Temporal dynamics of free‐living nitrogen fixation in the switchgrass rhizosphere
- Biological Sciences Division, Earth and Biological Sciences Directorate Pacific Northwest National Laboratory Richland Washington USA, Department of Plant, Soil and Microbial Sciences Michigan State University East Lansing Michigan USA
- W.K. Kellogg Biological Station Department of Integrative Biology Michigan State University Hickory Corners Michigan USA
- Department of Plant Pathology Washington State University Pullman Washington USA, Department of Crop and Soil Sciences Washington State University Pullman Washington USA
- Department of Plant, Soil and Microbial Sciences Michigan State University East Lansing Michigan USA
Abstract
Free‐living nitrogen fixation (FLNF) represents an important terrestrial N source and is gaining interest for its potential to contribute plant available N to bioenergy cropping systems. Switchgrass, a cellulosic bioenergy crop, may be particularly reliant on FLNF when grown on low N systems, like marginal lands. However, the potential contributions of FLNF to switchgrass as well as the controls on this process are not well understood. In this study, we evaluated drivers of FLNF rates and N‐fixing microbial (diazotrophic) community composition in field‐grown switchgrass systems over two growing seasons with high temporal sampling. We found that climate variables are strong drivers of FLNF rates in switchgrass systems, compared to other environmental and biological factors including soil nutrients and diazotrophic community composition. Increased soil moisture availability generally promoted FLNF rates, but extreme rainfall events were detrimental. These climate‐related responses suggest a potential for loss of FLNF‐derived N contributions under projected climate shifts. We found a significant, but weak correlation between diazotrophic community composition and FLNF rates. We also observed a significant shift in the diazotrophic community composition between 2017 and 2018 and similarly measured a significant difference in FLNF rates between growing seasons. Lastly, we found that seasonal FLNF N contributions, based on measurement with high temporal resolution, has the potential to meet up to 80% of switchgrass N demands suggesting that FLNF measurements extrapolated from fewer time points or locations may underestimate these potential N contributions.
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- SC0014108; FC02-07ER64494; SC0018409
- OSTI ID:
- 1819784
- Alternate ID(s):
- OSTI ID: 1819786
OSTI ID: 1827258
- Journal Information:
- Global Change Biology. Bioenergy, Journal Name: Global Change Biology. Bioenergy Journal Issue: 11 Vol. 13; ISSN 1757-1693
- Publisher:
- Wiley-BlackwellCopyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English