PS 20-15 - CANCELLED - Can winter cover crops contribute to the sustainable intensification of dairy forage production systems in the Upper Midwest

Abstract: Overwintering cover crops can provide ground cover at a time when soils are vulnerable to erosion and nutrient losses, particularly in dairy forage production systems where fall manure applications are common. However, in the Upper Midwest, there is limited time to plant cover crops following corn harvest and there are few species that reliably overwinter. Winter cereal rye is a resilient and winter-hardy species that can be planted late in the fall, produce high amounts of biomass and high-quality spring forage, and is, thus, often planted in monoculture. On the other hand, cover crop mixtures can deliver multiple ecosystem services while providing quality forage but have been relatively understudied in the context of sustainable intensification of dairy forage systems. We present initial findings from an ongoing study that seeks to quantify the benefits and tradeoffs associated with cover crop species composition, i.e., cover crop monocultures versus various mixtures containing winter cereal rye, winter triticale, hairy vetch, and winter camelina, on spring forage production, forage quality, soil nutrient uptake, and pollinator diversity and abundance. Data from year one of the study indicates that forage production (dry matter) was not statistically different between winter cereal rye (3524 kg ha^-1), winter triticale (3642 kg ha^-1), binary mixtures of each of these species with hairy vetch (3271 and 3014 kg ha^-1, respectively), or three-way mixtures with the addition of winter camelina (2878 and 2764 kg ha^-1, respectively). However, pollinator abundance was greatest in mixtures containing winter camelina, which flowers in early spring. Results from soil nutrient uptake and forage quality analyses will provide additional ecosystem services metrics to further evaluate potential synergies and tradeoffs with the inclusion of diverse winter cover crop mixtures and their contributions to the environmental and economic sustainability of dairy forage systems of the Upper Midwest.