Title of Oral/Poster Presentation

Niche differentiation of ammonia oxidizing bacteria and ammonia oxidizing archaea: seasonal dynamics, soil profile, ammonia oxidation kinetics and temperature sensitivity

Class

Article

Department

Plants, Soils, and Climate

Faculty Mentor

Jeanette Norton

Presentation Type

Oral Presentation

Abstract

Nitrification is a key process in the nitrogen cycle of agricultural soils. The first and rate-limiting step of nitrification is carried out by ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA). However, our understanding of the relative contribution of AOA and AOB to nitrification in different environmental conditions is limited. In this study, our goal is to determine whether AOA and AOB show niche differentiation through the growing season and soil profile, and in their nitrification kinetics and temperature response. The study was conducted in a agricultural field after four years of contrasting N treatment: control (no additional N), ammonium sulfate (AS, 100 & 200 kg N ha-1), and compost (200 kg N ha-1). The differential inhibitor, 1-octyne was used to distinguish AOA and AOB contributions to soil nitrification. AOB nitrification potential was higher and strongly stimulated one month after fertilization in AS treatment, while it was relative lower and stable in control and compost through the growing season. AOA nitrification potential showed no difference among N treatments and it slightly increased at the end of the growing season. Nitrification potential assays through the soil profile (0-90cm) indicated that AOB played a dominant role in surface soils (0-30cm), while AOA was more dominant in subsurface soil (30-90cm). The analysis of nitrification kinetics showed distinct roles for the AOB and the AOA communities. The optimum temperature was higher for AOA (39°C) than for AOB (31°C). Understanding the niche differentiation of AOB and AOA to N sources will inform our ability to manage N more efficiently for agriculture.

Start Date

4-9-2015 1:00 PM

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Apr 9th, 1:00 PM

Niche differentiation of ammonia oxidizing bacteria and ammonia oxidizing archaea: seasonal dynamics, soil profile, ammonia oxidation kinetics and temperature sensitivity

Nitrification is a key process in the nitrogen cycle of agricultural soils. The first and rate-limiting step of nitrification is carried out by ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA). However, our understanding of the relative contribution of AOA and AOB to nitrification in different environmental conditions is limited. In this study, our goal is to determine whether AOA and AOB show niche differentiation through the growing season and soil profile, and in their nitrification kinetics and temperature response. The study was conducted in a agricultural field after four years of contrasting N treatment: control (no additional N), ammonium sulfate (AS, 100 & 200 kg N ha-1), and compost (200 kg N ha-1). The differential inhibitor, 1-octyne was used to distinguish AOA and AOB contributions to soil nitrification. AOB nitrification potential was higher and strongly stimulated one month after fertilization in AS treatment, while it was relative lower and stable in control and compost through the growing season. AOA nitrification potential showed no difference among N treatments and it slightly increased at the end of the growing season. Nitrification potential assays through the soil profile (0-90cm) indicated that AOB played a dominant role in surface soils (0-30cm), while AOA was more dominant in subsurface soil (30-90cm). The analysis of nitrification kinetics showed distinct roles for the AOB and the AOA communities. The optimum temperature was higher for AOA (39°C) than for AOB (31°C). Understanding the niche differentiation of AOB and AOA to N sources will inform our ability to manage N more efficiently for agriculture.