Quantification Of Gross Nitrogen Transformation Rates Within A Conventional Potato Rotation Using Stable Isotopes

Abstract

This study used the isotope pool dilution method to estimate gross rates of mineralization, nitrification, NH4+ and NO3- consumption, and denitrification emissions over two growing seasons within a conventional barley-red clover-potato crop rotation on Prince Edward Island. Gross rates within the 2010 season were, in most cases, not significant across crop species or sampling date. In comparison, gross nitrification, NH4+ consumption, and NO3- consumption rates in 2011 were greatest within the potato crop following planting and hilling. However, rates were highly variable within both seasons. Error analysis indicated that variation in soil mineral nitrogen concentrations between duplicate cores was the greatest source of error. The use of the isotope pool dilution method to estimate gross nitrogen transformation rates using intact cores was not viable within this production system due to high and variable soil mineral nitrogen concentrations, particularly following fertilizer application.