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United States Department of Agriculture

Agricultural Research Service

Research Project: SOIL ORGANIC MATTER AND NUTRIENT CYCLING TO SUSTAIN AGRICULTURE IN THE SOUTHEASTERN USA
2010 Annual Report


1a.Objectives (from AD-416)
Generally, we are designing crop and animal management strategies based on sound biogeochemical principles, that are profitable, and have positive environmental impacts. Specifically, we are developing strategies based on experiments evaluating tillage and cover crop management, crop selection and productivity, forage quality and availability, plant genetics, grazing pressure, animal health and productivity, animal manure application, nutrient cycling, soil quality, carbon storage, and water runoff and quality.


1b.Approach (from AD-416)
To be able to simultaneously address production and environmental issues, we are taking a multidisciplinary approach to.
1)understand biogeochemical mechanisms and processes involved in water and nutrient cycles,.
2)evaluate alternative management options and.
3)develop management systems to improve the sustainability of agriculture in the region. This requires both field and laboratory investigations, including fescue toxicosis effects on animal physiology. Several field studies will give long-term perspectives and yield realistic relationships between productivity and environmental health cropping studies include:.
1)water catchments receiving poultry litter with different tillage management and.
2)cover cropping trials based on plant species and method and timing of killing. Pasture studies include.
1)evaluation of grazing pressure and organic-inorganic fertilization on soil organic C storage, nutrient runoff, and productivity and.
2)water catchments with differences in endophyte association, organic-inorganic fertilization, and presence of cattle.


3.Progress Report
Soil, plant, animal, and water responses are being collected and evaluated. Botanical composition, forage availability, and cattle performance during the first 6 years of experimentation have been summarized in a publication (Franzluebbers et al., 2009; Forage Grazinglands doi:10.1094/FG-2009-0227-01-RS). Water samples have been collected following storm events. Laboratory processing of the extensive sampling (420 sites x 2 depths) to determine spatial variation of soil properties has been completed and will be statistically analyzed and peer-reviewed reports will be prepared in coming months. A few analyses remain to be completed to be able to analyze and prepare peer-reviewed reports on the temporal changes in soil organic carbon (C) and various soil quality properties and processes, but these analyses should be completed by the end of the 2010 calendar year. A one-year no-cost extension was granted to the investigators from the USDA National Institute for Food and Agriculture administration to complete the analyses that remain.


4.Accomplishments
1. Organic Carbon can be Sequestered in Soils of the Southeastern United States of America (USA) with Conservation Agricultural Management. Soils of the southeastern USA have been degraded by tillage practices that have resulted in loss of topsoil and fertility but conservation agricultural management has the potential to rebuild soil fertility, restore soil functions, mitigate greenhouse gas emissions, and increase surface-soil organic matter. A scientist from the United States Department of Agriculture (USDA) Agricultural Research Service in Watkinsville Georgia synthesized recent literature from the southeastern USA to estimate carbon sequestration rates with conservation management, evaluate the relationship of surface-soil organic carbon to soil functions, and recommend soil sampling strategies to improve the detection of soil organic carbon sequestration. Surface accumulation of soil organic carbon was common under conservation agricultural management and appears to be linked to the rate of soil organic carbon sequestration, abatement of erosion, and improvement in water quality. With 111 million acres of agricultural land in the southeastern USA, 113 million tons of carbon dioxide per year was estimated as potentially sequestered in soil organic matter with conservation management. These results are valuable for state and federal conservation agencies seeking to promote conservation practices since landowners in the southeastern USA could potentially restore soil fertility and mitigate greenhouse gas emissions.

