Cropping management system influences on playa sediments in US southern high plains

摘要

Playa wetlands are unique, depressional geomorphic features on the Southern High Plains of the United States. These playas function as runoff catchment basins and bio-diverse wildlife habitat areas. The more than 20,000 playa wetlands in the SouthernHigh Plains are thought to serve as major Ogallala aquifer recharge sites. Playa wetland sediment deposits are thought to impede aquifer recharge and increase evaporative water loss. This study evaluated cropping management system effects on sediment accumulation in six playa wetlands (3 cultivated, 3 rangeland). Soil cores were collected using a hydraulic probe to a depth of 1.5 m at twenty-five locations in each of the playas. Particle-size distribution and soil color proved to be adequate parametersto identify recent sediment added to the playas. Particle size distribution, however, was more useful as an interpretation and analysis tool than for distinguishing sediments. Sediment added to cropped playas was indicated by a very dark grayish brown (10YR 3/2) to very dark gray (10YR 3/1) soil-color transition. Sediment depth and land-use were directly related with greater sediment accumulation in cropped playas than in rangeland playas. Three-dimensional models will be used to depict the original playa basin with and without sediment additions.