Progress 06/01/10 to 05/31/13
Outputs
Target Audience: The findings from this research program will benefit policy makers, academic community, forest products industry, bioenergy and biofuels industries, crop farmers. The findings of the first component of this research is to determine the amount of sequestration that occurs under switchgrass fields planted for the purposes of providing feedstock for energy production. This information will add to the information already determined by the scientific community on carbon sequestration by warm season grasses. The information will be important to feedstock producers and biorefineries if carbon credits evolve or if need exists to validate production of an advanced fuel occurs. Environmental managers and EPA in particular will also find the information generated from this study important. The findings of the second component of the research will determine biochar’s potential to affect phosphorus/copper behavior in the environment when used as an amendment to soil or other media. This information can assist feedstock producers, the bioenergy industry, the scientific community and environmental managers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? We have several presentations using information collected from the project. Information is moving forward for use in the Integrated Biomass Supply Systems project. Through this grant, two students received a Master degree in Science at the University of Tennessee. Some if the findings were disseminated to Proton Power Inc.’s customers who are interested in pyrolysis system and biochars’ application to soil. We also attended international conferences to present our findings. How have the results been disseminated to communities of interest? Three research papers and two theses have been written and several presentations made. Several other research papers are being prepared and will be submitted for review in the next coming months. Numerous tours of the bioenergy facility containing the pyrolysis system were given to scientists, farmers, legislators, and industries. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Soil samples from switchgrass farms in east Tennessee over a four year period (2008-2011) were collected to determine switchgrass’ ability to sequester SOC. Results showed no differences (P≥0.10) in SOC from 2008-2011 for the 0-5, 15-30, 30-60, and 60-90 cm depths. Significant decreases in the amount of SOC were observed in the 5-10 and 10-15 cm depths. A significant amount of carbon was sequestered in the 90-120 cm depth in the same four year time frame. This shows that through three full growing seasons that switchgrass’ potential to sequester carbon comes at deeper soil depths due to its vast root structure. Overall, through the entire profile, carbon is being sequestered, however, not a significant amount. Greater levels of carbon were present in soil previously no-tilled compared to those previously under conventional tillage, however, neither gained or lost a significant amount of SOC by year four. Alfisols was the only taxonomic category that had a significant increase in SOC by year four. Overall, more carbon was present under Mollisols, but the amount of SOC in year four was not different than that in year one. Greenbeans were the only previously produced crop that did have a significant positive effect on sequestering carbon. SOC amounts tended to slightly decline over the years in the 0-5, 5-10, 10-15, and 15-30 cm depths, but an increase over time in SOC was shown for the 30-60, 60-90, and 90-120 cm depths. Increases in switchgrass yield also corresponded with increased SOC amounts. a: Production and characterization of biochars Biochars produced under various conditions were investigated to determine their chemical/physical/biological properties. Switchgrass biochars were investigated under chemically weathered environment (under different pH conditions) and the release of nutrients and structural changes of the biochars were quantified. In addition, adsorptive characteristics of biochars were characterized for copper and phosphorus in order to investigate the roles of biochars in soil with respect to surface functionality, cation exchange capacity and porosity. Effects of incubation time (time to reach equilibrium), solution pH, quantity of phosphorus in solution, solution ionic strength, and biochar to solution ratio, on phosphorus sorption to biochar were all determined. Sorption maximums for phosphorus on biochars were calculated. Structural changes to biochar after reaching sorptive maximums were analyzed by FTIR (Fourier transform infrared spectroscopy) and XRD (X-ray diffraction). Other researchers and the current study have suggested that the physical and chemical properties of biochar are inconstant when applied