Title: FairviewSnowmeltStudy_NMineralization_Summer2012_CalculationsAndFigures Author: Lafe Conner Affiliation: Brigham Young University, Department of Biology Address: 401 WIDB, Brigham Young University, Provo, Utah 84602 Phone: 801-422-2175 Email: connerlg@gmail.com Sponsors: Date Created: 20130415 (April 15, 2013) Date Last Modified: 20130415 (April 15, 2013) Abstract: This file contains the calculations and figures for nitrogen mineralization from a snowmelt experiment in Fairview Canyon, Utah. We melted the snow in 12 treatment plots using dust from the Clearlake area near Kanosh, Utah. The dust caused advanced snowmelt and water loss in the treatment plots. We compared the effects of dust-caused early snowmelt in 12 paired treatment and control plots. We also added dust to 12 dust-control plots. This dust was added immediately following snowmelt and was intended to be a control for the effects of dust fertilization. To measure net nitrogen mineralization we took two soil cores at the same time. We brought one core back to the lab for analysis and placed the second core back in its original location inside a clear plastic tube. The tubes are 5 cm in diameter (outside diameter) and 15.3 cm in length. These tubes were left in the field for 28 days and then brought back to the lab for analysis. All samples were analyzed the day after they were collected from the field. They were stored in coolers during transport and kept in fridge overnight. Methods: Net N mineralization was calculated from the raw data file (FairviewSnowmeltStudy_NitrogenMineralization_Summer2012_RAW.csv) by summing of NH4 and NO3 concentrations in the soil (ppm) at times 28 days apart. The first sample is called the “initial” and the second core is called the “incubated”. We subtracted the sum of N in the initial core from the sum of N in the incubated core and divided this value by the number of days of the incubation. To calculate net nitrification we subtracted the initial nitrate concentration from the incubated nitrate concentration and divided this value by the number of days of the incubation. To create the figures we used the pivot table tool in Excel 2010. We collected the average, standard deviation, and count of replicates for each time period in each treatment (control, dust, or dust control) in each cover type (aspen or meadow) and at each elevation (lower or upper). Purpose: The purpose of these data is to calculate net nitrogen mineralization from initial and incubated soil samples. The final data values derived in this data set are concentrations of NH4 and NO3 in the soil. Column Values and Details: Elevation – Values are “upper” or “lower” and designates which of the study sites the samples were taken from. Upper elevation sites are approximately 9500 feet and lower elevation sites are approximately 8700 feet. Cover – “meadow” or “aspen” SiteNumber – Values 1 through 12. Each site is number so that it is easy to keep track of where the data are coming from. Sites 1, 3, and 5 are in the lower meadow; sites 2, 4, and 6 are in the lower aspen; sites 7, 9, and 11 are in the upper meadow; and sites 8, 10, and 12 are in the upper aspen. Treatment – “Dust,” “Control,”, or “Dust Control” refers to the dust treatment. CollectionDate – The date soil cores were collected from the field. ExtractionDate – The date soils were extracted in the lab. IncubationCollectionDate – The date that the incubated cores were collected. IncubationExtractionDate - The date that the incubated cores were extracted. NH4ConcentrationSoilPpmInitial – This is the concentration of NH4 in the soil in ppm for the initial soil core. NO3ConcentrationSoilPpmInitial – This is the concentration of NH4 in the soil in ppm for the initial core. NH4ConcentrationSoilPpmIncubated – This is the concentration of NH4 in the soil in ppm for the incubated soil core. NO3ConcentrationSoilPpmIncubated – This is the concentration of NH4 in the soil in ppm for the incubated core. NetMineralization – is = NH4ConcentrationSoilPpmIncubated + NO3ConcentrationSoilPpmIncubated) – (NH4ConcentrationSoilPpmInitial + NO3ConcentrationSoilPpmInitial). NetNitrification – is = NO3ConcentrationSoilPpmIncubated - NO3ConcentrationSoilPpmInitial. DaysOfIncubation – the number of days between the collection of the initial core and the incubated core. DailyNetMineralization – is = NetMineralization / DaysOfIncubation DailyNetNitrification – is = NetNitrification / DaysOfIncubation Notes and comments about the data: These data were run at two different times by two different lab technicians. Samples 201 through 316 were run in July 2012 by MacKenzie Mayo and samples 317 through 418 were run in February 2013 by Megan Taylor. During the first attempt, the absorbance values were high so we diluted the samples by loading 50uL of sample and 150 uL of K2SO4 into the 96 well plate. This gives a 3rd dilution factor of 4 (total volume 200 uL / aliquot volume of 50 uL). We also had poor standard regression lines from this run, because our standards were very high (from 1 to 20 ppm). Therefore, we replaced the standard regression slope and intercept with an average value from the later trials. The soil weights for samples 386 to 418 were lost when our lab computer crashed so we entered an average soil weight based on the overall average of proportion of soil multiplied by 15 g of wet soil. In the last collection of soils there were no samples taken from the plots at lower meadow site 6. Comment on data quality: These data have several problems (described above), so it is not recommended that they be shared widely or used by anyone who does not comprehend these limitations. Use Restrictions: There are no legal restrictions to the use of these data.