2. Soil Conditioning Index has been Calibrated to Soil Organic Carbon in the Southeastern United States of America (USA). Rapid and reliable assessments of the potential of agricultural management systems to sequester soil organic carbon are needed to promote conservation and mitigate greenhouse gas emissions. A collaborative effort to investigate the validity of the soil conditioning index for prediction of soil organic carbon sequestration was developed among scientists with ARS in Watkinsville, Georgia, a former ARS research associate in Beltsville, Maryland (now at the National University in Asuncion, Paraguay), and with Natural Resource Conservation Service (NRCS) in Temple Texas. Published measurement of soil organic carbon from various studies throughout the southeastern USA were compared with computer simulations of soil organic carbon based on the soil conditioning index and the Revised Universal Soil Loss Equation. Within a field study, the soil conditioning index was usually highly related to soil organic carbon content. Across studies, soil organic carbon content would increase by 0.25 tons of carbon dioxide per acre per year per unit change in Soil Conditioning Index (SCI). These results will have important implications for farmers, crop advisors, scientists, and policy makers interested in carbon trading schemes throughout the 300 million acres of land in the southeastern USA.

3. Soil Microbial Diversity can be Restored with Prairie Restoration. There is great diversity of microorganisms in soil and little is known about how cultivation and restoration of native prairie may alter the composition and genetic diversity of bacteria and fungi in soil. A collaborative research effort among scientists at the University of Georgia, Mississippi State University, Kansas State University, and (United States Department of Agriculture) USDA-Agricultural Research Service in Watkinsville Georgia was developed to test for an effect of cultivation versus restoration of native prairie on soil microbial diversity in soils from the Konza Prairie Biological Station near Manhattan, Kansas. Soil organic carbon and nitrogen content simply increased with increasing years of grassland restoration. However, the soil microbial community during restoration was a transitional bacterial community that differed from either the highly disturbed cropland or the undisturbed original prairie. These results have important implications for the preservation of global genetic diversity and mitigating the impact of agriculture on the environment.

4. Soil carbon sequestration in United Stated of America (USA) agricultural systems is reviewed. Reducing atmospheric greenhouse gases has been identified as one of the most pressing current environmental issues. In agricultural systems, the sequestration of carbon in soils is thought to be one of the best options for reducing atmospheric concentrations of the greenhouse gas, carbon dioxide. A review article was prepared by scientists from the USDA-Agricultural Research Service in Fort Collins, Colorado, Gainesville Florida, Cheyenne, Wyoming, and Watkinsville, Georgia, as well as from Colorado State University and the USDA-Natural Resources Conservation Service in Davis, California and Lincoln Nebraska. The work described the potential of agriculture in the USA to mitigate climate change, primarily through soil carbon sequestration, and also identified critical gaps areas where further research is needed to enhance carbon sequestration capability in cropping systems, grazinglands, agroforestry, horticulture, and turfgrass. The information provides a useful synthesis for policy makers and researchers working to optimize agricultural carbon sequestration and direct further research needed to move forward with an effective carbon sequestration strategy for agriculture.


5.Significant Activities that Support Special Target Populations
Most forage/livestock operations in the Southern Piedmont are owned by small-farm producers with gross receipts well under $250,000. We are developing conservation agricultural systems appropriate for use by these small-farm producers, including no-tillage planting, cover cropping, land application of manures, and crop-livestock integration.


Review Publications
Franzluebbers, A.J. 2010. Achieving soil organic carbon sequestration with conservation agricultural systems in the southeastern USA. Soil Science Society of America Journal. 74(2):347-357.

Morgan, J.A., Follett, R.F., Allen Jr, L.H., Del Grosso, S.J., Derner, J.D., Dijkstra, F.A., Franzluebbers, A.J., Fry, R., Paustian, K., Schoeneberger, M.M. 2010. Carbon sequestration in agricultural lands of the United States. Journal of Soil and Water Conservation. 65(1):6A-13A.

Franzluebbers, A.J., Causarano, H.J., Norfleet, M.L. 2010. Calibration of the soil conditioning index (SCI) to soil organic carbon in the southeastern USA. Plant and Soil Journal. DOI:10.1007/s11104-010-0310-9.

Jangid, K., Williams, M.A., Franzluebbers, A.J., Blair, J.M., Coleman, D.C., Whitman, W.B. 2009. Development of soil microbial communities during tallgrass prairie restoration. Soil Biology and Biochemistry. On-Line. 42:302-312.

Last Modified: 4/16/2014
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