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United States Department of Agriculture

Agricultural Research Service

2009 Annual Report

1a.Objectives (from AD-416)
1. Determine how crop, biomass and soil management practices alter the rate at which carbon and nitrogen are stored in soil or released as greenhouse gas emissions to develop economically viable practices that enhance storage and minimize emissions particularly in the cool, wet, glacial-till soils in the north Central United States. 2. Evaluate impacts of global environmental changes on traditional, biofuel and alternative crops.

1b.Approach (from AD-416)
Carbon cycling will be conducted as part of a national monitoring effort (GRACEnet). Soil physical, chemical and biological factors, and crop inputs will be monitored over time. Established long-term field experiments will be continued to assess impact of tillage method on carbon storage, trace gas emission and economic yield. The active, transitional and passive pools will be assessed in the tillage treatments to determine the rate and direction of change in the various pools. On-farm research is comparing the impact of high manure application on gas exchange monitored by eddy covariance and monitoring the nutrient content of tile water samples. Economic analysis will be conducted to evaluate the economic returns for the different residue removal/tillage combinations. Field experiments will be conducted to obtain plant parameters from a range of species and management systems. The plant data will be integrated with the soil carbon data to statistically model dynamics of C inputs and subsequent changes in carbon pools. Plant information will be collected from growth chamber and/or greenhouse experiments utilizing controlled conditions to mimic desired environmental stresses.

3.Progress Report
This research has two general objectives: first to ascertain how agricultural management impacts greenhouse gas emission (N2O, CH4 and CO2) and carbon storage; second, to measure how global climate change may impact agricultural crops. The overall goal is to develop agricultural management systems that can readily adapt to climate change and to mitigate greenhouse gas accumulations. To achieve these objectives multiple experiments are being conducted to compare management and crops. Comparison of greenhouse gas emission among the first set of scenarios has been completed; the emission data was presented at a national meeting and the first manuscript was accepted by a peer-reviewed journal. We completed the collection of greenhouse gas emission data from organically- and conventionally-managed plots, and data analysis is in progress. We are in the second year of collecting greenhouse gas emission data from plots with and without corn stover harvest, and in the first year of collecting emission data from an experiment studying the impact of crop rotation and perennials on soil carbon storage. This latter experiment was modified to include biomass harvest coupled with cover crops. Above-ground yields and root production were monitored.

Crops were grown in growth chambers under "ideal" conditions to serve as a reference to crops subjected to single or multiple stresses (e.g., inadequate moisture). Sugar beets were sampled in a farmer’s field at several growth stages and its sugar content determined. Sugar beet will be used as an energy reference for other crops. Chemical and statistical analyses already performed on two-year data for all crops and data on wheat was used to develop crop coefficients. Models were developed for bread and durum wheat and a manuscript was accepted for publication. New data is currently being collected and will be collated with previous years' data for final analyses and modeling. Field experiments were repeated as planned, adding sweet sorghum (a potential bioenergy feedstock). Crop and soil samples were collected, and analysis is in progress. Plant sampling was adjusted to account for differences in growth and development caused by environmental conditions. Three samplings will be conducted at the end of vegetative growth, reproductive and physiological maturity stages for each crop and treatment. Data from the previous two years was used to develop crop coefficients, and it is being collated with this year’s data for statistical analyses and to prepare a manuscript. Genotypic differences and genetic potential in switchgrass for photosynthetic acclimation to temperature fluctuations and avoidance of carbohydrate feedback inhibition of productivity was presented at a professional meeting and the manuscript is in progress.

1. Greenhouse gas emission from contrasting management scenarios in the northern Corn Belt. There is a need to identify and develop management options that minimize greenhouse gas emission (nitrous oxide, methane) and/or store more carbon in soil as a means to improve environmental quality without loss of productivity or profitability. A three-year study was completed. Results of the greenhouse gas emission study were presented at a national professional meeting and accepted for publication in a peer-reviewed journal. Negligible amounts of methane were released from the soil; most of the nitrous oxide was emitted during spring thaw, with little or no difference among traditional and alternative practices, but varied by year and crop. This work provides guidance to producers, scientists, and policy-makers for developing agricultural systems that mitigate global warming risks without sacrificing productivity or profitability.

2. Modeling biomass allocation and grain yield in wheat under abiotic stress. Abiotic stress caused by shorter growing seasons, competition for limited water resources, or both, are expected to impact wheat production. Models were developed to quantitatively relate grain yield of bread and durum wheat to dry matter partitioning in response to abiotic stress from shorter growing seasons and larger competition for resources during two years of contrasting growing conditions. The models were accepted for publication in a peer-reviewed journal. The information will assist wheat breeders and plant physiologists in identifying genetic resources of and deploying adaptive phenological and morphological traits to tolerate abiotic stress.

Review Publications
Pikul, Jr., J.L., Chilom, G., Rice, J., Eynard, A., Schumacher, T.E., Nichols, K., Johnson, J.M.F., Wright, S., Caesar, T., Ellsbury, M. 2009. Organic Matter and Water Stability of Field Aggregates Affected by Tillage in South Dakota. Soil Science Society of America Journal. 73:197-206.

La Scala, N., Lopes, A., Spokas, K.A., Archer, D.W., Reicosky, D.C. 2009. Short-Term Temporal Changes of Bare Soil CO2 Fluxes Described by First-Order Decay Models. European Journal of Soil Science. 60(2):258-264.

Pikul Jr, J.L., Johnson, J.M., Schumacher, T., Vigil, M.F., Riedell, W.E. 2008. Change in Surface Soil Carbon Under Rotated Corn in Eastern South Dakota. Soil Science Society of America Journal. 72:1738-1744.

Halvorson, A.D., Johnson, J.M. 2009. Cob Characteristics in Irrigated Central Great Plains Studies. Agronomy Journal. 101:390-399.

La Scala, N., Lopes, A., Spokas, K.A., Archer, D.W., Reicosky, D.C. 2009. First-Order Decay Models to Describe Soil C-CO2 Loss After Rotary Tillage. Scientia Agricola. 66(5):650-657.

Last Modified: 4/19/2015
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