Total Nitrogen, Organic Carbon and Soil Ph in a Long Term Continuous Winter Wheat (Triticum aestvum L.) Experiment

Abstract

Continuous use of organic and inorganic fertilizers 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 organic carbon (OC), 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, 25oC. Analysis for OC and TN were conducted using a LECO dry combustion CN 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. The use of commercial fertilizers lowered soil pH over time and did not change TN and OC. Manure application maintained 2% OM and adequate soil pH (>6.0).