Cultivation of native plants for seed and biomass yield

Establishing native perennial plants on the agricultural landscape can improve ecosystem services and provide marketable products, such as seed for restoration plantings and biomass for renewable energy. Native perennials of economic and ecological interest should be examined in different planting configurations over time to determine their suitability for sustained production. Canada milk vetch (Astragalus canadensis L.), purple coneflower (Echinacea purpurea L.), and showy tick trefoil (Desmodium canadense L.) were established at two locations in Minnesota to evaluate seed and vegetative biomass yields. These forbs were established in six different agronomic designs: three strip designs (one-row, three-rows, and six-rows) and three community designs (monoculture, low-richness polyculture, and high-richness polyculture). Seed yield averaged 2995, 950, and 1157 kg ha⁻¹ for Canada milk vetch, purple coneflower, and showy tick trefoil in the first year and declined for all species over time. Biomass yields averaged 6743, 2725, and 2869 kg ha⁻¹ in the first year for Canada milk vetch, purple coneflower, and showy tick trefoil, respectively. Canada milk vetch biomass yields declined by 98% over time, and showy tick trefoil biomass yields increased by 40%. Seed and biomass yields were the lowest in one-row strip design and greatest in the community designs, with little difference between monocultures and polycultures. Results suggest that production is maximized in community designs and that purple coneflower and showy tick trefoil have the potential for multiyear yields.