Soil Organic Carbon (SOC), Total Nitrogen (TN), and Soil pH, in a Long Term Continuous Winter Wheat (Triticum Aestvum L.) Experiment.

Continuous use of organic and inorganic fertilizers will impact soil properties such as organic matter and soil pH, in addition to nutrient levels. In order to document these changes, stored samples from the last 24 years of the Magruder Plots were analyzed for soil organic carbon (SOC), total nitrogen (TN) and soil pH. This long term trial has received the same six-unreplicated-treatments since 1947.  These consist of a combination of cattle manure, inorganic N, P, K, and lime applied when pH dropped below 5.5. Each year, a composite soil sample was taken from the surface 0-15cm in each plot, air-dried at ambient temperature, ground to pass a 2mm sieve, and stored at room temperature, 25^oC. Analysis for SOC and TN were determined using a LECO dry combustion analyzer, and pH was measured using an electronic pH meter with a 1:1 soil to deionized water solution. Statistical analysis was performed using SAS.

Expected results: The use of commercial fertilizers lowered soil pH over time. Where manure was applied, SOC and TN increased. Due to the buffer capacity provided by the addition of organic matter, pH in these plots were maintained significantly above those plots where inorganic fertilizers were applied.