Biomass Production of Monocultures and Mixtures of Cup Plant and Native Grasses on Prime and Marginal Cropland

Abstract

To date, most candidate systems for producing herbaceous cellulosic biomass have been composed of monocultures of perennial or annual grasses. Ecosystem goods and services provided from these biomass feedstock production systems could be increased dramatically with mixing of one or more forb species that would increase biodiversity and provide habitat for pollinators. Cup plant ( Silphium perfoliatum L . ) is featured with many desirable characteristics, such as high biomass potential, adaptation to marginal soils, and attractiveness to pollinators, desirable in a dicot species to grow in mixtures with perennial warm-season grasses. The objective of this study was to compare cup plant, switchgrass ( Panicum virgatum L.), and prairie cordgrass ( Spartina pectinata Link) monocultures to their mixtures for biomass production on prime and poorly drained marginal crop land for two years in both South Dakota and Wisconsin. In Wisconsin, monocultures of prairie cordgrass and cup plant and their mixture produced more biomass (8.1 Mg·ha -1 ) than the switchgrass monoculture and switchgrass/cup plant mixture (5.3 Mg·ha -1 ) on both prime and marginal land. While in South Dakota, drought and meristem destruction by the cup plant moth ( Eucosma giganteana Riley) caused large reductions in biomass production (1.7 Mg·ha -1 ) in both years, with the switchgrass/cup plant mixture on marginal land having the highest yield (2.1 Mg·ha -1 ). Our study showed binary mixtures of cup plant and native warm-season grasses have great potential for increasing biodiversity and other ecosystem goods and services, relative to monocultures, for sustainable biomass feedstock production on poorly drained marginal land in the northcentral USA.