| 1998 | 1998 | 1998 | 1999 | 1999 | 1999 | 1999 | 2000 | 2000 | 2000 | 2000 | 2001 | |
| Research task | Su | A | W | Sp | Su | A | W | Sp | Su | A | W | Sp |
| Task 1 - Landuse/Recon. | VA | VA | VA/MS | VA/MS | MS/GA | MS/GA | MS/GA | |||||
| Task 2 - Field comparisons | VA | MS | GA | |||||||||
| Task 3 - Microsites | VA | MS | GA | |||||||||
| Task 4 - Modeling | VA | VA/MS | MS | MS/GA | GA |
We have made substantial progress toward meeting the goals set forth in the original research proposal. The project did not commence until summer 1998 and unforseen circumstances delayed field work in Virginia, but the schedule for completion of activities needed only slight modification. In addition to the scheduled tasks, we have nearly completed a manuscript examining the influence of grassland management on C sequestration.
In August 1998, we visited farms in VA to evaluate the potential field sample and microsite locations. We visited five farms and determined that each offered unique characteristics enabling the comparison of intensive grazing management across a range of land resource areas and soil types. Also, two of the farms had a variety of long-term land use histories which enabled the comparison of conversions from native vegetation, long-term cultivation, and long-term hay with intensive and extensive grazing management. Based on our assessment of land use history, soil survey information, and the enthusiasm and future plans of the farmers, we determined that comparative samples and microsites would be established at all five farms.
Though we intended to commence field work in Fall 1998, unusually dry weather led to very dry soil conditions and precluded soil sampling. Samples were collected in March 1999. As noted above, we visited all five farms and collected paired plot samples to examine the potential for C sequestration with improved grazing management. Locations of microsites were established with a differential GPS and a relocatable marker ball was installed at each microsite so that the exact locations of the soil cores can be revisited in the future. Soil cores comprising nearly 1T of soil were returned to NREL and sample preparation and analysis began in mid-March.
Plans are underway to visit Mississippi to review the demonstration farm program and search for farms that will allow comparisons similar to those in Virginia. Working with Walter Jackson, the Mississippi NRCS demonstration farm coordinator, we plan to make a reconnaissance visit April 4-6, 1999 and another visit to collect soil samples and establish microsites in late Spring 1999.
Land use data from a number of different sources were compiled for future modeling use. Sources included both survey (NRI and Agricultural census) and remotely sensed data (GIRAS, AVHRR, and MRLC). A pilot project was begun in VA to evaluate the labor investment required to obtain Agricultural census data from published volumes, as early data is not available electronically. Data from the different sources overlapped significantly, allowing for a comparison between different data sources. All data sets were compared to the NRI data since they are the only data with confidence intervals. Our analyses revealed that the MRLC data is the best data at the county scale, and that GIRAS and MRLC are good sources of data at the MLRA scale. AVHRR data are available at more frequent sampling intervals than the other datasets, but the data do not agree well with the NRI data at either scale. We plan to do similar analyses at the soil map unit scale, and expect to report the results in a peer-reviewed journal article.
Currently we have completed the tasks scheduled for the first year of the project and have implemented plans to begin tasks scheduled for the second year (i.e. MS field visits). Additionally, talks were given at the RLEP annual meeting (November 1998) and at the Center for Analysis of Carbon in Terrestrial Ecosystems (C-ACTE) Orientation Meeting (February 1999). Presentations describing early research results are scheduled for the ‘Agricultural practices and policies for carbon sequestration in soil' meeting (July 1999) and the Ecological Society of America (August 1999). A manuscript describing grassland management and soil C is nearly ready for submission and other manuscripts describing implications of grassland management on global soil C sequestration and inter-comparison of land use datasets are in progress. Also, in cooperation with Glenn Johnson (NRCS, Blacksburg), we developed a proposal to study the influence of intensive grazing management on primary production for three of the farms sampled in Virginia.
Tasks scheduled to be completed during the next funding year are illustrated in Table 1. Tasks include establishment of field sites and sample collection in both MS and GA. A great deal of time will be spent analyzing soils that have been and will be collected. Compilation and comparison of land use data for the entire Southeast region will continue and will be assembled into datasets that will be used to parameterize the CENTURY model. Modeling will commence near the end of the next budget year.