Browsing by Author "Williams, David G."

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    Biomass production of herbaceous energy crops in the United States: field trial results and yield potential maps from the multiyear regional feedstock partnership
    Lee, Do Kyoung; Aberle, Ezra; Anderson, Eric K.; Anderson, William; Baldwin, Brian S.; Baltensperger, David; Barrett, Michael; Blumenthal, Jurg; Bonos, Stacy; Bouton, Joe; Bransby, David I.; Brummer, Charlie; Burks, Pane S.; Chen, Chengci; Daly, Christopher; Egenolf, Josh; Farris, Rodney L.; Fike, John H.; Gaussoin, Roch; Gill, John R.; Gravois, Kenneth; Halbleib, Michael D.; Hale, Anna; Hanna, Wayne; Harmoney, Keith; Heaton, Emily A.; Heiniger, Ron W.; Hoffman, Lindsey; Hong, Chang O.; Kakani, Gopal; Kallenbach, Robert; Macoon, Bisoondat; Medley, James C.; Missaoui, Ali; Mitchell, Robert; Moore, Ken J.; Morrison, Jesse I.; Odvody, Gary N.; Richwine, Jonathan D.; Ogoshi, Richard; Parrish, Jimmy Ray; Quinn, Lauren; Richard, Ed; Rooney, William L.; Rushing, J. Brett; Schnell, Ronnie; Sousek, Matt; Staggenborg, Scott A.; Tew, Thomas; Uehara, Goro; Viands, Donald R.; Voigt, Thomas; Williams, David G.; Williams, Linda; Wilson, Lloyd Ted; Wycislo, Andrew; Yang, Yubin; Owens, Vance (2018-10)
    Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small-scale and short-term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long-term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field-scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm-scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM-ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country.
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    Soil Organic Carbon Isotope Tracing in Sorghum under Ambient CO2 and Free-Air CO2 Enrichment (FACE)
    Leavitt, Steven W.; Cheng, Li; Williams, David G.; Brooks, Talbot; Kimball, Bruce A.; Pinter, Paul J.; Wall, Gerard W.; Ottman, Michael J.; Matthias, Allan D.; Paul, Eldor A.; Thompson, Thomas L.; Adam, Neal R. (MDPI, 2022-02-18)
    As atmospheric carbon dioxide concentrations, [CO2Air], continue their uncontrolled rise, the capacity of soils to accumulate or retain carbon is uncertain. Free-air CO2 enrichment (FACE) experiments have been conducted to better understand the plant, soil and ecosystem response to elevated [CO2], frequently employing commercial CO2 that imparts a distinct isotopic signal to the system for tracing carbon. We conducted a FACE experiment in 1998 and 1999, whereby sorghum (C4 photosynthetic pathway) was grown in four replicates of four treatments using a split-strip plot design: (i) ambient CO2/ample water (365 μmol mol−1, “Control–Wet”), (ii) ambient CO2/water stress (“Control–Dry”), (iii) CO2-enriched (560 μmol mol−1, “FACE–Wet”), and (iv) CO2-enriched/water stressed (“FACE–Dry”). The stable-carbon isotope composition of the added CO2 (in FACE treatments) was close to that of free atmosphere background values, so the subsequent similar 13C-enriched carbon signal photosynthetically fixed by C4 sorghum plants could be used to trace the fate of carbon in both FACE and control treatments. Measurement of soil organic carbon content (SOC (%) = gC/gdry soil × 100%) and δ13C at three depths (0–15, 15–30, and 30–60 cm) were made on soils from the beginning and end of the two experimental growing seasons. A progressive ca. 0.5‰–1.0‰ δ13C increase in the upper soil SOC in all treatments over the course of the experiment indicated common entry of new sorghum carbon into the SOC pools. The 0–15 cm SOC in FACE treatments was 13C-enriched relative to the Control by ca. 1‰, and according to isotopic mass balance, the fraction of the new sorghum-derived SOC in the Control–Wet treatment at the end of the second season was 8.4%, 14.2% in FACE–Wet, 6.5% in Control–Dry, and 14.2% in FACE–Dry. The net SOC enhancement resulting from CO2 enrichment was therefore 5.8% (or 2.9% y−1 of experiment) under ample water and 7.7% (3.8% y−1 of experiment) under limited water, which matches the pattern of greater aboveground biomass increase with elevated [CO2Air] under the Dry treatment, but no parallel isotopic shifts were found in deeper soils. However, these increased fractions of new carbon in SOC at the end of the experiment do not necessarily mean an increase in total SOC content, because gravimetric measurements of SOC did not reveal a significant increase under elevated [CO2Air], at least within the limits of SOC-content error bars. Thus, new carbon gains might be offset by pre-experiment carbon losses. The results demonstrate successful isotopic tracing of carbon from plants to soils in this sorghum FACE experiment showing differences between FACE and Control treatments, which suggest more dynamic cycling of SOC under elevated [CO2Air] than in the Control treatment.