HR: 1340h
AN: B53B-1190    [Abstracts]
TI: Modeling of Local and Regional Soil Carbon Balance under Various Agricultural Managements
AU: Wimberley, J
EM: wimberjc@eas.slu.edu
AF: Dept of Earth and Atmospheric Sci, St. Louis University, 3642 Lindell Blvd, St. Louis, MO 63018, United States
AU: * Pan, Z
EM: panz@eas.slu.edu
AF: Dept of Earth and Atmospheric Sci, St. Louis University, 3642 Lindell Blvd, St. Louis, MO 63018, United States
AU: Segal, M
EM: segal@iastate.edu
AF: Dept of Agronomy, Iowa State University, Iowa State Univeristy, Ames, IA 50010, United States
AU: Takle, E
AF: Dept of Agronomy, Iowa State University, Iowa State Univeristy, Ames, IA 50010, United States
AU: Shi, Q
EM: QSHI@eas.slu.edu
AF: Xinjiang University, Xinjiang University, Urumqi, XJ 100000, China
AB: We employed the Daily CENTURY (DayCent) soil organic matter model in a number of sensitivity simulations, in an attempt to quantify the effects of various factors on soil carbon (SC) levels. The site chosen for the simulations was Ames, Iowa, USA (42.03°N, 93.63°W), between 1894 and 2005. A control simulation was carried out using realistic assumptions of farming practices (tillage type, rotation pattern, fertilization, cultivar choice) and actual observed weather data (temperature and precipitation). The observed increase in atmospheric CO2 concentration during this time period was accounted for in the simulations. The sensitivity simulations varied one aspect of the simulation for the entire period. When compared against the control run, the sensitivity runs quantify the response of the modeled ecosystem to changes in the various aspects. Results illustrated that SC levels are generally higher without the use of tillage, or when the soil is disturbed only minimally. Application of nitrogen fertilizer to corn was found to maintain a higher SC level than unfertilized corn. A prescribed cooled climate run, as well as a dry run, produced higher SC levels than the control. We expanded the study above while attempts were made to simulate ecosystem dynamics over parts of the Midwestern United States. A large number of sites in two meteorological networks - the Automated Surface Observing System (ASOS) and the National Weather Service Cooperative Observer Program (Co-Op) - were chosen from the available stations in Illinois, Iowa and Missouri. Soil profile and land-use characteristics for each station were determined from gridded terrain data used in a mesoscale meteorological model; using these in conjunction with the weather observations, DayCent was run at each site, and total seasonal net primary production (NPP) was spatially interpolated over the region. For each of the years 2000 through 2006, the simulated NPP fields were compared against satellite observations of total annual NPP reported by the NASA- TERRA program, thus providing some validation tests for the model performance. Initial results suggest that refinements are needed in the application of the two-dimensional DayCent system. Accounting for such refinements, results of NPP and SC sensitivity to the previous aspects, over entire Midwest region, will be presented.
DE: 0402 Agricultural systems
DE: 0429 Climate dynamics (1620)
DE: 0476 Plant ecology (1851)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting