Proceedings of the 2020 Mississippi Water Resources Conference

Year: 2020 Authors: Stevens E., Yasarer L.M. W., Taylor J., Locke M., Moore M.

As a historical floodplain of the Mississippi River, MS Delta soils are anticipated to have high natural nutrient content. In addition, years of farming and fertilizer applications have altered natural nutrient compositions and potentially created a legacy storage of soil phosphorus on agricultural land. This study is a step in a series of analyses and experiments to characterize and quantify legacy soil phosphorus in a variety of common soil types found in either agriculture or forest habitats throughout the Mississippi Delta. Soil and sediment samples were taken from 73 locations comparing agriculture and forest environments within four different soil types: Dundee, Forestdale, Alligator, and Sharkey. Samples were taken in triplicate to total 219 samples, which were each homogenized in the laboratory. The field-moist samples were processed immediately, while the dried samples were air-dried, ground, and sieved to less than 2mm. Both field-moist and dried samples were extracted in aerobic environments. Extractions were performed on field-moist samples to extract water soluble phosphorus. Samples were analyzed for carbon, nitrogen and sulfur on an elemental analyzer. Mehlich-3 extractants were analyzed for phosphorus, potassium, calcium, magnesium, sulfur, sodium, iron, manganese, zinc, copper, boron, and aluminum using inductive coupled plasma (ICP) mass spectrometry. This initial analysis will compare soil phosphorus content in managed-agricultural vs. "natural" forest habitats, evaluate the spatial distribution of nutrient content throughout the Delta, and evaluate correlations amongst measured nutrient and mineral components. This work sets the stage for a deeper analysis of phosphorus availability in different soil types and development of predictive relationships to estimate phosphorus in soils throughout the Delta.