More Like this

1. Erodibility of Claypan Soils in Southeastern Kansas

   Mathis, Mark ; Kulesza, Stacey ; Sassenrath, Gretchen ( November 2017 , Kansas Governor's Water Conference)

   The objective of this research is to determine the fundamental mechanisms that cause loss of topsoil. Claypan soils cover approximately 10 million acres in the United States and are characterized by a highly impermeable layer below the topsoil. This impermeable layer acts as a barrier for infiltrating water which may be increasing the erosion rate and sediment transport of upper soil layers. This increasing topsoil depletion ultimately limits the productive capacity of agronomic fields. This study focuses on the undermining of the topsoil due to the impermeable claypan layer in Southeastern Kansas where the topsoil depth is limited and, in places, the claypan layer is exposed at the surface. Using LiDAR-derived digital elevation maps, the potential areas of critical soil loss and hydrologic flow patterns is determined. Surface soil apparent electrical conductivity (EC) measurements highlight the soil variability throughout the field. Electrical Resistivity Tomography (ERT) surveys is also performed to determine the depth to the claypan layer in low and high crop yield areas. The results indicate that the areas of high EC correlated with high clay content and low crop yield, while areas of low EC correlated with high crop yield. The results also indicate that the claypan layer in the low crop yield area is 1.0 m thick and significantly thins once reaching the high crop yield area. The next phase of this ongoing research is to measure the soil properties between the low and high crop yield areas, measure the movement of water at the claypan interface, and measure sediment transport at the claypan interface. 

   more » « less
2. Electrical Resistivity Tomography of Claypan Soils in Southeastern Kansas

   https://doi.org/https://doi.org/10.4148/ 2378-5977.7574  

   Mathis, M. A. ; Tucker-Kulesza, S. E. ; and Sassenrath, G. F. ( March 2018 , Kansas Agricultural Experiment Station Research Reports)

   Claypan soils cover approximately 10 million acres across several states in the central United States. The soils are characterized by a highly impermeable clay layer within the profile that impedes water flow and root growth. While some claypan soils can be productive, they must be carefully managed to avoid reductions to crop productivity due to root restrictions, water, and nutrient limitations. Clay soils are usually resistant to erosion but may exacerbate erosion of the silt-loam topsoil. Soil production potential is the capacity of soil to produce at a given level (yield per acre). The productive capacity is tied to soil characteristics, which can be highly variable within a field. In this project, we have used imagery analysis to study the aerial images and terrain of fields during different productive times of the year to identify where soil samples should be collected for more discrete analysis. Soil samples provide valuable information; however, the amount of data obtained from a relatively small area within a field does not provide sufficient information to delineate the subsurface characteristics. To address the limitations of sampling, we have also employed the use of yield maps collected from commercial yield monitors on production-scale combines and surface electrical conductivity measurements (Sassenrath and Kulesza, 2017). Soil conductivity is a measurement of how well a representative volume of soil conducts electricity. Soil conductivity is a function of the soil clay content, moisture content, and other measurable soil properties (Kitchen et al., 2003); as such, it has become a valuable tool for mapping in-field variability. The main advantage of a soil conductivity measurement is that the entire surface of a field can be imaged. The disadvantage of a soil conductivity measurement is that data are only collected near the surface (10 – 30 inches) and the measurements are relative measurements. This means that the conductivity mappers can identify changes in soil properties, but they cannot directly tell researchers what caused these changes. Electrical resistivity tomography (ERT) is a popular near-surface geophysical measurement for geophysical and engineering applications. The term “near-surface” generally means down to around 30 feet in the subsurface. Electrical resistivity is the reciprocal measurement of electrical conductivity; therefore, both systems measure differences in the same soil properties. ERT measurements are different than surface electrical conductivity measurements because ERT collects a “slice” of data into the subsurface, as opposed to only changes at the surface area. Relative measurements, similar to those collected in an electrical conductivity survey, are collected; however, in ERT studies the data are mathematically inverted to yield the true electrical resistivity of the soil with depth. This allows an interpretation of the changing soil properties with depth to reduce the required amount of sampling. A disadvantage of an ERT survey is that the data acquisition is stationary so mapping an entire field is not feasible. We have used a coupled process of imagery and terrain analysis, yield maps, and electrical conductivity measurements to guide the locations of ERT surveys in this project (Tucker-Kulesza et al. 2017). 

   more » « less
3. Hydro‐geomorphic behavior of contrasting tropical landscapes and critical zone response to changing climate

   https://doi.org/10.1002/esp.4503  

   Dialynas, Yannis G. ; Bras, Rafael L. ( October 2018 , Earth Surface Processes and Landforms)

