Soil profile development and recovery on the Southern Great Plains following the US Dust Bowl
1, Jeff Lee2
1The University of Sydney, Sydney, NSW, Australia, 2Texas Tech University, Lubbock, TX, USA
The US Dust Bowl disaster of the 1930s had a profound impact on landscape condition and communities that occupied contiguous parts of Oklahoma, Texas, Colorado, New Mexico and Kansas. Severe wind erosion led to billowing clouds of dust, blowing sand, topsoils stripped away and the formation of miniature sand dunes; a consequence of this erosion was the formation of the Soil Conservation Service (SCS) in 1935. One of the first initiatives of the SCS was to undertake a detailed soil erosion survey of twenty counties at the core of the Dust Bowl region. The survey involved the documentation and mapping of erosion severity, slope, landuse and broad soil type, largely based on textural and structural attributes. This was the first thorough account of soil type distribution for the region, assessed at the height of a period of landscape change. Only in later decades, generally from the 1960s onwards, were these counties mapped in more pedologic and taxonomic detail, with the introduction of local soil series. Since the late 1990s, a number, but not all, of these counties have had update soil surveys carried out by the Natural Resources Conservation Service (NRCS). A conspicuous feature of some of the post-1960s soil surveys is the presence of soil series and soil types that may have been created during the Dust Bowl; an example of this is the Valentine soil series described in Dallam County, Texas, which is a sand dune soil type found commonly in the Nebraska sandhills. It is likely that at least the topsoils of many soil types of the Dust Bowl region were profoundly modified by erosion and/or deposition of sediment during the 1930s, but what is less clear is whether these modified soils have evolved or returned towards their original condition in the more benign 80 years since the end of the Dust Bowl. In this work, we interrogated the 1930s maps created by the SCS to locate areas where the soils were clearly affected by erosion and/or deposition during that decade, and nearby areas where the soils were largely unaffected by these processes. We have matched these locations, and the general 1930s descriptions of the soils at those locations, to the more recent SCS/NRCS soil survey maps to identify the main soil types at these positions, and have then followed up with current-day field description of these soil profiles. While some of the sandier soils appear to have undergone some moderate pedogenesis since the end of the Dust Bowl, the more pronounced soil modification/development has occurred where irrigated cropping has been practiced. Although subtle, the imprint of the Dust Bowl period on the soils of the region is still present.