Gully Rehabilitation—A Three‐Stage Process in a Sodic Soil

Abstract

AbstractThe geomorphic, edaphic, and vegetation changes occurring in sodic soils were studied during a gully rehabilitation project in western Colorado. Soil material was collected along transects which traversed individual gullies in the network. A topographic survey was also made of each transect to determine areas of erosion and deposition. Along each transect samples were collected on exposed sodium banks, recent and old gully bank colluvium, sediment deposited in the channel, partially stable gully banks, and stable gully banks. The six sample locations were sampled in 1962, 1965, 1967, and 1981. The samples collected at the six locations were analyzed for pH; soluble calcium, magnesium, and sodium in a saturated extract; total calcium, magnesium, and sodium; water soluble sodium; cation exchange capacity; and soil texture. Exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR) were calculated. The analysis of the data showed that gully rehabilitation occurred in three stages: nonvegetated sodium banks disintegrated; the colluvial material from these eroded banks was weathered and leached; and, finally when enough sodium had been leached from the eroded material, it was stabilized and vegetated as older colluvial material at the base of high sodium gully banks or as channel alluvium deposited behind gully structures. These changes led to an overall stabilization of the gullies and reduced suspended sediment and peak flows.