ARM/GCIP NESOB-96 ARM Soil Texture Data Set 1.0 General Description The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Soil Texture Data Set is one of the various sub-surface data sets developed for the ARM/GCIP (Global Energy and Water Cycle Experiment [GEWEX] Continental-scale International Project) 1996 Near-Surface Observation (NESOB-96) Data Set. This data set contains a summary table of the percentages of sand, silt, and clay fractions in each soil layer at each of the ARM SWATS (Soil Water and Temperature System) sites at the SGP site. Also included is the corresponding USDA texture class as determined from the "soil triangle". The soil characterizations were performed by Oklahoma State University. No additional qulaity control was performed by the University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS). 2.0 JOSS Processing These data arrived at JOSS on a CD-ROM in Excel spreadsheet format. JOSS converted the data into a columnar ASCII format. 3.0 Contact Ron Elliot 111 Agricultural Hall Oklahoma State University Stillwater, OK 74078 Telephone: 405-744-8423 Fax: 405-744-6059 Email: relliot@okstate.edu 4.0 Sites Site Facility Elevation Latitude Longitude Surface (m) Type ------------------------------------------------------------------------ Ashton, KS EF-9 386 37.133 N 97.266 W Pasture Byron, OK EF-11 360 36.881 N 98.285 W Alfalfa Coldwater, KS EF-8 664 37.333 N 99.309 W Rangeland Cordell, OK EF-22 465 35.354 N 98.977 W Rangeland Cyril, OK EF-24 409 34.883 N 98.205 W Wheat Elk Falls, KS EF-7 283 37.383 N 96.180 W Pasture El Reno, OK EF-19 unknown 35.557 N 98.017 W Pasture Halstead, KS EF-5 440 38.114 N 97.513 W Wheat Hillsboro, KS EF-2 450 38.306 N 97.301 W Pasture Lamont, OK EF-13&14 318 36.605 N 97.485 W Pasture Larned, KS EF-1 632 38.202 N 99.316 W Wheat LeRoy, KS EF-3 338 38.201 N 95.597 W Wheat Meeker, OK EF-20 309 35.564 N 96.988 W Pasture Morris, OK EF-18 217 35.687 N 97.856 W Pasture Pawhuska, OK EF-12 331 36.841 N 96.427 W Native Plevna, KS EF-4 513 37.953 N 98.329 W Rangeland Ringwood, OK EF-15 418 36.431 N 98.284 W Pasture Seminole, OK EF-25 277 35.245 N 96.736 W Pasture Towanda, KS EF-6 409 37.842 N 97.020 W Alfalfa Tyro, KS EF-10 248 37.068 N 95.788 W Wheat Vici, OK EF-16 602 36.061 N 99.134 W Wheat Lamont is also the CF (Central Facility). EF is Extended Facility. 5.0 Note on Remainder of Document The remainder of this document is taken from Elliot and Brown (1998). 6.0 INTRODUCTION In 1995, the University of Oklahoma's Cooperative Institute for Mesoscale Meteorological Studies was awarded a research grant by the Climate and Global Change Program of the NOAA Office of Global Programs. The project was entitled "Meeting GEWEX/GCIP Measurement Needs by Adding Automated Measurement of Soil Moisture and Temperature Profiles to the DOE ARM/CART Southern Great Plains Site" (Schneider and Fisher, 1997). The co-principal investigators, Dr. Jeanne M. Schneider and Dr. Peter J. Lamb, subcontracted a portion of the work to Oklahoma State University. Specifically, the subcontractor was responsible for characterizing the soils and performing independent soil-moisture measurements at each of 21 facilities (field research sites) in the ARM/CART study area in Oklahoma and Kansas. This report presents the results of those investigations, and discusses the field and laboratory procedures that were used to acquire the data. 7.0 FIELD SAMPLING The locations of the ARM/CART Central Facility and Extended Facilities were determined from maps provided by Site Operations. Site visits and digging operations were coordinated through Site Operations. In order to minimize site disturbance and safety risks, soil sampling was performed using hand tools. All samples were collected by Mr. Brandon Claborn, OSU Biosystems and Agricultural Engineering student, usually with the assistance of Dr. Jeanne Schneider, project co-PI. After arrival at each facility, the specific location of the 6' x 6' SWATS plot was determined. [SWATS is the acronym for "Soil Water and Temperature System", and refers to the sensors installed as part of the OGP-sponsored project.] The surface features in the immediate vicinity of the SWATS plot were visually assessed in order to determine the most representative areas for soil sampling. Unless otherwise directed by Site Operations, all digging occurred just outside the electric fence enclosing the Energy Balance Bowen Ratio (EBBR) system (usually 5 m directly west of the EBBR's exchange mechanisms). Power to the electric fence was disconnected for the duration of the visit. A preliminary look at the different soil horizons and their respective depths was needed before any sampling could be done. This was accomplished by digging a sample pit. The pit was adjacent to the SWATS plot and just outside the fence of the EBBR. The soil inside the SWATS plot remained undisturbed. The sample pit was dug using a sharpshooter shovel. The pit had dimensions of approximately 70 cm x 15 cm x 60 cm (L x W x D), with the extracted soil loaded into buckets to facilitate refilling. This pit exposed the soil profile and soil horizons to visual inspection; descriptions of the soil layers (2 to 4 in number), and their respective depths were recorded. The soil color of each layer was determined by using the Munsell Soil Color Chart. The texture-by-feel method was used to determine the soil textures qualitatively. The soil was replaced in the observation pit in the reverse order that it was taken out, and original sod was replaced in all areas so the site was returned as close to its original state as possible. Undisturbed core samples were collected for laboratory determination of soil-water-retention characteristics and bulk density. These samples were