Brome Control and Microbial Inoculation Effects in Reclaimed Cool-Season Grasslands

Abstract

Introduction and subsequent invasion of smooth brome (Bromus inermis Leyss.) into native cool- and warm-season grassland communities has become problematic where presence of native species is important or mandated. The objectives of this study were to examine the efficacy of burning, grazing, and herbicide to reduce smooth brome production and cover while minimizing coincident detrimental effects on cool-season grasses in a reclaimed surface coal mine site. Concurrently, the project also investigated effects of microbial inoculation on respread topsoil subjected to long-term storage and associated effects on seeded cool-season grasses subjected to brome control treatments. Results indicated that grazing and burning were most effective after 2 years of treatment. Smooth brome biomass was lowest in reburned cells (mean +/- SE, 189 +/- 77 kg ha-1) followed by regrazed (294 +/- 129) compared to untreated cells (824 +/- 42) (P < 0.0001). Native grass production was highest in grazed cells (141 +/- 67 kg ha-1) followed by burning (104 +/- 41), herbicide (72 +/- 30), and untreated (30 +/- 27). Foliar cover response patterns were similar. Inoculation had little effect on microbial biomass and mycorrhizal infection. Retreated cells did show differences among months (P = 0.013) in 2000, and microbial carbon ranged from 0.07 +/- 0.01 mg/g in June to 0.12 +/- 0.01 in July and 0.12 +/- 0.01 in August, averaged across treatments. Root infection decreased as soil moisture declined. Results indicate grazing offers the greatest potential for controlling smooth brome without harming native, seeded grasses on reclaimed lands in northern mixed- prarie communities, and inoculation was unnecessary for enhancing seeded, cool-season grass growth.