to soil and may change depending on environmental factors such as soil pH, time, and the presence of other nutrients in the soil. Therefore, we were interested in determining if previous sorption of phosphorus might affect future behavior of biochar in soil. b: Effects of biochar on bioenergy production and microbial community Soil incorporated with biochars was applied for maximization of bioenergy crops yield (switchgrass and sweet sorghum) in a greenhouse study. Biomass yield (Fig. 1) and chemical composition (ash content and composition, extractives, cellulose, hemicelluloses, lignin, free sugars content) were measured and compared by biochar treatment. Plant growth experiments demonstrated that biochar application increased above-ground biomass yield in both switchgrass and sorghum by up to 25 %. Compositional analysis of sorghum grown in biochar amended soil demonstrated that as the biochar application rate increased the ash content of the plants increased. Response surface regression illustrated that the optimum temperature to produce biochar for soil amendment to maximize plant biomass yield is between 550 to 650 ?C, and that as the application rate increased the plant biomass yield increased. Biochar characteristics resulting in potential carbon sequestration (carbon aromaticity and crystallinity) and improving soil fertility and crop yield (increased ash content and CEC) were identified. It was concluded that switchgrass pyrolyzed at 600 ?C best meets the balance between carbon sequestration and improving soil fertility and plant biomass yield. Finally, studies to determine the impact of biochars on the structure and function of soil microorganisms are complete. The effect of biochar on the quantity and expression of bacterial and archeal genes involved in nitrification are complete. The data are still being analyzed and a complete evaluation of the results will be accomplished in the next 6 months. Biochar addition did not affect nitrification potential. Quantitative real-time PCR (qPCR) analysis indicated that biochar amendment slightly affected the abundance of ammonia monooxygenase genes (amoA) of ammonia-oxidizing bacteria (AOB) but had no effects to amoA genes of ammonia-oxidizing archaea (AOA). Ammonium sulfate addition significantly increased AOB amoA gene copies approximately 2-fold in the soils amended with biochar for either 7 days or 6 months. The amount of amoA genes of AOA was not increased in response to ammonium sulfate treatment. Regarding the expression of amoA, nitrogen fertilization dramatically increased the expression level of amoA genes from AOB (up to 14 fold) but not those from AOA. The increase of AOB amoA gene expression was more significant in soils lacking biochar amendment than in biochar-treated soils (14 versus 9 fold). Addition of biochar to soil did significantly alter the microbial community composition. We conclude that biochar produced from switchgrass pyrolyzed at 800? can sequester C in soil over a long time scale without negatively impacting N transformations.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2010
Citation:
English, Burton C., Potential Economic Impacts to Agriculture if Environmental Services from Agriculture are Recognized, The Role of Agricultural and Forestry in a Reduced Carbon Economy, Ag COnnect Expo, Association of Equipment Manufactures, Orlando, Fl., January 2010.
- Type:
Journal Articles
Status:
Other
Year Published:
2013
Citation:
Charles W. Edmunds, Amy Johnson, Pyoungchung Kim, Arnold M. Saxton, Mark Radosevich, Timothy G. Rials, and Nicole Labb�, The effects of switchgrass-derived biochar application on soil properties and bioenergy crop yield and composition.
- Type:
Journal Articles
Status:
Published
Year Published:
2011
Citation:
P. Kim, A. Johnson, CW. Edmunds, M. Radosevich, F. Vogt, TG. Rials, N. Labb�, Surface functionality and carbon structures in lignocellulosic-derived biochars produced by fast pyrolysis, Energy & Fuels, 25 (10) 4693 - 4703, 2011
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2011
Citation:
P. Kim, CW. Edmunds, N. Labb�, TG. Rials, Effect of pH conditions on nutrients leachability and surface characteristics of biochars. (Presentation). 242nd, ACS meeting, Denver, Co, August 28-Sep. 1, 2011.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2011
Citation:
C. W. Edmunds, N. Labb�, P. Kim, A. Johnson, M. Radosevich, T. Rials. The effects of biochar amendment to soil on bioenergy crop yield and biomass composition. (Poster). 242nd ACS meeting, Denver, Co, August 28-Sep. 1, 2011.
- Type:
Theses/Dissertations
Status:
Other
Year Published:
2012
Citation:
C. W. Edmunds. The effects of biochar amendment to soil on bioenergy crop yield and biomass composition. (Masters Thesis). The University of Tennessee, Knoxville, TN. May 2012.