taken using a model number 0200 soil core sampler from Soilmoisture Equipment Corporation (see "Piston Samplers" in ASTM D 4700 - 91). Core samples were taken from each soil horizon at each of two different locations near the sample pit. To obtain samples from depths other than at the surface, a hole was dug using a post hole digger to reach the desired depth for sampling without compacting the soil. The soil sampler holds three numbered rings each with a height of 3 cm and an outside diameter of 5.72 cm (2.25 in). The sampler has a wedge cutting tip to help provide undisturbed samples. The sampler was driven into the ground by using the driving hammer. The rings were removed and then the sample was cut transversely to separate the rings. The rings were sealed with plastic caps and placed in numbered containers for transport to the laboratory at Oklahoma State University. The sampling depths, ring numbers, and container numbers were recorded on the data sheet. Some bag samples of soil were also collected for particle-size and organic-carbon analyses. The bag labels were recorded on the data sheets. The sampling holes were returned as close to the original state as possible. The locations of the test pits, sample locations, and any other disturbed areas were recorded on the data sheet. Other special characteristics of the site, including ground cover, were also recorded. Two additional visits were made to each site in order to obtain samples for direct measurement of soil water. These were to provide independent data for validation of the SWATS measurements of soil water content at the top 4 depths (5, 15, 25, and 35 cm). Ideally, the two visits to a given site were made at times of contrasting soil moisture conditions, but this was not always possible. The same digging and coring procedures as described above were used for the soil moisture sampling, except that a ring with a height of 6 cm was used in place of two 3-cm rings. The 6-cm tall sample was centered on the depth of interest. Triplicate samples were obtained (4 depths in each of 3 holes, for a total of 12 ring samples). The samples were placed in numbered cans and transported to the laboratory in an insulated chest. 8.0 LABORATORY PROCEDURES Particle size distributions were analyzed in the laboratory of Dr. Glenn O. Brown, Associate Professor in the Biosystems and Agricultural Engineering Department at Oklahoma State University. Samples were prepared according to ASTM D 421 - 85 (1985). Hydrometer and wet sieving procedures were used (ASTM D 422 - 63, 1963; ASTM D 1140 - 92, 1992). The laboratory data were entered into a spreadsheet, and the resulting particle size distributions were plotted. Percentages of sand, silt, and clay were calculated, and used to assign the soil textural class according to the USDA classification system (i.e., the "soil triangle"). 9.0 Data Set Contents This is a summary table of the percentages of sand, silt, and clay fractions in each soil layer at each site. Also listed is the corresponding USDA texture class as determined from the "soil triangle". 10.0 ACKNOWLEDGMENTS Appreciation is extended to Dr. Nick Basta for his willingness to run the organic carbon tests. This project would not have been possible without the dedicated efforts of many students and staff in the OSU Biosystems and Agricultural Engineering Department: Brandon Claborn Tom Underwood John Roll Shellie Miller Diana Loudenslager Jason Vogel Hope Nickels Ken Fisher 11.0 REFERENCES American Society for Testing and Materials. 1963. Standard Test Method for Particle-Size Analysis of Soils. D 422 - 63, Philadelphia, Pennsylvania. American Society for Testing and Materials. 1968. Standard Test Method for Capillary-Moisture Relationships for Coarse- and Medium-Textured Soils by Porous-Plate Apparatus. D 2325 - 68, Philadelphia, Pennsylvania. American Society for Testing and Materials. 1985. Standard Practice for Dry Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants. D 421 - 85, Philadelphia, Pennsylvania. American Society for Testing and Materials. 1991. Standard Guide for Soil Sampling from the Vadose Zone. D 4700 û 91, Philadelphia, Pennsylvania. American Society for Testing and Materials. 1992. Standard Test Method for Amount of Material in Soils Finer Than the No. 200 (75 um Sieve). D 1140 - 92, Philadelphia, Pennsylvania. Elliot, R. L. and G. O. Brown, 1998: Final Project Report for Subcontract No. 1995-27: Meeting GEWEX/GCIP Measurement Needs by Adding Automated Measurement of Soil Moisture and Temperature Profiles to the DOE ARM/CART Southern Great Plains Site. Oklahoma State University, Stillwater, Oklahoma. Klute, A. 1986. Water Retention: Laboratory Methods. Chapter 26 in the Second Edition of Methods of Soil Analysis, Part 1, Physical and Mineralogical Methods, Agronomy Monograph No. 9, American Society of Agronomy - Soil Science Society of America, Madison, Wisconsin. Nelson, D. W. and L. E. Sommers. 1996. Total Carbon, Organic Carbon, and Organic Matter. Chapter 34 in Methods of Soil Analysis, Part 3, Chemical Methods, SSSA Book Series No. 5, Soil Science Society of America - American Society of Agronomy, Madison, Wisconsin. Schneider, J. M. and D. K. Fisher. 1997. Meeting GEWEX/GCIP Measurement Needs by Adding Automated Measurement of Soil Moisture and Temperature Profiles to the DOE ARM/CART Southern Great Plains Site. Preprints, 13th Conference on Hydrology, American Meteorological Society, Long Beach, California, February. van Genuchten, M. T., F. J. Leijand and S. R. Yates. 1991. The RETC Code for Quantifying the Hydraulic Functions of Unsaturated Soils. EPA/600/2-91/0655, U.S. Environmental Protection Agency, Robert S. Kerr Environmental Research Laboratory, Ada, Oklahoma. 85 pp.