Project title: Characterisation
of the kinetics of N2 and N2O emissions and N2O
reduction in urine patches.
Supervisors: Prof Tim Clough, Lincoln University, New Zealand, Dr. Gary Lanigan
(Teagasc) and Dr Karl Richards (Teagasc, Ireland).
Background:
Denitrification of urinary nitrogen deposited to soil during grazing is the single largest
source of nitrous oxide (N2O) in grazing livestock systems. Denitrification is a stepwise
microbial process in which soil nitrate (NO3-) is progressively reduced to predominantly
N2O and nitrogen gas (N2). Under complete denitrification N2O is reduced to
environmentally benign N2, but N2O can be emitted from soils before it is converted
(incomplete denitrification). The reduction from N2O to N2 is the only known sink of N2O
in pastoral systems, and is catalysed by the microbial enzyme nitrous oxide reductase
(N2OR) which is encoded by the nosZ gene. The overall hypothesis of the research
proposed here is that these factors can be manipulated to accelerate N2O reduction to
N2 in urine patches, thereby reducing N2O emissions from grazing livestock systems.
In order to quantify the kinetics of the N cascade following urine deposition, a 15N
tracer approach will be utilised. This will allow us to elucidate the fate of applied urine
N, alter the factors influencing the partitioning of that N between various loss pathways
and quantify the fluxes associated with each of these pathways. A range of soils from
the various member countries with varying denitrification potentials and varying
management histories will be used.
This project brings together world-leading expertise across a wide range of disciplines
to disentangle the causal relationships between soil physic-chemical traits, soil
biochemistry and N2/N2O emissions in urine patches. This will significantly strengthen
our ability to identify novel manipulations and/or evaluate known manipulations that
can be used on farms to accelerate N2OR activity in urine patches. In addition, causal
relationships elucidated in association with international partners (Prof. Lars Bakken,
UMB, Norway, Dr. Ronnie Laughlin, AFBI, Northern Ireland and Dr. Sergio Morales,
Otago University, NZ) in other aspects of the wider project will enable paddock- scale
research to be more readily extrapolated to a wider range of soils, climates and
managements.
Specific Objectives include:
 To establish the key drivers of denitrification and co-denitrification
processes associated with urine patch deposition on grassland soils.
 To identify the key biochemical pathways governing the rate of codenitrification and/or denitrification.
For informal discussions about the project and your suitability contact Prof. Tim
Clough
Tim.Clough@lincoln.ac.nz
and/or
Dr
Gary
Lanigan
Gary.Lanigan@teagasc.ie.
Requirements: Applicants should have a primary degree (II.1 or Ist) and/or a
M.Sc. in an appropriate discipline (Chemistry, Biochemistry). A knowledge of
stable isotope science and/or soil science would be advantageous.
Funding: The position is funded by a Teagasc Walsh Fellowship; value €22,000
per annum, to cover postgraduate stipend and tuition fees.
Starting date: The project will start in February 2015. The funding is for a
three year Ph.D. project, to be completed by end of February 2018.
Location: The project student will receive initial training based mainly at both
locations depending on the experimental programme. Student will also be
required to travel to other partners in Otago, Northern Ireland and Norway.
Application
procedure:
Apply
using
online
http://www.teagasc.ie/research/postgrad/pgf_index.asp
Closing date for applications: 31st January 2015
facility
at: