Dr Patricia Garnier1, Dr. Mickael Hedde2, Dr David Makowski3, Dr Michel Bertrand3
1INRA, UMR Ecosys, Thiverval Grignon, France, 2INRA, Eco&Sol, Montpellier, France, 3INRA, UMR Agronomie, Thiverval Grignon, France
In most of soil organic matter models, the action of macroorganisms such as earthworms (EWs) is not represented. In order to build a model simulating the effect of EWs on the mineralization of soil organic matter (SOM), we used a statistical model based on a meta-analysis approach that allows taking into account the main experimental results of the selected literature. First, a database was built using the following steps: literature review, selection of references, data extraction, build a table of the input variables and finally choice of the response variable. Second, several statistical models (programmed in R-language) were tested with the experimental data set between the carbon mineralization response variable and the various explanatory variables selected. The results of the database show that there is an increase in carbon mineralization with the presence of earthworms and also that the effect of earthworms varies greatly between studies. To describe the effect of time, random-effect models are better than fixed-effect models and therefore this indicates that inter-study variability must be taken into account. The cubic model is better than the linear and quadratic models. Among the explanatory variables other than time, only the density makes it possible to improve the model. Thus an equation is proposed to calculate the effect of earthworms on soil carbon mineralization using a cubic model for time and linear for the density.
Dr Patricia Garnier is a senior researcher at INRA, UMR EcoSys, Grignon, France. She was awarded a Ph.D. in soil science in 1996, from the University of Nancy in France. She then worked as a post-doc at Cornell University, USA. She has authored or co-authored 63 articles in international peer-reviewed journals. Her main research activity concerns the modelling of soil processes like water transport, organic matter transformation, soil structure dynamic, organic contaminant movement… She has been in charge of several large research projects including international exchanges with China, Germany, etc…She is the leader of the national ANR project Soil µ3D (2015-2018) dealing with the modelling of organic matter on soil pores. She has also been leader of several other French national projects.