Soil Hydrology of Texas Vertisols and Claypans.

The soils of Central Texas offer many challenging and interesting projects to a hydropedologist. Because hydropedology uses soil morphology to better quantify and model water movement in the soil, it is easy to see how working in the state with highest acreage of Vertisols and vertic integrates can provide many opportunities for research challenges. However, overlooking Alfisols with abrupt transitions from fine sand in the surface to sandy clay subsoil, as well as very strong prismatic structure, would be a mistake. Soil of Central Texas provide a wide range of hydrology questions because of the spatial variability present. The Gulf of Mexico has had a very striking influence on Texas soils as well as the climate. The influence of the Gulf is easy to imagine with a full range of parent materials that represent all textural classes. Central Texas covers the Udic to Ustic soil moisture regimes as well as any imaginable transition therein—the weather is so temporally variable its difficult to put a fine point on any moisture regime in a specific location. In addition to the variability in rainfall this Udic/Ustic transition creates interesting hydrology as affected by boundary transitions between horizons. Over the past 13 years the Texas A&M University pedology program has evaluated the effect of Vertisol microtopography on multiple elements of the water cycle. This presentation will cover temporal and spatial cracking dynamics, giglai, and interesting Vertisol observations. The effect of clay pan soils in modeling boundary layers in land surface modeling will also be presented. Soil surface morphology, particularly soil structure, will be discussed with respect to the importance of managing soils to capture rainfall. The context of this discussion is across soils of Central Texas, so be prepared for Texas hyperbole and Lone Star soil facts.