Effect of soil pH on nitrous oxide emissions from agricultural soils

Project

Automatisiertes Bodeninkubationssystem für eine kontinuierliche Erfassung von Gasflüssen am Thünen-Institut, Braunschweig (c) Thünen-Institut/AK (Patrick Wordell-Dietrich)
Automated soil mesocosm incubation system for continuous monitoring of gaseous fluxes at Thuenen Institute, Braunschweig (© Thünen-Institut/AK (Patrick Wordell-Dietrich))

Mitigating Agricultural Greenhouse Gas Emissions by improved pH management of soils (MAGGE-pH)

A climate smart pH regulation of agricultural soils could mitigate nitrous oxide emissions. Potentials and trade-offs will be examined  in MAGGE-pH.

Background and Objective

Nitrous oxide emissions from agricultural soils are a major greenhouse gas source within the sector agriculture. Soil microbial processes are responsible for nitrous oxide production and consumption.

Reactive nitrogen and organic carbon from fertilisation, crop residues remaining after harvest and humus are important precursors for microbial derived nitrous oxide production. The efficient use of these nutrient sources in the scope of good agricultural practice can mitigate nitrous oxide emissions. But the related mitigation potential is limited because fertilisation and incorporation of organic carbon sources (crop residues and amendments) are required to maintain optimal crop production and preserve soil humus contents. Management options that support the consumption of N2O in soils would be an efficient possibility to further increase mitigation potentials achieved by good agricultural practise.

The project MAGGE-pH examines the effect of soil pH on the relationship between nitrous oxide production and consumption assuming that an increase of pH will support the transformation of the potent greenhouse gas nitrous oxide to climate-neutral atmospheric nitrogen in soil. Thus nitrous oxide emissions could be mitigated by pH regulation. In MAGGE pH, combined laboratory studies, field experiments and model simulations will approximate the mitigation potential in North and Central Europe and New Zealand.

Approach

The Thuenen- institute participates with two work packages. One package will analyse the effects of soil pH on N2O production and consumption pathways and the sensitivity of these enzyme mediated reactions on soil environmental conditions by mesocosm and lysimeter experiments. In particular we are interested of pH effects on

  • nitrous oxide emissions,
  • the contribution of microbial processes on nitrous oxide production (nitrification, denitrification, nitrifier denitrification, fungal denitrification, heterotrophic bacterial denitrification, co- denitrification),
  • the ratio between nitrous oxide production and consumption,
  • mineralisation,
  • carbon dioxide losses due to mineralisation and liming,

The other package will enable process models and empirical approaches to consider pH effects that have been observed in lab and field experiments. These modelling tools will be applied at various spatial scales. We are interested in longterm effects of soil pH on greenhouse gas emissions, nitrate leaching and nitrogen use efficiency and related sensitivities on natural conditions. We will quantify mitigation potentials that would be achievable by a climate smart pH regulation on national scale. Moreover possible formulations of incentives or regulations to effectively mitigate nitrous oxide emissions in agricultural practise will be tested with regard to emerging costs and benefits.

Data and Methods

To examine pH effects on N cycling processes in detail we will conduct various lab experiments using mesocosms and lysimeters with and without vegetation. Automated gas measurements will be combined with stable isotope measurements (13C, 15N, 18O) to determine the transformation of N2O to N2. Because we are interested in long term pH effects soils from longterm experiments with various pH treatments will be used.

Process based models trained on lab and field data will be used to simulate longterm effects of pH management on greenhouse gas fluxes, crop yield and N leaching. Starting with field experiments conducted by project partners within MAGGE pH we will analyse these long term effects for various weather conditions and soil properties.

Established stochastic models used to predict nitrous oxide emissions at national or global scale will be extended by a pH response and used to quantify national nitrous oxide emissions from agricultural soils. Scenarios of good agricultural practice will be compared with scenarios assuming a climate smart pH regulation to approximate mitigation potentials by pH regulation.
The agro-economic mode RAUMIS will be extended to consider effects and costs of pH regulation. The integrated approach combining RAUMIS and a stochastic N2O model will then be used to examine the impact of national incentives and regulations on income, production, greenhouse gas emissions and land use.  

Our Research Questions

  1. Can it be shown by field experiments that soil pH mitigates nitrous oxide emissions?
  2. How does pH influence microbial driven nitrogen and carbon cycling processes in agricultural soils?
  3. What is the mitigation potential of pH regulation on national scale?
  4. How incentives or regulations should be designed to realize the maximal N2O mitigation potential with in the same time minimized costs and effects on productivity, land use and production?

Links and Downloads

MAGGE-pH at ERA-GAS
MAGGE-pH on ResearchGate

Thünen-Contact


Involved Thünen-Partners


Involved external Thünen-Partners

  • Aahrus University
    (Tjele, Dänemark)
  • Norwegian University of Life Sciences
    (Ås, Norwegen)
  • University of Helsinki [FI]
    (Helsinki, Finnland)
  • INRA
    (Clermont Ferrand, Frankreich)
  • TEAGASC
    (Johnstown, Irland)
  • NATIONAL UNIVERSITY OF IRELAND GALWAY
    (Galway, Irland)
  • University of Otago
    (Otago, Neuseeland)
  • Swedish University of Agricultural Science - SLU
    (Uppsala, Schweden)
  • Natural Environment Research Council (NERC)
    (Edinburgh, Großbritannien (Vereinigtes Königreich))

Funding Body

  • Federal Office for Agriculture and Food (BLE)
    (national, öffentlich)

Duration

11.2017 - 10.2020

More Information

Projekt type:
Project funding number: 2817ERA07C
Funding program: EU - JPI on Agriculture, Food Security and Climate Change (JPI FACCE)
Project status: ongoing