HAL Id: hal-02742749
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Managing the biological function of N2O reduction for mitigating soil N2O emission
Catherine Hénault, Jean-Pierre Cohan, Cécile Le Gall, Marion Bardy, Xavier Galiègue, Romaric Philippon, Cécile Revellin
To cite this version:
Catherine Hénault, Jean-Pierre Cohan, Cécile Le Gall, Marion Bardy, Xavier Galiègue, et al.. Man-
aging the biological function of N2O reduction for mitigating soil N2O emission. Our Common Future
Under Climate Change, Jul 2015, Paris, France. 858 p., 2015, Our common future under climate
change. International scientific conference. Abstract book. �hal-02742749�
Ø Agriculture, through soil emissions, is an important anthropogenic source of the greenhouse gas N2O, that has a Global Warming Potential 300 times higher than CO2 on a molar basis (UNEP, 2013) .
Ø In soils, N2O is mainly produced through the microbial processes of denitrification and nitrification (Butterbach-Bahl et al., 2013)
Ø The last step of the denitrification process is currently the only known pathway for the terrestrial removal of N2O. N2O reduction is catalyzed by the N2O reductase enzyme encoded by the nosZ gene. Some soils are currently unable to reduce N2O : [SOIL]
PhN 2 ORed-
Ø We hypothesized that strategies to mitigate N2O emissions from agricultural soils could be based on the promotion of the N2O reduction.
Ø We are currently developing two different approaches for promoting the biological reduction of N2O in soils.
Managing the biological function of N2O reduction
for mitigating soil N2O emission
Key words : greenhouse gas N2O, soil, mitigation
Hénault C.(1), Cohan J.P.(2), Le Gall C.(3), Bardy M.(4), Galiègue X.(5), Philippon R.
(6), Revellin C.(7)
(1) INRA, UR SOLS 0272, Orléans, France
(2) ARVALIS, La Jaillère, La Chapelle Saint Sauveur, France
(3) CETIOM/TERRES INNOVIA, Thiverval Grignon, France
(4) INRA, US INFOSOL, Orléans, France
• Currently we have detected 11 strains amongst the Bradyrhizobium japonicum, lupinus and arachis, Ensifer meliloti, Rhizobium leguminosarum and elti species, having the nosZ gene being functional.
• During the greenhouse experiment, we measured a reduction rate of 0.10 µg N-N2O g-1 nodules h- 1 by Bradyrhizobium japonicum MSDJG49 for N2O being at the atmospheric concentration.
• We estimated that a soja crop inoculated with MSDJG49 can reduce 74 g N-N2O ha-1 on a 5 months period, which correspond to 70% of the N2O theorically emitted by the soil during the same period (Hénault et Revellin, 2011).
References
Butterbach-Bahl et al. 2013. Nitrous oxide emissions from soils: how well do we understand the processes and their controls? Phil. Trans. Roy. B Soc. 368: 20130122.
Hénault et al., 2005. Predicting "in situ" soil N2O emission using a NOE algorithm and soil database. Glob. Change Biol. 11:115-127
Hénault C., Revellin C. 2011. Inoculants of leguminous crops for mitigating soil emissions of the greenhouse gas nitrous oxide. Plant and Soil. 346:289-296.
Jolivet C., Boulonne L. & Ratié C., 2006, Manuel du Réseau de Mesures de la Qualité des Sols, édition 2006, Unité InfoSol, INRA Orléans, France, 190 p.
UNEP (2013) : A UNEP synthesis report. UNEP, Nairobi, Kenya.
With the financial support of
Mechanisms involved in the N2O budget in soil
Introduction in soil of strains able to reduce N2O by the use of the symbiotic relationship of crops-
microorganisms
[SOIL]PhN 2 ORed- + [Plant + Inoculant ]PhN 2 ORed+ [SOIL + Plant + Inoculant ] PhN 2 ORed+
Management of soil physico-chemical properties [SOIL(pHa, CECa, Ca,…) ]PhN2ORed- [SOIL(pHb,
CECb, Cb,…)]PhN2ORed+
• Use of the symbiotic relationship of leguminous crops - Rhizobiaceae to introduce strains of Rhizobia able to reduce N2O (Sameshima-Saito et al., 2006) .
Sampling and physico-chemical
characterisation of 90 soils from the RMQS, the French Soil quality Monitoring Network (Jolivet et al., 2006).
• Characterisation of these soils’ capacity to reduce N2O (protocol under iso
standardization).
• Database analysis, prediction of soil capacity to reduce N2O.
• Field application of results, with N2O fluxes measurements using the static chamber
method.
• The soil capacity to reduce N2O can be predicted by a PLS model based on soil pH, CEC and soil clay content. Soils with a low pH had appeared unable to reduce N2O.
• The field application is currently based on 2 field experiments performed during 2014 on acidic soils including control and limed plots.
• N2O emissions were lowered (by
approximately a factor 2) on limed plots compared to control ones due to an
activation of the N2O reduction.
• Detection of the nosZ gene into a collection of 147 strains of Rhizobiaceae and test of its functionality.
• Measures of N2O reduction rates at the greenhouse scale by soja plants inoculated with 3 different strains.
• Calculation of the potential of mitigation of an inoculated soja crop using (1) greenhouse results, (2) a database collected on a fertilised wheat, (3) the NOE algorithm (Hénault et al., 2005) .
Materials and Methods
Results
Discussion
Introduction
(5) Université d’Orléans, Laboratoire d’Economie, Orléans, France (6) AgroPithiviers, Coopérative agricole, Pithiviers, France
(7) INRA, UMR AgroEcologie, Dijon, France
Roots of a nodulated soja
Greenhouse experiment on soja
Detection of the nosZ gene by PCR
Ø A promotion of the N2O reduction function in soil allows mitigating soil N2O emissions.
Ø The promotion of the N2O reduction function in soils is possible both by biological (introduction of Rhizobia able to reduce N2O) and chemical (soft liming of acid soils) manners. It has been demonstrated at the greenhouse scale for the biological strategy and at the field scale for the chemical one.
Ø Introduction of Rhizobia is coupled to leguminous cropping. The most efficient strain currently detected is Bradyrhizobium japonicum MSDJG49, symbiote of soja. The promotion of N2O reduction by the Rhizobia strategy is without any transfer of pollution.
Ø Liming for promoting N2O reduction concerns soils with a pH lower than 6.4. The objective is to obtain a pH around 6.8 to 7.0 for a functioning of the N2O reduction with an increase of CO2 and NH3 emissions as low as possible.
Effect of strains on N2O budget during the greenhouse experiment
Estimation of the environmental benefit of the proposition
N2O emission by soil
by nodules inoculated into soybean
in a hypothetical system including active nodules
Sampling sites covering the France area
Kinetics of denitrification of soil C and soil L placed in anaerobic conditions with nitrate addition, without acetylene (……) and with acetylene ( )
Soil C, able to reduce N2O
Soil L, unable to reduce N2O
