Wednesday, November 15, 2006 - 8:45 AM

Mapping, Laboratory Analyses and Classification of Gypsiferous Soils.

Wayne Hudnall1, Lynn Loomis2, Charles T. Hallmark3, B.L. Allen1, Susan Casby-Horton2, and Arlene Tugel4. (1) Texas Tech Univ, Plant & Soil Science Dept, Lubbock, TX 79409, (2) USDA-NRCS, P O Box 362, Marfa, TX 79843, (3) Texas A&M Univ, Dept of Soil & Crop Sciences, MS2474, College Station, TX 77843-2474, (4) New Mexico State Univ, NRCS, Jornada Exp Range, Box 30003, 3JR, Las Cruces, NM 88003-0003

Gypsiferous soils are usually rangeland and are used for military operations, oil and gas extraction, wildlife habitat, and livestock grazing. Resource management concerns include loss of topsoil, physicochemical crusting, dust from roads, and minimally re-vegetated pipelines. Unique plant communities occur on these soils and their ability to recover after changes in dynamic soil properties is unknown. The parent materials of many of these soils contain 90-100% gypsum, making them unique. There are an estimated 450,000 acres of soils formed in Permian age gypsum bedrock of the Gypsum Plains of TX and NM and 850,000 acres formed in reworked gypsum evaporites of Pleistocene and Holocene lake basins, dunes and fan piedmonts of the Tularosa and Salt Basins in NM and TX. Soils formed in gypsum bedrock and gypsum evaporites may be as different from most mineral soils as are Histosols and Andisols. The most basic and probably useful of all soil properties, particle size, cannot be measured with current methods without removing almost all of the soil itself. This is only one example of the challenges facing the mapping crews. Many questions have been formulated as to field description nomencalature, taxonomy and interpretations based upon field and laboratory data.  An overview of the problems and possible soulutions will be presented.