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United States Department of Agriculture

Agricultural Research Service

Research Project: GLOBAL CHANGE AND BELOWGROUND PROCESSES IN AGRICULTURAL SYSTEMS

Location: National Soil Dynamics Laboratory

2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The major problem this work is helping to resolve is that of global environmental change. This work seeks to understand key belowground responses to atmospheric carbon dioxide concentration (an important aspect of global change) and carbon dynamics and storage within agricultural systems. The National Research Council Plan for Action proposes a major objective "to determine how interactions between elevated carbon dioxide and temperature, water, and nutrients affect belowground processes." Carbon storage in terrestrial sinks such as agricultural systems is of international significance in light of issues related to the Kyoto Protocol which seeks to control carbon emission (based on predictions of greenhouse gases causing changes in climate).

The project objectives are to reduce uncertainty regarding: (1) the effects of rising atmospheric carbon dioxide concentration on crop production and food security; and (2) the role of agronomic systems in the storage of atmospheric carbon dioxide by soil. Specifically, the research is designed to determine effects of atmospheric carbon dioxide level on belowground processes which control crop productivity and nutrient cycling, including structure and function of root systems, soil microorganisms, soil carbon and nitrogen changes, and other soil responses.

This research addresses several components under National Program 204 - Global Change. Component I: Carbon Cycle and Carbon Storage, Problem Area A. Cropping Systems and Tillage. Our research addresses agricultural practices and cropping systems (e.g., conservation vs. conventional) that promote soil carbon storage and the impacts of global change (i.e., elevated carbon dioxide) on soil carbon storage within these systems. Component I: Carbon Cycle and Carbon Storage, Problem Area E. Organic Carbon Transformations. Global change research at the USDA-ARS National Soil Dynamics Laboratory (NSDL) is seeking to understand factors controlling rate, mass, and timing of carbon dioxide sequestered; fate of carbon within the soil; rate of production and turnover of soil carbon pools; and processes and mechanisms of soil carbon loss. The effects of carbon dioxide on changes in plant structure and subsequent impacts on decomposition (e.g., microbial processes), and soil carbon storage are also being investigated. Component III: Agricultural Ecosystems, Problem Area A. Cropping Systems. Our research directly involves measurement of plant responses (above and below the ground) to multiple interactions of abiotic and biotic stresses with rising carbon dioxide.

"Human activities are currently leading to changes in the global environment at virtually unprecedented rates...increases in carbon dioxide and other greenhouse gases...have captured the attention of scientists, the public, and policymakers. The problem of global environmental change is crucial and urgent," (Committee on Global Change 1988). "Industrial, agricultural, and other human activities, coupled with an expanding world population, are contributing to processes of global change that may significantly alter the Earth habitat...Development of effective policies to abate, mitigate, and cope with global change will rely on greatly improved scientific understanding of global environmental processes," (Global Change Research Act of 1990). Reducing uncertainty regarding the effects of rising atmospheric carbon dioxide concentration on crop production and food security is important to agricultural producers and consumers alike. Understanding the role of agronomic systems in the storage of atmospheric carbon dioxide by soil is also crucial to the global population in terms of lessening the potential climatic effects of global change. The ultimate goal of this research is to provide knowledge for the management of soil-plant-atmospheric relationships in a changing global environment.


2.List by year the currently approved milestones (indicators of research progress)
The current Plan received OSQR approval on 02/04/2005 and is scheduled to occur from FY 2005 through FY 2009; the following are the milestones listed for this Plan:

Objective 1 - Determine the effects of elevated atmospheric carbon dioxide and agricultural systems - row crops and pastures - on selected belowground characteristics of the systems, including roots (structure and function), soil microorganisms (populations and activity), and soil (carbon, nitrogen, and water)

a. root biomass cores with associated aboveground plant harvests - cropping systems and pasture studies b. analysis and publication of biomass data - both studies c. minirhizotron data collection and analysis - both studies d. analysis and publication of minirhizotron data - both studies e. soil moisture monitoring using Time Domain Reflectometry (TDR) - both studies f. root hydraulic conductance and stem flow measurements in the cropping system study g. root hydraulic conductance pasture study h. analysis and publication of root hydraulic conductance and stem flow data -both studies i. microbial biomass, activity, community structure, and mycorrhizae work - both studies j. analysis and publication of microbial and mycorrhizal data - both studies k. soil C and N determinations - both studies l. analysis and publication of soil C and N data - both studies m. C and N determinations in lysimeter solution water - both studies n. analysis and publication of soil solution C and N data - both studies

