Improved Methodologies for the Inoculation of Prairie Legumes in Roadside/Revegetation Settings
Peter H Graham, Elena Beyhaut, Becki Tlusty
Report no. MnDOT 2008-48
Response to five different inoculation treatments has been determined in a three-year-old prairie area established at the Becker Sandplain Experiment Station in Fall 2004. Seed inoculation was generally ineffective, but overall legume numbers and biomass in the prairie restorations were enhanced by both soil-applied granular and cover-crop applied inoculants, with soils collected from the prairie areas in 2007 also showing marked improvement in the soil quality traits Microbial biomass C and N as a result of inoculation. When Dalea rhizobia were recovered from soil in the different prairie plots, and identified using BOXA1R-PCR, only 2% of the strains from the seed inoculation treatment identified with the inoculant strains, whereas 53% -100% of the rhizobia from soil in the other treatments identified with these strains. Dalea plants inoculated with rhizobia recovered from soil and identifying with the inoculant strains outyielded those inoculated with non-inoculant strains by more than 100%. In contrast, when slow-growing rhizobia from Desmodium canadense were recovered from soil and characterized, only 13.7% of the strains identified with the inoculant strains used. Most were not intended for Desmodium per se but identified with the inoculant strains intended for Chamaecrista fasciculata, the legume species most evident in the first season after planting. Inoculation with high potency granular soil-applied inoculants improves both the nodulation and establishment of prairie legumes, and the quality of the prairie, but species differences in response to inoculation require further study, particularly relative to host establishment pattern, host/strain compatibility, spatial variability in soil and environmental influences.