing increases the risk of spring frosts in low vine training systems by creating a humid microclimate near the buds. The cover must be kept short during the risk period. This effect is negligible when buds are more than 30 cm from the vegetative cover[1]. The risk is also observed at the bottom of slopes.
- It is not recommended to grass young vines less than 4 years old due to excessive water and nitrogen competition[2].
Some actions, projects, programs
The GIEE "Les enherbeurs", "Les couvreurs de vigne" and "Vignes en association" in Occitanie work on these methods of cover crops establishment in vineyard inter-rows.
Decision support tools
A GARANCE guide (Guide for Weed Recognition Assistance in Nouvelle-Aquitaine and Advice for Grassing Management) exists to distinguish invasive weeds in vineyard plots from those to protect.
Sources
- Inter-row grassing in vineyards - Chantelot E. - ITAB, Technical brochure, 2003 - http://itab.asso.fr/downloads/Fiches-techniques_viti/viti%20enherbement.pdf
- Criteria for successful grassing - Réussir, Press article, 2015 - https://www.reussir.fr/vigne/les-criteres-de-choix-pour-reussir-lenherbement
- Cover crops and green manures in organic viticulture - Maille E. - Agrobio Périgord, Technical brochure, 2017 - http://www.agrobioperigord.fr/upload/article-couvert-&-engrais-verts-en-viticulture-bio-auxilliaire-bio-frab-mai-2017.pdf
- Permanent grassing in Jura - Bourdenet M., Delorme G. - Chamber of Agriculture Jura, Technical brochure - https://www.sv-jura.com/medias/technique-viti-vinicole/infos-pratiques/gestion-sols/Guide_technique_VF_MH.pdf
- Sown inter-row grassing - EcophytoPIC, Technical brochure, 2013 - https://ecophytopic.fr/sites/default/files/actualites_doc/viti_enherbement%20sem%C3%A9%20inter-rang.pdf
- Temporary grassing in viticulture - Forget C., Feraud O., Lion J., Jeoffre A., Bennamane S., Vergé J.L. - Chamber of Agriculture Aude, Technical brochure, 2019 - https://aude.chambre-agriculture.fr/fileadmin/user_upload/Occitanie/064_Inst-Aude/documents_aude/Viticulture/enherbement_temporaire.pdf
- Grapevine quality: A multiple choice issue - Poni S., Gatti M., Palliotti A., Dai Z., Duchêne E., Truong T.T., Ferrara G., Matarrese A.M.S., Gallotta A., Bellincontro A., Mencarelli F., Tombesia S. - Elsevier, Peer-reviewed journal article, 2018 - https://www.sciencedirect.com/science/article/abs/pii/S0304423817307586
- A meta-analysis of the ecotoxicological impact of viticultural practices on soil biodiversity - Karimi B., Cahurel J.Y., Gontier L., Charlier L., Chovelon M., Mahé H., Ranjard L. - Springer Link, Peer-reviewed journal article, 2020 - https://link.springer.com/article/10.1007/s10311-020-01050-5
