IDENTIFYING SEASONAL ENVIRONMENTAL TRIGGER EVENTS AND THEIR INFLUENCE ON SOIL MICROBIAL RESPIRATION AND GREENHOUSE GAS EMISSIONS IN A NOVA SCOTIA AGRICULTURAL SOIL

Abstract

N2O is released from agricultural soils as a result of nitrification and denitrification. These microbial processes are affected by environmental conditions. This study developed a method of predicting trigger environmental events that would induce a response in soil respiration and examined that response under natural field conditions, considering the influence of N-Viro® alkaline biosolid amendment. Additionally, the utility of 15N site preference and the Picarro® Cavity Ring-Down Spectrometer to distinguish the source of N2O (nitrification or denitrification) from surface flux samples obtained on 15N labelled-NH4NO3 sites was investigated. It was confirmed that trigger events influence the magnitude of soil respiration and N2O emissions from agricultural soils with rewetting events dominating the magnitude of N2O flux. Indicators of nitrification increased with increasing biosolid amendment rate and NO3 accumulation was greater at deeper soil depths. The CRDS provided evidence that nitrification was the dominant source of N2O, based on site preference.