Soil Surface Bulk Density Sampling Results
 Soil sampling during SGP97 |
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The Data
The results obtained from sampling the soil surface layer (0-5 cm) bulk density are provided. For interpretation of codes used for areas and sites please refer to the experiment plan. Field notebooks are available for use at the USDA Hydrology Lab, they will not be loaned out. Also included in this information file is the background material from the sampling plan describing the design and protocols used.The Files
Two levels of data files will be available, the summary (means and standard deviations of all sites) and the raw data. Files are all ASCII text. The data contained in these files is as followsFormats
Raw Data Format ASCII text table Column Headings Area ID Site ID Date (Month-Day) Start Volume (ml) End Volume (ml) Total Volume (ml) Wet Weight (g) Dry Weight (g) Bulk Density (g/cm3) Gravimetric Soil Moisture Vegetation Note (if any)
Summary Format ASCII text table Column Headings Area ID Site ID Date (Month-Day-Year) Vegetation Note Mean Bulk Density (g/cm3) Standard Deviation of Bulk Density (g/cm3) Note (if any) Name and Directory Information
File Naming Convention
- Raw Data File (LIMITED DISTRIBUTION) sgp97bdr.txt
- Summary File bdsum.tx
The Science
Sampling Plan Bulk density is used to convert the gravimetric samples to volumetric soil moisture. A volume extraction technique was used. In general, four samples per site were taken.
Sampling Protocol Only a brief summary is provided. Please see the experiment plan for details. After selecting a location, vegetation is removed. A volume of surface soil is extracted to a specific depth (5 cm). Using the volume extracted and the dry weight of the soil extracted, the bulk density is computed. The computation is as follows
Note that the data presented in the tables have had the tare weights removed. It is also possible to compute the soil moisture of the sample used for the bulk density
- Compute volume of soil extracted: Volume Total = Volume End - Volume Start
- Compute dry soil mass extracted: sample dry weight - tare
- Compute bulk density: dry soil mass extracted / soil volume extracted
Gravimetric soil moisture= 3D(wet weight - dry weight) / dry weight
Data Access and Contacts
FTP SiteThe Soil Bulk Density Summary File from SGP97 is in the following GES DISC ftp site:
Summary file (ASCII)
The soil bulk density raw data files from SGP97 are for limited distribution only. To obtain them, contact Principal Investigator Thomas Jackson at the Agricultural Research Service Hydrology Lab (see "Points of Contact below.")
Points of Contact
The Principal Investigator for the SGP97 Gravimetric Soil Moisture data is
Thomas J. Jackson
USDA ARS Hydrology Lab
Bldg. 007, Rm. 104, BARC-West
Beltsville, MD 20705
tjackson@hydrolab.arsusda.gov
Voice: 301-504-8511
For more information using SGP97 GES DISC data, contact:
Hydrology Data Support Team
Goddard Earth Sciences Data and Information Services Center (GES DISC)
Code 610.2
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771
hydrology-disc@listserv.gsfc.nasa.gov
Voice: 301-614-5165
Fax: 301-614-5268
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Last update:Thu Jan 28 09:34:12 EST 1999 Page Info: Hydrology Data Support Team -- hydrology-disc@listserv.gsfc.nasa.gov Web Curator: Anthony Drake NASA official: Steve Kempler, DAAC Manager -- Steven.J.Kempler@nasa.gov |