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ARS Home » Plains Area » Mandan, North Dakota » Northern Great Plains Research Laboratory » Research » Publications at this Location » Publication #378584

Research Project: Sustainable Agricultural Systems for the Northern Great Plains

Location: Northern Great Plains Research Laboratory

Title: Kentucky bluegrass impacts diversity and carbon and nitrogen dynamics in a northern Great Plains rangeland

item Hendrickson, John
item Liebig, Mark
item PRINTZ, JEFFERY - Natural Resources Conservation Service (NRCS, USDA)
item Toledo, David
item Halvorson, Jonathan
item Christensen, Rachael
item Kronberg, Scott

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2021
Publication Date: 11/1/2021
Citation: Hendrickson, J.R., Liebig, M.A., Printz, J., Toledo, D.N., Halvorson, J.J., Christensen, R., Kronberg, S.L. 2021. Kentucky bluegrass impacts diversity and carbon and nitrogen dynamics in a northern Great Plains rangeland. Rangeland Ecology and Management. 79:36-42.

Interpretive Summary: Kentucky bluegrass has rapidly increased on rangelands in the northern Great Plains over the last 30 years reducing ecosystem services. A project was initiated in 2013 to determine the impact of Kentucky bluegrass invasion on species diversity and nitrogen dynamics. In 2 years of the 3-year project, species richness and diversity were reduced where Kentucky bluegrass was dominant. Higher production of Kentucky bluegrass and its lack of palatability after early spring resulted in Kentucky bluegrass plots having more nitrogen compared to the controls. These results are useful to ranchers and grassland managers in making management decisions to control Kentucky bluegrass. Results suggest that fire or targeted grazing should be used to control Kentucky bluegrass by reducing biomass and giving native grasses a competitive advantage.

Technical Abstract: Kentucky bluegrass (Poa pratensis L.) has rapidly increased on rangelands in the northern Great Plains over the last 30 years. There are relatively few side by side comparison on how Kentucky bluegrass invasion has affected plant diversity and nitrogen dynamics. We annually located four plots (4.9 m x 4.9 m) between 2013-2015 on a long-term (1916-2016) moderated stocked pasture at the Northern Great Plains Research Laboratory (USDA-ARS) near Mandan, ND, USA. Each site had equal parts that were either dominated by Kentucky bluegrass (KBG) or dominated by other species (CONT). Four 1/8 m2 quadrats were clipped by species, including detached plant material (litter) within in plot in mid to late July, 2013, 2014 and 2015. In 2013, soil samples were taken at depths of 0-5, 5-10 and 10-15 cm within each plot and thatch samples were hand excavated after clipping. Carbon (C ) and nitrogen (N) were determined on the aboveground biomass, litter, thatch and soil samples. KBG plots produced 28% more biomass annually than did the CONT plots. In 2014 and 2015, species richness was 0.7 to 2.1 times greater for the CONT plots than the KBG plots. Although N and C concentrations were similar between treatments for aboveground biomass, litter and thatch, when expressed on a g m-2 basis, N was 34% greater for aboveground biomass and 600% greater for litter in KBG plots than the CONT plots. Soil organic C and total soil N at 0-5 cm were 26 and 22% greater in KBG plots compared to CONT plots, respectively. Increased productivity and lack of palatability of Kentucky bluegrass may increase N in the system giving a competitive advantage to Kentucky bluegrass. Management interventions, including carefully prescribed fire and targeted grazing should focus on biomass reduction to reduce N and shift towards a more native dominated system.