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Title: Switchgrass cultivars alter microbial contribution to deep soil C

Author
item Roosendaal, Damaris
item Stewart, Catherine
item DENEF, KAROLIEN - Colorado State University
item Follett, Ronald - Ron
item Pruessner, Elizabeth
item Varvel, Gary
item Saathoff, Aaron
item Palmer, Nathan - Nate
item Sarath, Gautam
item Jin, Virginia
item Schmer, Marty
item SOUNDARARAJAN, NADHAVAN - University Of Nebraska

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2014
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Switchgrass (Panicum virgatum L.) is a perennial, cellulosic biofuel feedstock capable of growing under a wide variety of climatic conditions on land marginally suited to cultivated crops. Due to its perennial nature and deep rooting characteristics, switchgrass contributes to soil C sequestration deep in the soil profile. However, phenotypic variability in switchgrass cultivars can impact belowground plant allocation and could influence the soil microbial community. We quantified microbial contributions to SOM to a depth of 150 cm using a pulse-chase 13C labeling experiment of two 3-yr old switchgrass cultivars, Kanlow and Summer. We measured total and relative abundance and 13C signatures of phospholipid fatty acids (PLFA).The lowland variety, Kanlow, had greater total PLFAs compared to Summer, an upland, mesic variety. Community structure was dominated by actinomycetes and gram + bacteria and varied with depth. Forty eight hours after labeling, 13C signal was detected in fungi and AMF to a depth of 90 cm. Plant-derived switchgrass C was quickly transferred to microbial biomass deep into the soil and was correlated with belowground plant biomass. Belowground C transfers are essential to accurately determining cultivar-specific effects in C cycling. Will be presented at the Front Range Isotope Days, CSU Fort Collins, CO August 15, 2013.