Soil nitrate data for 120 point locations within limestone cedar glades at Stones River National Battlefield near Murfreesboro, Tennessee

This dataset contains data collected within limestone cedar glades at Stones River National Battlefield (STRI) near Murfreesboro, Tennessee. This dataset contains measurements of soil nitrate (parts per million) at certain quadrat locations (points) within 12 selected cedar glades. These measurements were obtained according to the following protocol: (1) for each quadrat location (point), one soil sample was obtained under sterile conditions, using a trowel wiped with methanol and rinsed with distilled water, and was placed into an autoclaved jar with a tight-fitting lid and placed on ice, (2) soil samples were transported to lab facilities on ice and immediately refrigerated, (3) soil samples were transferred to clean aluminum trays and dried at 35 degrees Celcius for 48 hours to produce air-dry soil, (4) air-dry soils were then passed through a number 10 sieve to remove rocks and root fragments, (5) soil slurries were prepared by adding 10 grams of sieved, air dry soil to 25 milliliters distilled water and one powder pillow of Hach nitrate ionic strength adjustor (ISA) (Hach Company, Loveland, CO, USA) into 125-milliliter plastic bottles, (6) soil slurry bottles were agitated on a reciprocating shaker for 20 minutes. Soil nitrate levels were measured using a nitrate-sensitive electrode (Hach Platinum Series combination nitrate electrode 51920, Hach Company, Loveland, CO, USA) connected to a Hach SensIon 1-millivolt meter (Hach Company, Loveland, CO, USA). Measurements were taken by immersing the nitrate electrode into each soil slurry and measuring readings in millivolts. Three millivolt readings were taken per soil slurry, and the electrode was thoroughly washed with deionized water and blotted dry between each slurry immersion. For each soil slurry, the mean was calculated of the three readings in millivolts. Soil slurry readings (means of three measurements) in millivolts were transformed into nitrate estimation using a two-stage calibration procedure. A calibration curve was established immediately prior to taking soil slurry readings, and another calibration curve was established immediately afterward. Both calibration procedures were performed at the same temperature as soil slurry measurements. A mean calibration curve was created using the mean of the pre- and post- sample calibration curves and the mean calibration curve was used to transform slurry millivolt readings into soil slurry nitrate estimates in parts per million. Estimates of soil nitrate (parts per million) were calculated by multiplying soil slurry nitrate estimates derived from the mean calibration curve by 2.5, according to the instruction manual for the Hach Platinum Series combination nitrate electrode 51920. Detailed descriptions of experimental design, field data collection procedures, laboratory procedures, and data analysis are presented in Cartwright (2014).References:Cartwright, J. (2014). Soil ecology of a rock outcrop ecosystem: abiotic stresses, soil respiration, and microbial community profiles in limestone cedar glades. Ph.D. dissertation, Tennessee State University.Cofer, M., Walck, J., and Hidayati, S. (2008). Species richness and exotic species invasion in Middle Tennessee cedar glades in relation to abiotic and biotic factors. The Journal of the Torrey Botanical Society, 135(4), 540–553.

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  "geospatial"
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