Quantifying Analytical Error over the Years in Soil Test Data in a Long Term Continuous Winter Wheat (triticum aestvum l.) Experiment.

Inconsistency in soil analysis methodology over the years can be a source of error when comparing long term data. Changes in laboratory equipment and personnel can introduce small variations in analysis practices resulting in analytical error. The objective of this study is to quantify this error by reanalyzing stored samples collected in the last 24 years and compare it to the data gathered from the same samples throughout the years. The parameters being analyzed are Soil Organic Carbon (SOC), Total Nitrogen (TN), and soil pH. To determine these parameters, the same methodology is being applied as in previous years, however with time equipment has been replaced as have the people running the analysis. For SOC and TN a LECO dry combustion analyzer was used and pH was read on an electronic pH meter using a 1:1 soil to water solution. The samples utilized on this study were taken from a long term continuous winter wheat experiment, the Magruder Plots. The samples were air-dried at ambient temperature, ground to pass a 2mm sieve, and stored at room temperature of 25^oC.