Abstract:
Soil shear strength measurements were collected from two isolated freshwater marshes (Joyce Wildlife Management Area, an anchored marsh; Salvador Wildlife Management Area, a floating marsh) over 10 years after nitrogen (N) and phosphorous (P) additions were annually applied to the surface in spring. Porewater data was also measured at both sites.
Suggested Citation:
Turner, R. Eugene. 2019. Soil strength in two freshwater marshes after increased nutrient availability: Field nutrient addition experiments from 2009-04-15 to 2018-04-26. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-8vtv-yh64
Data Parameters and Units:
File Salvador_WMA_Soil_Strength_sub1.xlsx, worksheet "Sampling Key": Date: Date samples were collected in the sampling area (MM/DD/YY); Sampling Area: General marsh location; LAT (dec degrees): Latitude of sampling location; LONG (dec degrees): Longitude of sampling location; Site Conditions at time of measurements: Indicates type of measurements collected on the given date and/or nutrient condition of site
Worksheet "Porewater": Porewater data organized by the date the data was collected. Treatment: User-defined description of the treatment condition; Site: User-defined description of the sampling plot; Ammonia (uM/L): Ammonia concentration at each treatment plot; Nitrate/Nitrite (uM/L): Nitrate/Nitrite concentration at each treatment plot; Silicate (uM/L): Silicate concentration at each treatment plot; Phosphate (uM/L): Phosphate concentration at each treatment plot; DIN (uM/L): DIN concentration at each treatment plot.
Worksheet "1-June-2009": Soil Strength data collected within the sampling area before nutrient additions. Note that the Site numbers listed here are at pre-survey locations and not the same as the boardwalk site numbers assigned later for post-nutrient addition data. Soil strength was measured using a shear vane (kPa,kilo-newtons) at eight depths (10,20,40,60,80,100,120,140) that represent cm depth. Worksheets: 3-May-2011, 4-May-2012, 15-May-2013, 15-March-2014, 24-March-2015 Soil strength data are reported for up to six replicates, organized by nutrient treatment plot. Soil strength was measured using a shear vane (kPa,kilo-newtons) at ten depths (10,20,30,40,50,60,120,70,80,90,100) that represent cm depth.
File Joyce_WMA_Soil_Strength_sub1.xlsx, worksheet "Sampling Key": Date: Date samples were collected in the sampling area (MM/DD/YYYY); Sampling Area: General marsh location; LAT (dec degrees): Latitude of sampling location; LONG (dec degrees): Longitude of sampling location; Description of Sampling: Indicates type of measurements collected on the given date and/or nutrient condition of site.
Worksheet "Porewater": Porewater data organized by the date the data was collected. Treatment: User-defined description of the treatment condition; Site: User-defined description of the sampling plot; Ammonia (uM/L): Ammonia concentration at each treatment plot; Nitrate/Nitrite (uM/L): Nitrate/Nitrite concentration at each treatment plot; Silicate (uM/L): Silicate concentration at each treatment plot; Phosphate (uM/L): Phosphate concentration at each treatment plot; DIN (uM/L): DIN concentration at each treatment plot.
Worksheet "15-April-2009": Soil Strength data collected within the sampling area before nutrient additions. Note that the Site numbers listed here are at pre-survey locations and not the same as the boardwalk site numbers assigned later for post-nutrient addition data. Soil strength was measured using a shear vane (kPa,kilo-newtons) at six depths (10,20,40,60,80,100) that represent cm depth. Worksheets: 12-Mar-2014, 12-Feb-2015, 27-Mar-2016, 29-March-2017, 7-March-2018 Soil strength data are reported for up to six replicates, organized by nutrient treatment site. Soil strength was measured using a shear vane (kPa,kilo-newtons) at ten depths (10,20,30,40,50,60,120,70,80,90,100) that represent cm depth.
Methods:
The experiments at the Joyce and Salvador WMAs were done along boardwalks marked with 1 x 1 m square plots and separated from each other by 1 m or more. Triplicate control plots were spaced along a boardwalk and others were 3 m outward from the boardwalk at a right angle. The Joyce WMA boardwalk was established April 2009, and the initial doses were made in June 2009. Subsequent doses were made in April 2010 and each year in the spring from 2013 to 2018. The dosing at Salvador WMA began in July 2009 lasted until March 2015. Each year there were three different levels of surficial additions of slow-release Osmocote (0.45, 1.36 and 2.26 kg N ha-1, and 0.14, 0.43 and 0.71 P ha-1, respectively), and single doses of superphosphate (SP; 0.52 kg P ha-1), and calcium nitrate (CaN; 0.25 kg N ha-1). Thus, there were 3 replicate plots each of a Low, Medium and High N and P addition, 3 plots of a P addition, and 3 plots of N additions. The timing of the dosage each spring varied depending on the weather. The doses used in these experiments ranged from 400 to 1000 kg N ha annually. The experimental plots at the end of the experiment were 6 and 10 years old for the Salvador WMA and Joyce WMA sites, respectively. Porewater samples were taken from the 10 cm soil depth after the shear vane measurements and before fertilization and kept in an ice chest until being frozen within 5 hr. The determination of inorganic ammonium, nitrate, phosphate and silicate followed EPA guidelines. Nutrient concentrations (µM) were determined on unfiltered water samples and analyzed within two weeks using EPA methodology (353.2, 350.1, and 365.2). Ammonium concentrations were determined using the Lachat Instrument's QuikChem method 31-107-06-1-B.
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