Dispersive Erosion and Entisol‐Panspot Genesis in Sodium‐Affected Landscapes

Abstract

In Natriboroll complexes, commonly barren, eroded Entisol or remnant Natriboroll areas occur that are devoid of vegetation. This study investigates the genesis, stratigraphy, and characteristics of panspots. The study consists of a detailed grid sampling of 121 pedons in a 20 by 20 m area of panspots (Entisol), revegetated panspots (Entisol), and Glossic and Leptic Natriborolls. Topographic and soil morphological parameters were compared with electrical conductivity, soluble Ca, Mg, HCO3, Cl, SO4, exchangable H, sodium adsorption ratio (SAR), particle size, and water‐dispersible clay. Field evidence clearly showed dispersion‐induced erosion resulting from a documented rainstorm. Water‐dispersible clay supported these observations. Morphologic indicators of leaching intensity and results from a salinity survey showed soil properties consistently related to surface vegetation density. In barren panspots, no development was evident but, in revegetated panspots, a leaching regime was evident and modest structural development could be seen. Chemical and morphological data suggested two water‐movement regimes in panspot development. A diagrammatic model illustrates the role of throughflow and discharge of saline‐sodic water and mechanical/dispersive erosion in panspot genesis. Revegetated panspot zones result from a renewal of soil development that slowly reverses the effects of dispersive erosion. Lateral water flow in anisotropic, sodic parent materials is a major factor in the development of panspots.

Factors Controlling Distribution of Selenium by Geomorphic and Pedologic Processes in a Semi-Arid Environment, Laramie Basin, Wyoming

“…Gypsum accumulation was at great depth (159cm) in this soil. This pedon and pedons C, E, F and G represent a balance between the accumulation of materials from upslope and surface erosion in the form of miniature scarps (dispersive erosion, Hopkins et al, 1991). The rate of this erosion has been slow enough that the distribution of organic matter is "normal" in all pedons of the transect.…”

Cropping pattern changes diminish agroecosystem services in North and South Dakota, USA

“…In perennially covered systems, these dissolved salts are not typically found at the surface because the vegetation takes up water throughout the season (Black, Brown, Halvorson, & Siddoway, ). However, these salts can accumulate in bare areas (Hopkins, Sweeney, & Richardson, ), such as those tilled and cleared for crop production, making vegetation reestablishment difficult.…”

Influences of soil amendments on alfalfa production and soil properties

“…Soluble amendments rely on downward water movement to reach the natric horizon, which is a challenge under dryland conditions in semi‐arid regions like the NGP where potential evapotranspiration (PET) may be twice as high as annual precipitation (NDAWN, 2019). Further, the challenge of facilitating movement of ions to the appropriate depth is exacerbated by variability in depth of natric horizons in the NGP, which can occur at depths of less 4 in to greater than 16 in, even within small areas (<1,100 ft 2 ; He et al., 2018; Hopkins, Sweeney, & Richardson, 1991). Additionally, even successful application of these amendments in one season may be counterbalanced by the continual deposition of Na + ions from groundwater; thus, many land managers may install subsurface tile drainage to discharge groundwater before it reaches the rooting zone (Carter, Bengtson, & Rogers, 1988).…”