Objective 2 - Determine the effects of elevated atmospheric carbon dioxide and crop system management - row crops or pasture - on plant-soil relationships that impact soil physicochemical properties

a. C, N, and other nutrient concentrations in residues - both studies b. determination of tissue carbohydrates - both studies c. analysis and publication of tissue quality data - both studies d. litter bag decomposition - both studies e. analysis and publication of litter bag decomposition data - both studies f. laboratory determinations of soil C and N mineralization - both studies g. analysis and publication of soil C and N mineralization data - both studies h. C, N, and other nutrient concentrations in soils - both studies i. analysis and publication of soil nutrient stratification data - both studies j. determination of C and N in soil aggregate fractions - both studies k. analysis and publication of soil aggregate fraction C and N data - both studies l. determination of water infiltration using rainfall simulators - both studies m. determination of soil physical properties - both studies n. analysis and publication of data on soil physical properties - both studies

Objective 3 - Determine the effects of elevated atmospheric carbon dioxide and crop system management - row crops or pasture - on efflux of three major greenhouse trace gases (carbon dioxide, nitrous oxide, and methane) from soil

a. collection of soil carbon dioxide, nitrous oxide, and methane efflux data - both studies b. analysis and publication of soil trace gas efflux data - both studies


4a.List the single most significant research accomplishment during FY 2006.
Increasing atmospheric carbon dioxide concentration has led to concerns about potential changes to production agriculture as well as agriculture's role in storing this extra carbon. We have completed eight years in a long-term (10 year) study comparing "conventional" tillage (using a grain sorghum and soybean rotation) with winter fallow and a "conservation" system (using the same primary row-crop rotation) with no tillage and winter cover crops (crimson clover, sunn hemp and wheat) on a Decatur silt loam soil within the soil bin facilities of the NSDL, Auburn, AL. Sorghum has been recently planted. Crops of soybean and clover have been harvested; associated data on above- and belowground plant growth and physiology have been collected for analysis. Results suggest that with conservation management in an elevated carbon dioxide environment, greater residue amounts could increase soil carbon storage as well as increase groundcover for increased soil moisture retention and reduced erosion.


4b.List other significant research accomplishment(s), if any.
Elevated atmospheric carbon dioxide is known to increase growth of most plant species. However, little is known about the effects of additional carbon dioxide on invasive weeds. Plant biomass was determined for six invasive weeds important to agriculture in the southeastern US. Elevated carbon dioxide increased biomass for all species with data following typical patterns for C3 vs. C4 response. This research suggests that invasive species will thrive under high carbon dioxide and highlights the need for similar work with other important invasive weeds, as well as research on competitive effects between crops and their associated weeds under elevated carbon dioxide. These findings are important to both producers and policy-makers interested in developing appropriate control strategies under a changing environment.

Research on belowground processes requires development of novel techniques and methodologies to reduce time and labor spent on these efforts as well as to improve measurement accuracy. A novel, non-destructive soil carbon analyzer using inelastic neutron scattering continues to be tested in cooperation with Brookhaven National Laboratory against standard soil coring and soil excavation techniques. The new analyzer produced qualitative results comparable with the standard techniques on several different soil types; further research is planned to address quantitative aspects of this new analyzer and application methods to enhance its mobility for use under various field situations (e.g., forest, row crop, and pasture). This new method shows promise for facilitating rapid assessment of soil carbon dynamics.


4c.List significant activities that support special target populations.
Global change research at the NSDL will impact producers of agronomic commodities, including small farmers, and will provide information on global change impacts on crops and their implications for future food security. In addition, this research will aid the global population through greater understanding of means to increase carbon storage in soils and, thus, help reduce the rising atmospheric carbon dioxide concentration.


