Trends in soil chemistry and O-horizon depths across an urbanization gradient


Madeline Gay

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Publication Date

Spring 2021


Urbanization impacts soil quality due to elevated pollutants and fertilizers levels, soil compaction, and reduced water infiltration, which results in altered soil chemical properties and a reduction in habitat quality for plants and wildlife. We hypothesized that soils within the most urbanized locations were more likely to exhibit elevated pH levels, soil nutrients, and have less organic material (O-horizon) than more rural soils. This study examined soil quality in three locations along Pittsburg’s urbanization gradient: Pittsburg State University (Urban), Wilderness Park (Urban-Rural boundary), and the Rob Prairie (Rural). We quantified urbanization by calculating the percent impervious cover within a 500 m buffer of the sampling area with ArcGIS. We confirmed our hypothesized urbanization rankings for each site, as the three sampling locations were surrounded by 93.4%, 39.4%, and 27.7% impervious cover, respectively. We collected three soil samples from each site in February 2021. We measured the depth of the O-horizon with a soil corer, and tested soil chemistry with LaMotte soil kits. Specifically, we tested for soil pH and the concentration of soil nutrients: Phosphorous (P), Nitrogen (N), and Potassium (K). Our soil core samples showed that Pittsburg State University has less O-horizon than that of Wilderness Park and the Rob Prairie, confirming our predictions. We are waiting for the soil samples to dry to start the pH and nutrient analysis. This study will help us determine the effects of urbanization on soil quality and what steps we will need to take to decrease impacts on urban soils.


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