2008 Annual Report
NP 204, Component I: Carbon Cycle and Carbon Storage - Organic Carbon Transformations. Our research 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. We are also investigating the effects of carbon dioxide on changes in plant structure and subsequent impacts on decomposition (e.g., microbial processes), and soil carbon storage. Soil carbon data from the first four years of the cropping systems study have been published; the remaining six years of data have been collected and are being processed. Soil carbon data have also been collected from the pasture study. Carbon dioxide efflux from both systems continues to be monitored as does carbon flow through soil water.
NP 204, Component II: Trace Gases - Cropping Systems; Rangelands, Pastures and Wetlands. Our research addresses the impacts of elevated carbon dioxide within conservation vs. conventional cropping systems as well as under differing pasture management practices (nitrogen) on trace gas (carbon dioxide, nitrous oxide, and methane) efflux from soil. Trace gases were monitored throughout the final year of the cropping systems study; a publication on the results is in internal review. Trace gases have also been monitored throughout the pasture study; samples are being analyzed and data summarized.
NP204, Component III: Agricultural Ecosystem Impacts - Cropping Systems; Grazinglands (Range and Pastures). Our research involves measurement of plant responses (above and below the ground) in conventional vs. conservation cropping systems and within improved vs. unimproved pastures with increasing atmospheric carbon dioxide and the ability of these systems to assist in mitigation of this rise via soil carbon sequestration. The final year of the cropping systems study was completed. Aboveground biomass data have been collected and analyzed; root data are being processed; soil physicochemical properties, including soil carbon are being assessed. Aboveground pasture biomass data have been collected and analyzed; soil cores for root and soil carbon have been collected and are being processed. Minirhizotron and soil nutrient data continue to be collected and processed.
Invasive weeds can impact biodiversity and cost billions of dollars each year in control and lost productivity. Understanding how the rising level of carbon dioxide may alter establishment, spread, and control of invasive weeds will be crucial to future management strategies. Purple (Cyperus rotundus) and yellow (C. esculentus) nutsedge and Chinese privet (Ligustrum sinense) had more biomass when grown under elevated carbon dioxide, suggesting that these invasive weeds will present agricultural producers with even greater problems as atmospheric carbon dioxide continues to rise.
This accomplishment addresses Global Change National Program (NP204), Agricultural Ecosystem Impacts, Problem Area 4. Pests.2. Analyzed nutrient composition of crop tissue grown under elevated atmospheric carbon dioxide and no-tillage management.
The quantity and quality of plant tissue may impact feed quality and nutrient cycling in a future, high CO2 world. The findings of this research showed that high CO2 increased nutrient content (e.g., N, P, K), especially in grain. This increase was greater for soybean (Glycine max) than for sorghum (Sorghum bicolor). Crop residues (stover and roots), which become nutrient inputs to the soil, showed similar increases in nutrient content but were more variable than grain. Predictions of nutrient outputs under future, high CO2 conditions will be more reliable than those associated with nutrient inputs to the soil from crop residues.
This accomplishment addresses Global Change National Program (NP204), Agricultural Ecosystem Impacts, Problem Area 2. Cropping Systems.3. Determined the impact of elevated atmospheric carbon dioxide on soil carbon dynamics.
Increasing atmospheric CO2 has led to concerns about changes in the global environment and, in particular, how increased crop growth may impact the buildup of soil organic matter. Two years of free-air CO2 enrichment led to more soil carbon storage in a sorghum production system regardless of irrigation regime. Increased biomass production, from growth in high CO2, suggests more carbon input to soil which can improve soil quality as well as help mitigate the rise in atmospheric carbon dioxide.
This accomplishment addresses Global Change National Program (NP204), Carbon Cycle and Carbon Storage, Problem Area 8. Interactions of Carbon and Nitrogen Cycles.
5.Significant Activities that Support Special Target Populations
We have recently initiated investigations into alternative crops (sweet potato, cassava, and kudzu) which small farmers might grow, with little input, for ethanol production.
Prior, S.A., Runion, G.B., Rogers Jr, H.H., Torbert III, H.A. 2008. Effects of atmospheric CO2 enrichment on crop nutrient dynamics under no-till conditions. Journal of Plant Nutrition. 31(4):758-773.
Prior, S.A., Torbert III, H.A., Runion, G.B., Rogers Jr, H.H., Kimball, B.A. 2008. Free-air CO2 enrichment of sorghum: Soil carbon and nitrogen dynamics. 37:753-758.
Rogers Jr, H.H., Runion, G.B., Prior, S.A., Price, A.J., Torbert III, H.A., Gjerstad, D.H. 2008. Effects of elevated atmospheric CO2 on invasive plants: Comparison of purple and yellow nutsedge (Cyperus rotundus L. and C. esculentus L.). Journal of Environmental Quality. 37:395-400.
Smith, K.E., Runion, G.B., Prior, S.A., Price, A.J., Rogers Jr, H.H., Torbert III, H.A. 2008. Chinese privet (Ligustrum sinenese) in an elevated CO2 environment. Botany Research Journal. 1:43-48.
Kang, H., Shannon, D.A., Prior, S.A., Arriaga, F.J. 2008. Hedgerow pruning effects on light interception, water relations and yield in alley cropped maize. Journal of Sustainable Agriculture. 31(4):115-137.
Kornecki, T.S., Prior, S.A., Runion, G.B., Rogers Jr, H.H., Erbach, D.C. 2008. A hydraulic core extraction-cutting device for soil-root studies. Communications in Soil Science and Plant Analysis. 39:1080-1089.