5.Describe the major accomplishments to date and their predicted or actual impact.
Research from this team has shown conclusively that elevated atmospheric carbon dioxide can cause significant changes in plant root structure and function; often the largest increase in plant growth under elevated atmospheric carbon dioxide occurs in belowground tissues. These results imply a greater ability of plant root systems to explore the soil for needed nutrients and water. Research which began in controlled environments was carried into open field carbon dioxide experiments. Extensions of this work have shown changes in plant tissue quality which affect decomposition and soil carbon and nitrogen, improvement of groundwater quality, and shifts in root-zone microbiology (populations and activity) in carbon dioxide-enriched agricultural systems. The current research project, which involves the longest-running elevated carbon dioxide experiment examining differences in cropping systems management, indicates that agricultural management strategies (including conservation tillage systems) can be developed which can more fully utilize the increasing carbon dioxide in the earth's atmosphere and that these systems have the potential to sequester more of this carbon in the soil. Research from this project represents the primary research effort into belowground effects of elevated carbon dioxide in agro-ecosystems. The newly initiated southeastern pasture study represents the first known effort at examining this prevalent system type under carbon dioxide exposure in a field situation. Research has been expanded, via extramural funding, to examine the impacts of elevated carbon dioxide on invasive weeds important to southeastern agricultural systems. Results have been sought by research organizations (both public and private), action agencies, and by decision making institutions. The work has been widely accepted in the U.S. and abroad, used by action agencies (e.g., DOE and EPA) and published results are frequently quoted.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
Data sets, interpretations, and publications have been provided to researchers in the public and private sectors including national laboratories (Lawrence Livermore, Oak Ridge, Argonne, and Brookhaven): universities; book authors; the Smithsonian Institution; the Intergovernmental Panel on Climate Change, Global Change and Terrestrial Ecosystems of the International Geosphere-Biosphere Programme; and to various agencies (DOE, EPA, NASA, NSF, U.S. Fish and Wildlife Service, U.S. Global Change Research Program, and National Institute for Global Environmental Change). Descriptions and implications of our global change research projects have been provided to various individuals and groups visiting the National Soil Dynamics Laboratory. Presentations of research finding by NSDL global change scientists have been made to various groups (e.g., Alabama Farmers Federation; Southeast Regional Center of the National Institute for Global Environmental Change; Agronomy Society of America; Crop Science Society of America; Soil Science Society of America; USDA-NRCS National Agronomy Meeting Greenhouse Gas Reduction through Agricultural Carbon Enhancement Network; Southern Conservation Tillage Systems Conference; DOE Workshop on Emerging Modalities for Soil Carbon Analysis: Sampling Statistics and Economics; Society for Range Management; and at other regional, national, and international meetings, workshops, and conferences).

Results of our global change work (with regard to interactions between plants, soil, and the atmosphere) continue to be published in a timely fashion; these efforts add to existing knowledge which will lead to improvements in crop productivity and sound farm management practices in a changing environment. Results explaining plant responses (especially belowground) to increased amounts of carbon dioxide in the atmosphere and management of carbon storage in agricultural systems (to lessen future impacts of the greenhouse effect) continue to be made available to other scientists and policymakers.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Soil carbon dioxide efflux research from the NSDL Global Change Program will be highlighted in an article titled, "What Goes Up? Measuring Air and Soil Carbon Exchange from Conservation Cropping Systems" in the August, 2006 issue of the USDA-ARS popular magazine, "Agricultural Research".

A Proceedings article was published from a presentation on tillage effects on N mineralization and losses of winter applied manure at the 28th Annual Southern Conservation Systems Conference, June 26-28, Amarillo, TX. A Proceedings article will be published from a presentation on the effects of atmospheric carbon dioxide enrichment on crop nutrient dynamics under no-till conditions at the 17th International Conference of the International Soil Tillage Research Organization. August 28-September 3, Kiel, Germany. A presentation on growth increases in the invasive weed tropical spiderwort under elevated atmospheric carbon dioxide was made at the 38th American Peanut Research and Education Society Meeting, July 11-14, Savannah, GA.

A presentation on growth responses of the invasive weed tropical spiderwort to elevated atmospheric carbon dioxide was made at the Southern Branch Meeting of the Agronomy Society of America, February 5-7, Orlando, FL.

A presentation on soil carbon analysis in large fields using a scanning system was made at the DOE sponsored "Emerging Modalities for Soil Carbon Analysis: Sampling Statistics and Economics Workshop", January 19-20, Upton, NY.

