Shrink-Swell Dynamics of Vertisol Catenae under Different Land Uses
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Because of the dynamic nature of shrinking and swelling of soils that are classified as Vertisols, partitioning of rainfall into infiltration and runoff in a Vertic watershed is more temporally and spatially unique than in most other watersheds. Hydrology models that account for realistic representation of crack dynamics are rarely used because the spatial and temporal patterns of cracking across a catena and under different land uses are poorly understood. The objectives of the study were to 1) determine if variability in soil cracking on a Vertisol catena, having the same soil and land cover, could be explained by shrink-swell potential of the soil and changes in soil water content; 2) characterize the temporal and spatial variability of the shrinkage of a Vertisol under different land uses; and 3) determine the relationship between specific volume and water content of soils, particularly between saturation and field capacity. The research was conducted in Vertisol catenae of the Houston Black and Heiden soil series. The catenae were located within the USDA-ARS Grassland, Soil and Water Research Laboratory, Riesel Texas. Soil samples were taken to characterize the general properties of the soils. In situ bi-weekly measurements of vertical soil movements and soil water contents were made over a two-year span. Because shrink-swell potential was high at most landscape positions, soil water content was the primary factor driving the spatial and temporal variability of soil shrinking and swelling. The measured relationship between the amount of soil subsidence and water loss generally agreed with what would be theoretically expected. Maximum soil subsidence was 120 mm in the grazed pasture, 75 mm in the native prairie, and 76 mm in the row cropped field. Shrinkage of the whole soil was not equidimensional, and the study generally indicates more horizontal shrinkage than vertical shrinkage. Laboratory analysis showed an appreciable change in volume of soils between saturation and field capacity, suggests a layer of soil layer can subside up to 4% while drying from saturation to field capacity, which indicates the common laboratory measure of shrink swell potential does not capture the complete shrink-swell behavior of soils.
Dinka, Takele Mitiku (2011). Shrink-Swell Dynamics of Vertisol Catenae under Different Land Uses. Doctoral dissertation, Texas A&M University. Available electronically from