[Defended thesis] Myriam Allo: Agricultural land use, land use changes and agricultural practices: impacts on soil carbon stocks in tropical volcanic environment

Agricultural land use, land use changes and agricultural practices: impacts on soil carbon stocks in tropical volcanic environment. Spatial approach and simulation applied to Reunion Island

My name is Myriam Allo, and I've been working in La Réunion, where I've been hosted by 2 laboratories, CIRAD's AIDA and Ird's Eco&Sol, since October 2016. I am an Agricultural Engineer, graduated from Bordeaux Science Agro, with a specialization in Agricultural Land Management. During my agronomy studies, I did several internships with CIRAD on land-related issues. And after my end-of-study internship in La Réunion, I returned to the island for this thesis project.
In a context of climate change, the soil has a major role to play as it represents a carbon reservoir 2 to 3 times larger than the atmosphere. The 4p1000 initiative proposes to protect agricultural soils and increase soil carbon stocks in order to combat climate change. One of the 4 research pillars of this initiative is the estimation of soil organic carbon storage potential.
My subject aims to spatially assess the organic carbon stocks of Réunion's agricultural soils, as well as the impact of changes in land use on these soil carbon stocks. Data mining tools to identify carbon determinants, models to predict carbon stocks using infrared spectroscopy and a carbon balance calculator will be used to map carbon stocks and simulate the impact of changes in land use on the scale of the island.

• Starting date: October 2016
• University: MUSE Montpellier Université d'Excellence / Institut Agro
• PhD school: GAIA
• Scientific field: Agronomy, soil science, geomatics
• Thesis management: Emmanuel Torquebiau, Cirad
• Thesis supervisors: Pierre Todoroff, Cirad AIDA, Alain Albrecht, Ird Eco&Sol, Laurent Thuriès, Cirad Recyclage et Risques
• Funding: Cirad - Ademe
•  #DigitAg: Labeled PhD - Axes 5  et 6 - Challenge 1

Keywords: Carbon stock, land use change, agricultural soils, carbon balance, infrared spectroscopy, data mining, spatial analysis

Abstract: One solution to reduce greenhouse gases emissions is to improve carbon storage in soils. This mechanism is widely dependent of environmental factors and agricultural practices. Besides, knowledge of greenhouse gases balance of agricultural systems is a key element for climate-change driven environmental policy. However, required data to calculate these balances in French and tropical ultra-marine regions is still scarce. The aim of this thesis is to develop new knowledge at different spatial and temporal scales in order to evaluate the carbon storage functions in agricultural soils in Reunion Island (sugarcane, pasture and gardening). The project is based on a huge database; more than 42 000 soil chemical analyses have been done on agricultural soil samples from 1993 to the present. This database will be analyzed, completed by environmental data and agricultural practices to describe and map the evolution of soil organic carbon contents at different spatial and temporal scales in Reunion Island. Data mining will also be used to identify and quantify the influence of environmental factors and / or agricultural practices which determine the dynamics of soil organic carbon contents. These results will be translated in soil organic carbon stocks by complementary measurements of soil bulk density. An original and innovating methodology to evaluate soil carbon contents and stocks with infrared spectroscopy (near- and mid-IR) will be developed in order to minimize analysis costs. A participatory approach with stakeholders from agricultural and environmental sectors and the scientific community will be used to elaborate concerted and realistic scenarios shared by everyone. These scenarios will be evaluated under the angle of carbon stocks with the support of a cartographic carbon balance calculator developed within the framework of the project “C@RUN”. This approach should make easier the accession of institutional, professional and social stakeholders to the proposed scenarios, simulation results and facilitate the transfer of the mapping tool to potential users. The project relies on a close partnership between CIRAD and IRD, and associates one of the main agricultural trading partners of Reunion Island, the Tereos Indian Ocean agribusiness group.

Communications & Papers

Download the thesis manuscript

• Allo M., Todoroff P., Jameux M., Stern M., Rosies B., Ramos M., Quero S., Albrecht A.. 2018. Beyond infrared spectroscopy and spatial analysis : SOC stocks mapping in volcanic soils of Reunion island.. Rio de Janeiro : s.n., 1 p.. World Congress of Soil Science Soil Science: beyond food and fuel. 21, 2018-08-12/2018-08-17, Rio de Janeiro (Brésil). https://www.21wcss.org/anais/inc/abstract.php?id=1316
• Allo M., Todoroff P., Jameux M., Stern M., Ramos M., Quero S., Albrecht A.. 2017. Quick assessment of soil organic carbon stocks for scaling up issues, using infrared spectroscopy on volcanic soils. s.l., 1 poster. Climate Smart Agriculture 2017: « catalyser les innovations et les actions locales pour accélérer l’extension de CSA ». 4, 2017-11-28/2017-11-30, Johannesburg (Afrique du Sud)
• Allo M., Albrecht A., Legier P., Goge F., Jameux M., Thuriès L., Todoroff P.. 2017. Long-term diachronic series for soil carbon saturation evidence : A case study on volcanic soils of Reunion island under sugarcane crops.. In : Abstract Book Pedometrics 2017. Wageningen : Wageningen University and Research Centre, ISRIC, p. 19-19. Pedometrics, 2017-06-26/2017-07-01, Wageningen (Pays-Bas).

http://www.pedometrics2017.org/s/Abstract-Book-Pedometrics-2017.pdf

Contact:  pierre.todoroff [AT] cirad.fr