Soils

Methodology

I. Materials

• Curly stakes/landscaping stakes
• Tape measure
• 1 m string
• Paper bags – for collecting soil samples initially
• Ziploc bags – for storing soil samples in freezer (make sure they are well labelled)
  • Are there biodegradable options available?
• Soil corerGNSS device
• Nitrile gloves
• Ethanol (80%)
• Paper towels
• Bucket
• Scrub brush for cleaning between samples
• Cooler and freezer packs

II. Sampling Preparation

Fig. 1 - Construction plans for the Eco-Commons. Locations marked in yellow are "scraped" areas, while locations in gray are "original".

One of the primary Piedmont regions in the Eco-Commons (Labelled as ____ in Fig. 1) was selected for analysis this semester. To accurately account for differences in soil composition as a a result of construction practices, the sampling points were selected from two different areas within the region, with areas retaining the original soil labelled as “original” (OG; areas marked in grey on Fig. 1) and those where the top 10” of soil were scraped away labelled as “scraped” (SC; areas marked yellow on Fig. 1). Within each area of either OG or US soils, ten sample sites were randomly selected by approximating photographed construction patterns in Google Earth (Fig. 2 and Fig. 3), with sites only being selected if they were approximately 10 meters away from another. If a site was within 10 meters of another site, it was excluded and a new randomly selected point was selected.

IV. Sample Drying

Samples were air dried on 18 March 2022 in Room 2-66 at the Gilbert Hillhouse Boggs Building. Counter tops were first cleaned with 70% ethanol. Container lids were subsequently cleaned using the cleaning procedure below:

Rinse with 70% ethanol

Rinse MiliQ water

Scrub with Alconox soap

Rinse with MiliQ water

Rinse with 70% ethanol

Following one hour of air drying, tape was used to visually separate the container lid into two sides and paper towels were added to the container lids to hold the soil on top of the container. Soil samples were then added to the paper towels and roots and stones were removed as recommended by Cong et al. 2015. After air drying for three days, soil samples were prepared for geochemical analyses.

V. Geochemical Analysis

The geochemical analysis of the soil cores included two phases. In the first phase, soil samples were packaged and delivered to the University of Georgia Cooperative Extension for an extensive geochemical analysis by the UGA Soil, Plant, and Water Laboratory.  Each bagged sample was brought to the county UGA extension office and submitted, along with the corresponding submission forms that include address, plant grown in the soil, sample numbers, and county code. For shipping efficiency, the bags were assorted into soil sample shipping boxes at the office. The corresponding soil analysis included a routine test (testing for soil pH, lime, extractable Phosphorus, Potassium, Calcium, Magnesium, Manganese, and Zinc) and a more advanced test (testing for Sodium, Iron, Copper, Chromium, Molybdenum, Nickel, Cadmium, Lead, cation exchange capacity, and percent base saturation).  

VI. Analysis

Samples were air dried in a controlled lab environment for 96 hours and then delivered to the UGA Extension East Point office. Once received, results of nutrient density were converted from units of pounds per acre to milligrams per kilogram. According to the University of Florida IFAS Extension, we can convert from pounds per acre to ppm by multiplying the pounds per acre value by a factor of 0.5. This conversion is based on two assumptions: that the root depth / sampling depth is 6 inches, and that the nutrients are in elemental form. Both these assumptions are satisfied based on our sampling procedure and the UGA extension soil test results. Additionally, according to Kansas State University, 1 ppm of a nutrient/contaminant in soil is equal to 1 mg/kg of the contaminant. This data was then analyzed using [what statistical test??] .