Forage mixtures adapted to drought in mountain areas

The frequency and intensity of summer droughts are increasing as a result of climate change. In mountainous areas, where the growing season is already short, the yield and quality of grassland forage are increasingly diminishing during dry years. The #DryMountProject (2023-2027) aims to test new forage mixtures that are better adapted to drought. It is being conducted in the five partner cantons of the experimental station for Alpine and Mountain Farming.

Mixture composition

The DryMount project aims to create drought-resistant mixtures that produce good yields of high-quality forage when rainfall conditions are optimal for grass growth.

Nine new mixtures were created for the trial in order to determine the best compromise between productivity and drought resistance. Each mixture contains one dominant main species which is productive and others (0, 15 or 30%) considered to be drought-resistant. The dominant species are either cocksfoot grass or meadow foxtail, or a combination of the two, supplemented by other species commonly found in standard mixtures (e.g. Kentucky bluegrass, timothy, red clover). Other more drought-resistant species (red fescue, ribwort plantain, common bent and bird’s-foot trefoil) are then added to these basic mixtures. Two mixtures commonly sown in mountainous areas were used as controls. A total of eleven mixtures were sown on the five sites in May-June 2023, along a rainfall gradient (850 to 1600 mm).

Location of the five DryMount study sites in the cantons of Bern, Valais, Grisons, Uri and Ticino with altitude shown in black and annual precipitation in blue.

Responses of mixtures to drought

In order to gain a better understanding of the resistance of these mixtures to water scarcity, a drought simulation is being set up at the experimental site in the canton of Berne during the summers of 2024 and 2025. The mixtures will be sown twice, with one half being exposed to ambient rainfall at the site, and the other half receiving only 70% of local rainfall during the summer months (June, July, August), according to climate forecasts for 2060.

The yield, botanical composition and forage quality of the mixtures, as well as the functional traits of the leaves and roots of the different species, will be evaluated over a four-year period (doctoral thesis of Emilie Roinel, 2023-2027).

Preliminary results (2023)

A first cut of forage was harvested at four of the five sites between August and September. In a year marked by droughts and intense summer heat waves, the results of these first harvests indicate that forage yields are higher in mixtures containing 15 and 30% of drought-resistant species, with up to 25% and 44% more forage respectively compared to mixtures without drought-resistant species. These initial findings are encouraging, given that they were obtained in the first year after sowing.