Switchgrass (Panicum virgatum L.) is a native perennial grass identified as a promising biofuel crop for production on marginal agricultural lands. As such, research into switchgrass fertility and the switchgrass rhizosphere microbiome has been ongoing in an effort to increase production sustainability. We examined the effects of cultivar and phosphorus (P) fertilization on biomass yield, P removal, and rhizosphere bacterial and fungal community structure in three switchgrass cultivars: Sunburst, Shawnee, and Liberty. The Liberty cv. is the first lowland-type bioenergy switchgrass adapted to USDA hardiness zones 4, 5, and 6. On a medium soil test P clay loam soil, biomass yield response to applied P was linear, increasing 135 kg ha −1 for every kilogram of P applied prior to establishment. Average post-frost biomass yield was 9.6 Mg ha −1 year −1 when unfertilized, and maximum biomass yield was 10.3 Mg ha −1 year −1 when fertilized at 58.6 kg ha −1 P, suggesting that P application on medium soil test P soils is beneficial for switchgrass establishment and early growth. Switchgrass cv. Shawnee was more productive than cvs. Liberty or Sunburst (11.3, 10.2, and 8.6 Mg ha −1 year −1 , respectively). Both bacterial and fungal communities were significantly shaped by cultivar. These shifts, while inconsistent between year and cultivar, may reflect a selection of the microbial community from that present in soil to maximize total nutrient uptake, regardless of additional P amendments. Phosphorus fertilization did not affect microbial community structure. Results of this study suggest that the cultivar-associated selection of particular microbial taxa may have implications for increased productivity.
Bibliographical noteFunding Information:
The authors gratefully acknowledge Matthew McNearney, Joshua Larson, and Steven Quiring for their assistance with plot establishment, maintenance, and data collection. We would also like to thank Trevor Gould for the assistance with sequence data processing. Sequence data were processed and analyzed using the resources of the Minnesota Supercomputing Institute.
Funding This research was supported by USDA NIFA-AFRI Competitive Grant No. 2011-68005-30411 and by the Hueg-Harrison Fellowship.
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
- 16S rRNA
- Community structure