Can a Mixture of Perennial Grasses with Contrasting Growth Strategies Compose Productive and Stable Swards?

Abstract

Core Ideas Mixing grass forage species can increase forage yield and stability. Overyielding was more influenced by increasing leaf biomass rather than stem biomass. Dominant grasses with contrasting growth strategies can compose productive and stable pastures. Mixtures composed of species with different growth strategies (e.g., exploitative and conservative), which have different abilities for resource capture and use, are thought to improve grassland ecosystem services. However, plant species that compete better for limiting resources can become dominant. This study examined whether potential dominant perennial grasses with different growth strategies can compose productive and stable forage mixtures under low competition for resources (nutrients and light). Arrhenatherum elatius L. (exploitative), Festuca arundinacea Schreb. (conservative), and Dactylis glomerata L. (moderately exploitative) were sowed as monocultures and as a three‐species mixture. Pastures were fertilized to maintain high soil fertility levels and mowed by half when their canopies reached 20 cm in height (95% of light interception in the vegetative stage) allowing for over 2 yr of data collection. The proportion of each species in the mixture remained unaltered throughout the experimental period. Transgressive overyielding was not observed; however, the mixture presented a similar yield to the most productive monocultures (10,200 kg DM ha−1 yr−1), although D. glomerata, which presented the lowest yield in monoculture (6400 kg DM ha−1 yr−1), comprised 68.1% of post‐cutting biomass in the mixture. Arrhenatherum elatius and F. arundinacea populations presented less yield variance in monoculture, but higher yield stability was observed in the mixture. Overyielding in the three studied species was strongly affected by leaf production. Mixtures composed of perennial grasses with different growth strategies when grown in nutrient‐rich soil and under conditions of low light competition can compose productive and stable swards, while maximizing leaf production.