- Type:
Theses/Dissertations
Status:
Other
Year Published:
2011
Citation:
Soro, Leah Denise, Impact of Switchgrass Bioenergy Feedstock Production on Soil Carbon Dioxide Flux and Below Ground Soil Organic Carbon Storage in East Tennessee, Masters Thesis, University of Tennessee, 2011. http://trace.tennessee.edu/utk_gradthes/1098.
- Type:
Journal Articles
Status:
Other
Year Published:
2013
Citation:
Pyoungchung Kim, Nicole Labb�, Charles W. Edmunds, Amy Johnson, Mark Radosevich, Timothy Rials, Adsorptive properties of Cu (II) on biochars produced from fast pyrolysis.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2012
Citation:
English, B.C., T.E. Yu, J.A. Larson, Getting Liquid Transportation Fuels from Biomass: The UT Experience, College of Agriculture, Environment, and Nutrition Sciences Biomass and Bioenergy Workshop, Tuskegee University, Tuskegee, AL., April 12-13, 2012.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2012
Citation:
English, B.C., Dustin K. Toliver, and Donald D. Tyler, Switchgrass and Carbon Sequestration, Biomass: From Grow to Go, Vonore, TN., October 24, 2012.
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Progress 06/01/11 to 05/31/12
Outputs
OUTPUTS: Biochars produced under various conditions were investigated to determine their chemical/physical/biological properties. Switchgrass biochars were investigated under chemically weathered environment (under different pH conditions) and the release of nutrients and structural changes of the biochars were quantified. In addition, adsorptive characteristics of biochars were characterized for copper and phosphorus in order to investigate the roles of biochars in soil with respect to surface functionality, cation exchange capacity and porosity. Effects of incubation time (time to reach equilibrium), solution pH, quantity of phosphorus in solution, solution ionic strength, and biochar to solution ratio, on phosphorus sorption to biochar were all determined. Sorption maximums for phosphorus on biochars were calculated. Structural changes to biochar after reaching sorptive maximums were analyzed by FTIR (Fourier transform infrared spectroscopy) and XRD (X-ray diffraction). Other researchers and the current study have suggested that the physical and chemical properties of biochar are inconstant when applied to soil and may change depending on environmental factors such as soil pH, time, and the presence of other nutrients in the soil. Therefore, we were interested in determining if previous sorption of phosphorus might affect future behavior of biochar in soil. In parallel, soil incorporated with biochars was applied for maximization of bioenergy crops yield (switchgrass and sweet sorghum) in a greenhouse study. Biomass yield and chemical composition (ash content and composition, extractives, cellulose, hemicelluloses, lignin, free sugars content) were measured and compared by biochar treatment. Finally, studies to determine the impact of biochars on the structure and function of soil microorganisms are complete. The effect of biochar on the quantity and expression of bacterial and archeal genes involved in nitrification are complete. The results have not yet been disseminated or communicated externally. The data are still being analyzed and a complete evaluation of the results will be accomplished in the next 6 months. PARTICIPANTS: Xiuli Dang, a post-doctoral research associate, characterized biochars' ability to sorb and desorb phosphorus and the biochar characteristics which are responsible for these effects. Amy Johnson, co-PI, provided direction and mentoring to X. Dang. Post Doctoral Research Associate Pyoungchung Kim and graduate student Warren Edmunds were supported during the reporting period. Dr Kim investigated the release of nutrient and Cu adsorption while Mr. Edmunds was in charge of the greenhouse study and the characterization of the feedstocks produced with biochars amended soil. Dr Labbe mentored and supervised these tasks. Post Doctoral Research Associate Ying Wang, and two undergraduate students were supported during the reporting period. Dr. Wang conducted the community analyses and quantification assays for nitrification genes with assistance from the undergraduate students. TARGET AUDIENCES: The findings of this research will determine biochar's potential to affect phosphorus/copper behavior in the environment when used as an amendment to soil or other media. This information can assist feedstock producers, the bioenergy industry, the scientific community and environmental managers. If biochar adsorbs appreciable amounts of phosphorus, it can be used to prevent soluble phosphorus loss to the environment. If it is found that sorption is followed by significant desorption of phosphorus, biochar amendments may contain an agronomic benefit by acting as a slow-release fertilizer. At this stage of the work, the primary target audience consists of the larger scientific community engaged in bioenergy and soil science research. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We were able to identify the variables that maximized phosphorus/copper sorption to biochars. Biochars produced at higher pyrolysis temperatures were able to sorb more phosphorus than those produced at lower temperatures. Overall quantities of phosphorus sorption were lower than expected and were considerably lower than sorption to a silt loam soil. Additionally, we examined changes in sorption over a range of pH values which has allowed us to make inferences on the mechanisms of phosphorus sorption. Specifically, it appears that non-specific adsorption, or that adsorption caused by electrostatic forces on the surface of biochar, is occurring. It is likely that this result is due to changes in surface functional groups, a phenomenon which was examined in another part of our overall study. Changes to biochar structure did not appear to take place when biochar was saturated with phosphorus. This implies that phosphorus is not incorporated into mineral structures within or on the surface of biochar and, therefore, will likely not be strongly bound to biochar. These results contribute to our knowledge of biochar properties and will enable an examination of the efficacy of biochar for specific functions such as nutrient retention and contaminant remediation. The addition of biochar to soil was found to have a neglible impact on microbial community structure regardless of the pyrolysis temperature or the amount of biochar added. Addition of biochar had no effect on the abundance of bacterial ammonia monooxygenase (amoA) gene copy number but a significant increase was observed in all treatments that received nitrogen. The abundance of archeal amoA was greater than that of bacterial amoA but did not respond to the addition of biochar or nitrogen. However, expression of both archeal and bacterial amoA was inhibited in soils amended with biochar. The cause of the inhibition is unknown and currently under investigation. Based on feedstock and pyrolysis conditions, biochars with various characteristics can be generated. Our understanding of the effects of the pyrolysis processes and feedstock types on biochar's properties provides us the ability to generate biochars with desired characteristics to improve soil fertility by increasing pH, cation exchange capacity and providing nutrients and carbonaceous pore structures for improving microbial habitat and water retention capacity, which ultimately will enhance nutrient cycling and plant growth. The results of the biochar decomposition study demonstrate that the application of biochar to soil will sequester carbon (C) and allow a bioenergy system to contribute to the environmental sustainability of the feedstock production system and allow the entire system to exist as a C-negative system. By land-applying biochar, soil quality is improved in terms of more efficient C cycling and retention of stable organic matter. Biochars produced at higher temperatures have greater stability in soil and, therefore, will have the largest benefits to sequester C.
Publications
- C. W. Edmunds. The effects of biochar amendment to soil on bioenergy crop yield and biomass composition. (Masters Thesis). The University of Tennessee, Knoxville, TN. May 2012.
- P. Kim, A. Johnson, CW. Edmunds, M. Radosevich, F. Vogt, TG. Rials, N. Labbe, Surface functionality and carbon structures in lignocellulosic-derived biochars produced by fast pyrolysis, Energy & Fuels, 25 (10) 4693 - 4703, 2011.
- P. Kim, CW. Edmunds, N. Labbe, TG. Rials, Effect of pH conditions on nutrients leachability and surface characteristics of biochars. (Presentation). 242nd, ACS meeting, Denver, Co, August 28-Sep. 1, 2011.
- C. W. Edmunds, N. Labbe, P. Kim, A. Johnson, M. Radosevich, T. Rials. The effects of biochar amendment to soil on bioenergy crop yield and biomass composition. (Poster). 242nd ACS meeting, Denver, Co, August 28-Sep. 1, 2011.