A presentation on the effects of elevated atmospheric carbon dioxide on tropical spiderwort was made at the Symposium on Tropical Spiderwort (Commelina benghalensis): An Exotic Invasive Weed in the Southeast US. November 29, 2005, Tifton, GA.


Review Publications
Derner, J.D., Schuman, G.E., Jawson, M.D., Shafer, S.R., Morgan, J.A., Polley, H.W., Runion, G.B., Prior, S.A., Torbert Iii, H.A., Rogers Jr, H.H., Bunce, J.A., Ziska, L.H., White, J.W., Franzluebbers, A.J., Reeder, S.J., Venterea, R.T., Harper, L.A. 2005. USDA-ARS global change research on rangelands and pasturelands. Rangelands. 27(5):36-42.

Prior, S.A., Runion, G.B., Rogers Jr, H.H., Conn, J.S., Cochran, V.L. Atmospheric co2 enrichment of potato in the subarctic: root distribution and soil biology. Environmental Control in Biology. 43(3):165-172.

Prior, S.A., Runion, G.B., Kornecki, T.S., Rogers Jr, H.H. 2006. A pneumatic device for lifting containers in plant water use studies. Agronomy Journal. 98:120-123.

Prior, S.A., Torbert III, H.A., Runion, G.B., Rogers Jr, H.H., Ort, D.R., Nelson, R.L. 2006. Free-air carbon dioxide enrichment of soybean: Influence of crop variety on residue decomposition. Journal of Environmental Quality. 35:1470-1477.

Pritchard, S.G., Prior, S.A., Rogers Jr, H.H., Davis, M.A., Runion, G.B., Popham, T.W. 2006. Effects of elevated atmospheric co2 on root dynamics and productivity of sorghum grown under conventional and conservation agricultural management practices. Agriculture, Ecosystems and Environment. 113:175-183.

Runion, G.B., Davis, M.A., Pritchard, S.G., Prior, S.A., Mitchell, R.J., Torbert III, H.A., Rogers Jr, H.H., Dute, R.R. 2006. Effects of elevated atmospheric co2 on biomass and carbon accumulation in a model regenerating longleaf pine community. Journal of Environmental Quality. 35:1478-1486.

Rogers Jr, H.H., Pritchard, S.G., Davis, M.A., Prior, S.A., Runion, G.B., Torbert III, H.A., Mitchell, R.J. Carbon storage and cycling, soil microbiology, and water quality in co2-enriched agro-ecosystems. Final Techinical Reprt, Terrestrial Carbon Processes (TCP) Program of the Office of Science, Biological and Environmental Research (BER), U. S. Department Of Energy Annual Report, Germantown, MD. 7 p.

Prior, S.A., Price, A.J., Runion, G.B., Rogers Jr, H.H., Gjerstad, D.H., Torbert III, H.A. 2006. Growth response of the invasive weed tropical spiderwort to elevated atmospheric co2 [abstract]. American Society of Agronomy Branch Meeting. 2006 CDROM.

Wielopolski, L., Mitra, S., Zhang, Y., Torbert III, H.A., Prior, S.A. 2006. Soil carbon analysis in large fields using a scanning system [abstract]. Emerging Modalities for Soil Carbon Analysis: Sampling Statistics and Economics Workshop.

Price, A.J., Prior, S.A., Runion, G.B., Stoll, M.E., Van Santen, E., Rogers Jr, H.H., Gjerstad, D.H., Torbert III, H.A. 2006. Effects of elevated atmospheric co2 on tropical spiderwort [abstract]. Symposium on Tropical Spiderwort (Commelina benghalensis): An Exotic Invasive Weed in the Southeast U.S.

Price, A.J., Runion, G.B., Prior, S.A., Rogers Jr, H.H., Torbert III, H.A., Gjerstad, D.H. 2006. The invasive weed tropical spiderwort increases growth under elevated atmospheric co2 [abstract]. Symposium on Tropical Spiderwort: A New Troublesome Exotic-Invasive Weed in Peanut. 38th American Peanut Research and Education Society. Paper No. 119. p. 82.

Last Modified: 7/28/2014
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