Nitrogen Cycling in Switchgrass Varieties

The Science

Determine differences in nitrogen (N) acquisition and conservation between switchgrass varieties to optimize growth with the least amount of fertilizer usage.

The Impact

  • N fixation was highly variable among switchgrass varieties, but in general lowland ecotypes had significantly higher yields, N translocation, and root N fixation, with lower soil N fixation than upland ecotypes.
  • N cycling differences might be due to root and soil microbiome differences in switchgrass varieties.
  • Many switchgrass varieties can achieve high yield without N additions, decreasing the economic and environmental cost of growing this bioenergy crop.


Measure N fixation, N mineralization, and N translocation along with soil moisture and N content in switchgrass varieties from upland and lowland ecotypes.

Principal Investigator(s)

G. Philip Robertson
Michigan State University


Roley, S.S., Ulbrich, T.C., Robertson, G.P. “Nitrogen fixation and resorption efficiency differences among twelve upland and lowland switchgrass cultivars.” Phytobiomes 116, 071802 (2020). [DOI:10.1094/PBIOMES-11-19-0064-FI]