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Progress 06/01/10 to 05/31/11
Outputs
OUTPUTS: Biochars produced under different pyrolysis conditions were investigated for soil amendment, especially as nutrient suppliers. Bioenergy crops (switchgrass and sweet sorghum) were grown in the biochar amended soil in a greenhouse study to determine how biochar amendment affects plant growth and composition. Biomass yield and chemical composition (ash content and composition, extractives, cellulose, hemicelluloses, lignin, free sugars content) were measured and compared by biochar treatment. In addition, the release of nutrients under different pH was investigating to assess the amount of nutrient that is available in the biochars. The decomposition of biochars produced at different pyrolysis temperatures in idealized soil environments was examined in a laboratory incubation study. The mineralization of biochar and release of CO2 over time was taken as the decomposition rate. The addition of various rates of nitrogen fertilizer was also investigated in order to determine if an interaction effect between N and biochar-C was present as has been suggested by other researchers. Ongoing work includes studying the sorptive capacity of different biochars for phosphorus and arsenate in order to understand biochar's potential to remove needed nutrients (phosphorus) from soil as well as its potential use as a remediation tool for soils with excessive amounts of either phosphorus or arsenate. Soil samples have been collected in 2008-2011 from 13 sites producing switchgrass for the UT Biofuels Initiative at depths to 4 feet. Chemical analysis of the samples is complete, and has provided extensive data on total carbon. Preliminary analysis and interpretation of the data has begun, and more comprehensive evaluation will continue into next year to define the factors influencing carbon capture by this new bioenergy crop system. PARTICIPANTS: 1) Post-doctoral research associate Pyoungchung Kim generated biochars and characterized their properties. 2) Graduate student Warren Edmunds investigated various biochars as a soil amendment. 3) Nicole Labbe (Co-PI) directed the biochars production, characterization and testing as soil amendment and mentored the post doc and graduate student. 4) Xiuli Dang, a post-doctoral research associate, preformed the incubation experiments and has been investigating the adsorptive properties of biochar under different environmental conditions. 5) Amy Johnson, co-PI, has provided direction and mentoring to X. Dang as well as offering advice and expertise on the overall project. 6) Post Doctoral Research Associate Ying Wang, 7) Meiko Thompson, and 8) Xuili Dong (visiting scholar from China) contributed to the biological experiments of the study. Drs. Thompson and Dang were funded from sources external to the project. Tim Rials has served as project coordinator, and overall project oversight. TARGET AUDIENCES: Target audiences are: Feedstock producers; Bioenergy industry, Scientific community in bioenergy, soil science, life cycle assessment. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Based on feedstock and pyrolysis conditions, biochars with various characteristics can be generated. Our understanding of the effects of the pyrolysis processes and feedstock types on biochar's properties provides us the ability to generate biochars with desired characteristics to improve soil fertility by increasing pH, cation exchange capacity and providing nutrients and carbonaceous pore structures for improving microbial habitat and water retention capacity, which ultimately will enhance nutrient cycling and plant growth. The results of the biochar decomposition study demonstrate that the application of biochar to soil will sequester carbon (C) and allow a bioenergy system utilizing pyrolysis of feedstocks to contribute to the environmental sustainability of the feedstock production system and allow the entire system to exist as a C-negative system. By land-applying biochar, soil quality is improved in terms of more efficient C cycling and retention of stable organic matter. Biochar produced at higher temperatures has greater stability in soil and, therefore, will have the largest benefits to sequestration of soil C. No inhibitory effects of biochar on microbes involved in nitrogen cycling were found. Research has shown that soil carbon accumulation in the switchgrass system is dependent on site and soil taxonomy, and varies predictably with depth. Although analysis has revealed a general increase in total carbon over time, the rate is highly dependent on soil type. Interestingly, carbon buildup appears to be greatest at intermediate depths where root volume is maximized. Work remains focused on generating insight on the belowground ecosystem of switchgrass.
Publications
- P. Kim, A. Johnson, CW. Edmunds, M. Radosevich, F. Vogt, TG. Rials, N. Labbe, Surface functionality and carbon structures in lignocellusic-derived biochars produced by fast pyrolysis, Energy & Fuels, 25 (10) 4693 - 4703, 2011
- P. Kim, CW. Edmunds, N. Labbe, TG. Rials, Effect of pH conditions on nutrients leachability and surface characteristics of biochars. (Presentation). 242nd, ACS meeting, Denver, Co, August 28-Sep. 1, 2011.
- C. W. Edmunds, N. Labbe, P. Kim, A. Johnson, M. Radosevich, T. Rials. The effects of biochar amendment to soil on bioenergy crop yield and biomass composition. (Poster). 242nd ACS meeting, Denver, Co, August 28-Sep. 1, 2011.
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