   The potentially important influence of climate change on landscape evolution and on critical zone processes is not sufficiently understood. The relative contribution of hydro‐climatic factors on hillslope erosion rates may significantly vary with topography at the watershed scale. The objective of this study is to quantify the hydro‐geomorphic behavior of two contrasting landscapes in response to different climate change scenarios in the Luquillo Critical Zone Observatory, a site of particular geomorphological interest, in terms of hillslope erosion and rainfall‐triggered landslides. We investigate the extent to which hillslope erosion and landslide occurrence remain relatively invariant with future hydro‐climatic perturbations. The adjacent Mameyes and Icacos watersheds are studied, which are underlain by contrasting lithologies. A high resolution coupled hydro‐geomorphic model based on tRIBS (Triangulated Irregular Network‐based Real‐time Integrated Basin Simulator) is used. Observations of landslide activity and hillslope erosion are used to evaluate the model performance. The process‐based model quantifies feedbacks among different hydrologic processes, landslide occurrence, and topsoil erosion and deposition. Simulations suggest that the propensity for landslide occurrence in the Luquillo Mountains is controlled by tropical storms, subsurface water flow, and by non‐climatic factors, and is expected to remain significant through 2099. The Icacos watershed, which is underlain by quartz diorite, is dominated by relatively large landslides. The relative frequency of smaller landslides is higher at the Mameyes watershed, which is underlain by volcaniclastic rock. While projections of precipitation decrease at the study site may lead to moderate decline in hillslope erosion rates, the simulated erosional potential of the two diverse landscapes likely remains significant. © 2018 John Wiley & Sons, Ltd.

    

   more » « less
4. Applicability and Sensitivity of Field Hydrology Modeling by the Soil Plant Air Water (SPAW) Model Under Changes in Soil Properties

   https://doi.org/10.13031/ja.15306  

   Saha, Ajoy Kumar ; McMaine, John ( January 2023 , Journal of the ASABE)

   Highlights Changes to soil properties and precipitation scenarios significantly affect the water balance in agro-hydrology. SPAW model is sensitive to simulated runoff and infiltration, but it has limitations in responding to soil compaction and organic matter change. Increasing organic matter (1% to 5%) did not significantly affect runoff or infiltration in silty and sandy loam soil. Low precipitation generates significantly lower runoff (%) and higher infiltration. Abstract. Agricultural practices can change soil properties and the amount of runoff generated from a landscape. Modeling results could be significantly different than expected if the web soil survey or other commonly used remote sensing applications are used as model inputs without site verification. This study assessed the applicability and sensitivity of the Soil-Plant-Air-Water (SPAW) Model for simulating the runoff (%) and infiltration (%) components of the water balance for various soil physical properties, cover crop, and weather variables. Soil profiles in 135 combinations were developed with three soil classes (sandy loam, silt loam, and clay), five organic matter levels (1%, 2%, 3%, 4%, and 5%), three levels of compaction (low, medium, and high), and three topsoil layer thicknesses (7.6 cm, 11.4 cm, and 15 cm). Also, three cover crop treatments were simulated by modifying surface cover and evapotranspiration during the non-growing season. Finally, two precipitation regimes were considered (Iowa City, IA, as high precipitation and Brookings, SD, as low precipitation) to simulate runoff and infiltration. In total, 810 scenarios were run, resulting in over 300 million data points. This study confirmed that soil texture, bulk density, and topsoil thickness significantly (p<0.01) influence runoff generation and infiltration percentage based on the water balance criterion. Interestingly, the SPAW model had no significant response on runoff (%) and infiltration (%) to organic matter levels changing from 1% to 5%. This simulation demonstrates that runoff estimations can be significantly influenced by soil properties that can change due to agricultural conservation practices (ACPs) or, conversely, by compaction events. Inputs to models must account for these changes rather than relying only on historical or remote sensing inputs. Keywords: Agricultural conservation practices, Conservation agriculture, Field hydrology, Infiltration, Runoff, SPAW. 

   more » « less
5. Germination and early establishment of dryland grasses and shrubs on intact and wind-eroded soils under greenhouse conditions

   https://doi.org/10.1007/s11104-021-05005-9  

   Niu, Furong ; Pierce, Nathan A. ; Archer, Steven R. ; Okin, Gregory S. ( May 2021 , Plant and Soil)

   Grassland-to-shrubland transition is a common form of land degradation in drylands worldwide. It is often attributed to changes in disturbance regimes, particularly overgrazing. A myriad of direct and indirect effects (e.g., accelerated soil erosion) of grazing may favor shrubs over grasses, but their relative importance is unclear. We tested the hypothesis that topsoil “winnowing” by wind erosion would differentially affect grass and shrub seedling establishment to promote shrub recruitment over that of grass.

   We monitored germination and seedling growth of contrasting perennial grass (Bouteloua eriopoda,Sporobolus airoides, andAristida purpurea) and shrub (Prosopis glandulosa,Atriplex canescens, andLarrea tridentata) functional groups on field-collected non-winnowed and winnowed soils under well-watered greenhouse conditions.

   Non-winnowed soils were finer-textured and had higher nutrient contents than winnowed soils, but based on desorption curves, winnowed soils had more plant-available moisture. Contrary to expectations, seed germination and seedling growth on winnowed and non-winnowed soils were comparable within a given species. The N₂-fixing deciduous shrubP. glandulosawas first to emerge and complete germination, and had the greatest biomass accumulation of all species.

   Germination and early seedling growth of grasses and shrubs on winnowed soils were not adversely nor differentially affected comparing with that observed on non-winnowed soils under well-watered greenhouse conditions. Early germination and rapid growth may giveP. glandulosaa competitive advantage over grasses and other shrub species at the establishment stage in grazed grasslands. Field establishment experiments are needed to confirm our findings in these controlled environment trials.

    

   more » « less